Monday, January 31, 2011

Jan 31, 2011: Major Snow, Sleet And Ice Storm

Today brought generally partly cloudy skies to the area with chilly temperatures observed, however precipitation has already started moving into the Mid Atlantic and will move into the area later tonight from what will be a storm full of extremes, ranging from blizzard conditions in Chicago and nearly 20 inches of snow to a major ice storm from Pennsylvania into parts of the area.


Tomorrow's Forecast: Moderate Snow/Sleet

Tomorrow will bring the first part of the storm. Precipitation will move in from the west late tonight, with widespread light to moderate snow affecting the area by the early morning. The heaviest precipitation from this wave, however, will stay to the north of the area, and with 850 mb temperatures rising above freezing, the snow will change over to sleet from south to north, first in the eastern parts of the area in the mid morning, the immediate NYC area in the late morning, and the northern and northwestern parts of the area in the early afternoon. Sleet will fall through the mid afternoon hours, when precipitation should start to move out of the area.

By the time that precipitation from this round of the storm ends, at least 2 to 4 inches of snow and sleet are expected for New York City and further south/east, 3 to 5 inches in the immediate NYC area, and 4 to 7 inches for the northern parts of the area, including parts of interior southern Connecticut and Orange County, NY. An update on this round of the storm may be posted tomorrow in the early afternoon.


Tuesday Night - Wednesday Night: Major Ice Storm

As previously mentioned, the 850 mb temperatures will rise above the zero degree mark for most of the area by tomorrow afternoon. Instead of surface temperatures warming up too, however, we will see a cold air damming scenario, where the cold air will remain trapped in the surface, so while 850 mb temperatures will be above freezing, surface temperatures will remain in the 20s. This is a set up for a major ice storm.

During the early to mid overnight hours on Tuesday night, generally dry conditions are expected, though a few light sleet or freezing rain showers are possible at times. Between 1 and 4 AM, precipitation will move in from west to east. While the precipitation type may start out as sleet in some places and potentially snow in the northernmost parts of the area, by the early morning hours, a widespread moderate freezing rain is expected for the area, leading to a dangerous morning rush hour.

As surface temperatures will warm up, places south and east of NYC will change over to rain by the morning, with NYC and its immediate north/west suburbs changing over to rain by 10 AM, which will be heavy at times. Places further inland, however, will have a more prolonged period of ice, and may fail to change over to rain at all. The precipitation will continue to fall moderately to heavily through the mid-late afternoon hours, when the main storm should end, with the potential of some light snow in the evening to the early overnight hours. With temperatures quickly dropping into the 10s and 20s, black ice is expected for the immediate NYC area and further south/east.

When this round of the storm ends, at least 0.2 to 0.5 inch of freezing rain is possible in the immediate NYC area, with the potential of over 0.5 inch of freezing rain further inland. This will be a very dangerous storm, and has the potential of bringing significant ice accumulations. Stay tuned for more information on this storm tomorrow.

Sunday, January 30, 2011

Jan 30, 2011: Snow, Ice And Rain Coming Up

Today finally brought a return to dry conditions after the area has seen snow for 5 consecutive days. Temperatures tonight will drop into the single digits inland with highs in the 20s inland, however this dry period will not last for long before yet another storm moves in, with more snow, ice and rain.


Tuesday - Wednesday Night: Snow, Ice And Rain


Looking at the latest models, there are no significant changes from the forecast yesterday, and I have decided to issue an Ice Storm Watch for the interior parts of the area and a Snow Watch elsewhere. For today's forecast, I mainly used the 12z NAM and 12z/18z GFS runs. The 18z NAM came in much colder, with as much as a foot of snow for northern New Jersey and over 6 inches of snow in NYC, however as of now it has little support, and I am waiting to see tomorrow's runs to determine whether this is a new cold trend or just an off run.


Tuesday Storm: Snow To Sleet

The storm will start on Tuesday morning with an overrunning event. Light snow will overspread the area during the early morning and will become moderate by the mid to late morning hours from east to west. By the late afternoon, the 850 mb zero degree celsius line will begin to move north through the area, however cold air will remain in the surface, preventing a changeover to rain and instead resulting in a changeover to sleet from south to north between 2 and 6 PM.

By then, at least 2 to 4 inches of snow are expected in Long Island, 3 to 5 inches for southern Connecticut and the immediate NYC area, and 4 to as much as 7 inches of snow for the western parts of the area. There is some uncertainty with exactly how much snow falls, and these amounts may have to be slightly lowered or raised. Stay tuned for more information on Tuesday's event.


Tuesday night into Wednesday: Bigger Storm, Significant Ice Possible

On Tuesday night, a break in the precipitation is expected with occasional light sleet as a bigger storm develops to the west of the area. While the low will track towards Illinois, it will be blocked from moving further north with a high pressure to the north of the storm, which will also help supply the storm with a lot of cold air, and will be forced to move east through Pennsylvania and into New Jersey.

Precipitation will move in from west to east on Wednesday morning. 850 mb temperatures will be above 0c in most of the area, though surface temperatures will still be below freezing, resulting in freezing rain developing for the area. As temperatures warm up from south to norh, the coast will quickly change over to rain, with New York City also changing over to rain by the mid morning hours. Places north and west of NYC, however, will deal with a more prolonged ice event, with NE NJ and southern Connecticut changing over to rain by the late morning with the potential for 1/4 inch of freezing rain.

The interior parts of the area may never change over to rain at all, though there is some uncertainty as some models bring in enough warmth to change the interior parts of the area to rain in the afternoon while other models keep enough cold air to prevent a changeover to rain. This potential will be watched, however if precipitation type fails to change over to rain, as much as 0.5 to even 0.7 inch of freezing rain may be possible, which may result in significant damage.

In the immediate NYC area, heavy rain will fall by the mid and late afternoon hours, with at least 1 inch of rain possible. This may lead to significant flooding, especially with snow cover over 15-20 inches in some spots. By the time that the storm ends overnight, temperatures will quickly drop into the 10s and 20s with the entire area changing over to light snow. In places where heavy rain falls, black ice could form by Thursday morning.


This will be a dangerous storm for the East Coast, with impacts ranging from as much as 12-24 inches of snow for the interior Northeast, a major ice storm for parts of the northern Mid Atlantic, and flooding in places that see heavy rain. Stay tuned for more information on this storm over the next few days.


Longer Range: Tomorrow's update will have a little more on the longer range, including the potential for colder temperatures in the late week and another rain or snow storm for Saturday.

Jan 30, 2011 Noon: Alerts Issued

5:00 PM:

It is possible that I may not be able to post a more detailed discussion on this storm tonight, though for now, I issued a Snow Watch for the entire area with an Ice Storm Watch for the interior parts of the area. For the latest alerts, please refer to the "Weather Alerts" page. The "5-Day Forecast" page was also updated for the central and western parts of the area.

The latest expectation is for snow to develop on Tuesday, with 2 to 4 inches for the eastern parts of the area, 3 to 5 inches in the immediate NYC area, and 4 to 7 inches for the interior parts of the area. The snow will change to sleet by the late afternoon, with a break in the precipitation overnight. Freezing rain will develop by the morning, changing over to rain in the immediate NYC area by the afternoon with significant icing possible inland.

This is still subject to some slight changes. Stay tuned for more information on this storm.

Saturday, January 29, 2011

Jan 29, 2011: Wednesday Storm Discussion

Today was a mostly cloudy day for the area, with another clipper producing light snow for the area with accumulations less than 1/2 inch. Conditions will dry up starting tomorrow, with tomorrow being the first day since Monday the 24th that the area has not seen snow. Another storm is expected to affect the area by the middle of the week, however this time, rain and ice are a bigger concern than snow.


Sunday And Monday: Cold Again

Tomorrow will be slightly warmer than yesterday, with high temperatures expected to be in the mid 30s inland and in the mid to upper 30s for the rest of the area. Tomorrow night, however, is expected to be very cold, with low temperatures back into the single digits inland and the 10s for the rest of the area including NYC. Monday will bring colder high temperatures, expected to be in the mid 20s inland and in the mid to upper 20s for the rest of the area.


Mid Week Storm: Some Snow Tuesday, Then Mix/Rain

While yesterday, the model guidance suggested a storm that may bring mostly snow with some mixing with sleet for the area, today's models have trended warmer and further north, most notably the GFS, and now bring some snow to ice, then heavy rain for the area. Below, I will discuss in more details what factors I used in today's forecast and how it may change.

It appears that the storm will come in two parts. The first part will be an overrunning event on Tuesday, where an area of moderate snow is expected somewhere near or north of the area. For this part of the storm, I used the NAM, which has been the most consistent in showing this event clearly, while the GFS only has been trending a little wetter with some light precipitation. It appears that the area will see snow to start on Tuesday with light to potentially moderate snow accumulations possible, with perhaps a few inches at most, followed by a changeover to mixed precipitation by the evening or overnight as 850 mb temperatures warm above 0c but surface temperatures remain below freezing.

For the second part of the storm, I used a solution close to the 12z/18z GFS. This will be the main storm and will be during the day on Wednesday, though the models have been trending wetter, warmer and further north. The GGEM is currently the southernmost solution with snow/mix for the area, though it appears to be too far south and with that model still being inconsistent, I did not use the GGEM for my forecast tonight. It appears that we may see a mix changing over to rain, potentially heavy at times.

Jan 29, 2011 Morning: More Snow Today

As was mentioned over the last two days, a clipper is currently affecting central Pennsylvania with moderate snow, and is moving east to ESE towards the area. While it is expected to weaken as it crosses Pennsylvania, some light to locally moderate snow can be expected across the area this afternoon, with the steadiest snow currently headed towards central New Jersey.

Precipitation amounts will be light with this clipper, though up to 1 inch of snow is possible across parts of the area, especially west or just south of NYC. If Central Park sees an inch of snow today, it will break the record for the snowiest month on record, which is not certain but it is a possibility depending on exactly how much snow falls. The snow should end by the early overnight hours.


The next update will be posted tonight, focusing on the mid week storm.

Friday, January 28, 2011

Jan 28, 2011: Storm Potential On Wednesday

Notes: The 5-Day Forecast was updated for the immediate NYC area only tonight. It will be updated for the rest of the area later tonight or tomorrow morning.

A new poll has been opened for Wednesday's storm. In addition, below are the results for the poll for yesterday's storm on its effect in the NYC area:

Total Votes: 58 votes

2 votes - Storm south of NYC, no snow
3 votes - Storm clips NYC with light snow
5 votes - Moderate snowstorm
31 votes - Major snowstorm
10 votes - Snow changing over to rain
7 votes - Mostly rain storm


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Today was a mostly cloudy to cloudy day across the area as a weak clipper brought light snow mainly to the south of the area but with some light snow also affecting the NYC area, with a general dusting of snow and light snow still ongoing. Another clipper is on the way for tomorrow focusing further north that may bring a quick 1/2 to 1 inch for the area, with colder temperatures behind the clipper, however there is yet another storm threat for the medium range, and while it may not bring plain snow to the area, it still has the potential to be a big weather maker across the region.


Weekend Outlook:

Tomorrow will bring yet another weak clipper that will move through the area, though this time the clipper will be further north than that of today. Even though most of the snowfall from this clipper will fall to the west of the area as it weakens while moving east, it will still bring a widespread light snow to the area. A general dusting of snow is expected, though some places could see up to 1/2 inch, potentially up to 1 inch if there is more snow than expected.

Temperatures on Saturday will be in the lower to mid 30s across the area, with Sunday a little warmer.


Mid Week Storm: Significant Snow/Ice?

There continues to be uncertainty with the storm in the middle of the week, however the latest models are suggesting that another storm will affect the area during this time frame, with more snow possible once again. The storm track, however, is still uncertain, and puts the range for this storm from a major snowstorm to a mostly rain event.

It appears that we will see a primary low pressure on Tuesday night move through Tennessee into the Ohio Valley, with a transfer taking place to a low further east. The question is where this transfer takes place, with some models showing this further south with a major snowstorm for the area, others showing it near the area with snow to ice, and others further north with some snow to rain. There is still uncertainty with which solution verifies, though at this time I am leaning more towards the snow to ice to some rain solution. This is still in the longer range though, and is subject to change. Stay tuned for more information on this storm.

Thursday, January 27, 2011

Jan 27, 2011: Cold And Snow Not Over Yet

The region has been stuck under a consistently cold and snowy pattern since December, with today's major snowstorm shattering records for January snowfall, and as I will mention in more details below, there is the potential for Central Park to break its record for the snowiest month of all time, which was February 2010. The cold and snowy pattern is nowhere near its end, however, as there is yet another storm potential for next week with the longer range models indicating that the current pattern persists through the 15 day range. In addition, a long range outlook for February that will be posted within the next week or so will also discuss the potential for this winter to reach or even break the record for the snowiest winter on record, with 20 more inches needed to reach that record.


Friday And Saturday: Mainly Cloudy, Occasional Light Snow

Tomorrow will be a mostly cloudy to cloudy day across the area with high temperatures in the lower to mid 30s north and west of NYC, and in the mid 30s for NYC and further east. A weak clipper will bring widespread light snow to the region, mostly to the south of the area where light accumulations up to about 1/2 inch may be possible, though some snow showers are still expected for the area tomorrow afternoon into the evening hours with a general dusting of snow possible.

Another clipper will move through on Saturday afternoon and evening, however this clipper has the potential to be slightly stronger than that of tomorrow. While it will not be a significant snow producer, it has the potential of dropping an inch of snow across parts of the area. If New York City records at least an inch of snow over the next two days, this month will officially break the record for the snowiest month in recorded history in Central Park. At this time, NYC is expected to see less than an inch of snow, however this potential will be monitored.


Longer Range: Another Storm Potential Next Week

The latest models continue to suggest that a storm is possible during the middle of next week, but its track and how it affects the area is still uncertain. There are two main groups of solutions at this time, with the GFS and ECMWF models showing a further south and weaker storm, with the 12z GFS and 18z DGEX showing yet another major snowstorm for parts of the area. The GGEM and UKMET are further west, with mostly rain for the area. There is uncertainty on which scenario verifies at this time, though it does appear that there may be a round of snow on Tuesday, separate from this storm threat for Wednesday into Thursday. Stay tuned for more information on this storm.

Snowiest January On Record

According to the National Weather Service, as of 1 AM, New York City broke its record for the snowiest January on record, with 32.3 inches in Central Park compared to the previous record of 27.4 inches in 1925. Similar records were broken across parts of the area. As this was released as the storm was still ongoing, however, New York City saw more snow afterwards, and there is the possibility that if the weak clippers that will affect the area tomorrow and Saturday bring at least an inch or more of snow, New York City might break its record for the snowiest month on record, which was set in February of last year with 36.9 inches. Central Park is still far from reaching the snowiest winter on record, which was 1995-96 with 75.6 inches of snow, however if we also see a snowy pattern for February, which is a reasonable possibility, it could be possible that we may approach this record, as at least 20 more inches are needed to reach this record.

As new totals continued to come in after this morning into the NWS list of snow reports, it appears that the highest snow totals came in from the immediate NYC area, with a reported 19 inches of snow in Central Park, 19.5 inches in Rahway, NJ, and there is also a 20 inch report in Richmond County.

Looking more into what happened last night, if the snow bands had remained with 1-2 inch per hour rates as expected, then my forecast amounts of 7 to 14 inches for the immediate NYC area would have verified, however the bands that set up over New York City were much stronger than anticipated, even nearing 40 dbz, with snowfall rates as high as 3 to even 4 inches per hour! Similar conditions were observed further southwest where the storm also ended up overperforming across the Interstate 95 corridor including Washington DC and Philadelphia.


A storm summary will be posted on this event sometime over the next few days, and tonight's update will focus on the longer range, discussing the light snow events for Friday and Saturday that will bring a total of a dusting to 2 inches of snow across the area, and a potentially bigger storm on Wednesday, where there is uncertainty with solutions ranging from a storm well to our west with rain and warmth to a coastal storm with yet another major snowstorm.

Wednesday, January 26, 2011

Jan 26-27, 2011 Storm Updates


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Below, storm updates will be posted on the storm that will affect the area through the morning of Thursday, January 27.

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7:15 AM: The storm has ended across the area over the last several hours, however snow rates that exceeded the expectations resulted in higher snow totals than expected, with this storm bringing a widespread 12+ inches to the area, shattering snow records for January as well as pushing snow totals across the area to levels almost as high as those of last winter only by late Jaunary, with even more cold and snow left in the winter.

Last night, it was mentioned that places just north/west, near, and east of NYC continued to see occasional mixing with sleet keeping the highest totals further west, and that the highest totals would end up north and west of NYC. While places north and west of NYC saw higher totals than those in NYC, with reports of 17-18" in Union County, NJ and 17" in West Norwalk, CT, as the snow fell at heavier rates than expected, a more accurate call would have been to keep the forecast snow in NYC the same and raise totals north and west of NYC, instead of keeping the same snow forecast north and west of NYC and slightly lowering the snow totals in NYC.

This was overall a difficult storm to forecast, with the models constantly moving back and forth from a storm bringing a major rainstorm to the area to a storm out to sea, and this ended up as yet another major snowstorm in a record breaking winter that is still far from over. A storm summary on this storm will be posted sometime over the next several days.

The next update will be posted tonight, with information about upcoming light snow events for Friday and Saturday and a potentially bigger storm around Tuesday.



10:00 PM: Most of the area is currently seeing moderate to heavy precipitation, however there continues to be mixing with sleet in the immediate NYC area. It appears that snow totals need to be slightly lowered for NYC and the immediate N/W suburbs, with a total of 5 to 8 inches overnight. Places further north and west of NYC appear to end up with the highest amounts, with a storm total between 10 and 14 inches possible.

This was the last update for tonight. Another update will be posted tomorrow morning after the storm ends.




9:35 PM: Over the last hour, New York City saw mainly sleet, with some rain mixed in for eastern Long Island, and snow west and north of NYC. New York City is now changing over to plain snow, and the changeover to snow will continue to move east through Long Island. Meanwhile, heavy snow will continue falling over NE NJ and NYC, with snow rates between 1 and 2 inches per hour. Windy conditions will lead to near zero visibility at times.

Northwestern New Jersey is currently seeing moderate to locally heavy snow, which will continue over the next several hours.


8:30 PM: **WARNING:** The thunderstorm that moved through New York City over the last hour weakened earlier, however over the last 10 minutes it has quickly intensified in Westchester and Rockland counties, with a 45-50 dbz band moving north through these areas. This band will continue to move north to affect the rest of Rockland county, extreme eastern Orange county, Putnam county, and extreme western CT, including Danbury. This band is capable of producing very heavy snow and sleet, gusty winds, and thunder. Take caution if you are in this storm's path.


7:00 PM: A heavy thunderstorm previously mentioned is currently moving into New York City, producing heavy sleet mixed with snow, thunder, and gusty winds. This thunderstorm, however, is only the start of what's to come this evening. Heavy snow and sleet in New Jersey is moving northeast, and will start to affect the area between the next 1-2 hours.

While some mixing with sleet is expected early on, the precipitation type will then change over to snow from west to east, with the result being a widespread heavy snow across the area in the early overnight hours. Snow rates between 1 and 2 inches per hour are possible, and some thunder is also possible early on. By the time that the storm ends between 3-6 AM, an additional 6 to 10 inches of snow are expected for the immediate NYC area, with similar but slightly lighter amounts in eastern Long Island.


6:40 PM: **WARNING**: A heavy thunderstorm is currently located off the coast of New Jersey quickly moving north, and will affect New York City, Nassau county in LI, extreme SW Connecticut and Westchester county over the next 1/2 to 1 hour. The storm could also potentially affect extreme NE NJ and SE Rockland County if it extends further west. Very heavy snow and sleet can be expected with this band, as well as lightning and thunder. There have also been reports of hail with this cell. Strong wind gusts are also expected. Take caution if you are in the path of this storm.


4:25 PM: Earlier this morning, the area saw a round of heavy snow with accumulations generally between 1.5 and 4.5 inches so far across the area. This was the result of the storm moving in earlier than expected and with heavier precipitation than expected.

Currently, most of the area is seeing isolated light sleet showers, though a band of heavy snow and sleet is currently near Bergen and Rockland counties moving NE, and is capable of producing a quick coating of snow. As the storm continues to intensify, heavy snow, sleet and rain along with thunder are affecting places such as Maryland, and the heavy precipitation will continue to move ENE to affect the area from this evening into the overnight hours. Until then, light snow/sleet will continue to fall, mixing with light rain further east, changing over to snow from west to east this evening.

At the worst of the storm, heavy snow will focus over the immediate NYC area with snow rates between 1 and 2 inches per hour, and windy conditions will lead to low visibilities. In addition to what fell today, another 6 to 8 inches of snow are expected in the immediate NYC area into southern Connecticut tonight, potentially as much as 10 inches of snow, leading to a storm total of 7 to 14 inches of snow. Lighter snow will fall in the western parts of the area, with an additional 3 to 6 inches of snow expected tonight.

Tuesday, January 25, 2011

Jan 25, 2011: More Snow Is On The Way


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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This morning, the area experienced a surprise 1 to 3 inch snowfall event. Some light snow was expected, however accumulations this high were unexpected. Temperatures went on to peak in the 30s across the area, which are the warmest temperatures the area has seen in days, yet are still below the average highs. Even more snow is on the way, however, as a storm currently affecting the Southeast will move northeast to bring a significant snowstorm for the area.


Wednesday - Thursday Storm: Heavy Snow Expected

The models have converged on a solution slightly east of yesterday's forecast throughout the day today. There is still some slight uncertainty with exactly how much precipitation falls, with the 00z NAM model showing the lightest amounts, however at least 6 or more inches of snow are expected to fall near the immediate NYC area.

Storm Forecast: The low pressure that will affect the area is currently near the southern United States, with its pressure between 1008-1010 mb. This low pressure will move northeast, and will be located near eastern North Carolina by tomorrow morning. The low pressure will continue to move northeast from there but will quickly intensify, with at least a 986 mb low pressure expected south of Nova Scotia by late tomorrow morning.

The radar appearance of the storm is expected to remain relatively disorganized until it reaches the Mid Atlantic tomorrow afternoon, which is when it will begin to organize and intensity, with heavy precipitation moving northeast overnight from central/northern Virginia into New Jersey and southern New England.


Forecast For The NYC Area: A wintry mix of light snow, sleet and rain will begin falling tomorrow afternoon across the area, however the precipitation will remain light through the evening hours. As the storm continues to organize, heavy precipitation will approach the area from the southwest, and with dropping temperatures as cold air works its way into the storm, the area will change over to plain snow from west to east.

The worst of the storm will take place on Wednesday night into early Thursday morning. Heavy snow is expected to affect the central parts of the area with moderate snow further west, with snow rates between 1 and 2 inches per hour possible with the heavier snow bands. By the time that the storm is over on Thursday morning, I am expecting at least 4 to 8 inches of snow in NW NJ and Orange County, NY, and 6 to 10 inches for the rest of the area except eastern Long Island, which could also see 4 to 8 inches of snow.

Note that there is still some uncertainty with the exact precipitation amounts, and it is possible that the heavy snow area could be shifted slightly west, slightly east, or it is a possibility that there could be less snow than expected. Stay tuned for more updates on this storm tomorrow.


With the next full update, more information will be posted about a potential light snow event around Saturday, and another possible arctic air blast around the first day of February.

Monday, January 24, 2011

Jan 24, 2011 Brief Update


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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10 PM Edit: The 5-Day Forecast page was updated for the central and western parts of the area tonight. The next full update will be posted tomorrow night along with a full update for the 5-Day Forecast.

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Due to technical difficulties, no full update will be posted tonight. A brief update will be posted tomorrow in the evening, with the next full update tomorrow night.


Update On Wednesday-Thursday Storm: Significant Snowstorm Potential

There was a lot of uncertainty with the storm until yesterday, when most of the models were all over the place, however today the models began converging on a solution. The latest expectation is for precipitation to begin falling on Wednesday in the late morning, starting out briefly with widespread light snow, changing over to rain closer to the coast and a wintry mix further inland with temperatures generally in the 30s.

On Wednesday night, the worst part of the storm is expected. As colder air comes in along with heavier precipitation, most of the area will change over to snow, with the potential for heavy snow in the central and western parts of the area. There is still uncertainty on how much snow falls, however there is the potential for 6 or more inches of snow to fall between Wednesday night and Thursday morning in NYC and further west.. Stay tuned for more information on this storm tomorrow.

Sunday, January 23, 2011

Jan 23, 2011 Morning: Forecast Changes



***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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12:00 PM: Last night's and this morning's model runs brought a big change from yesterday's forecast, with the inland track no longer favored. While yesterday, I went with a track that would hug the coast, bringing snow to rain for the area and snow inland, the western models have shifted east, with the western solutions being a coastal hugger on the GGEM and the eastern solutions being an out to sea storm on the GFS model. Even though the track is further east on these models, there is still the problem of a lack of strong cold air, meaning that even if the storm is in a favorable position for a significant snowstorm, it may result in a wintry mix in the area. The storm is also much slower with the latest models, only starting on Wednesday afternoon.

There is still a lot of uncertainty with this storm, and my forecast remains a low confidence one, though I may make an afternoon update with major changes to the 5-day forecast, including slightly lowering forecast temperatures, slightly lowering probability of precipitation, and delaying the storm's timing to Wednesday afternoon through early Thursday morning. Stay tuned for more information on this storm.

Saturday, January 22, 2011

Jan 22, 2011: Update On Wednesday's Storm



***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Note:

Below are the results for the poll that was active for how yesterday's storm (Friday, Jan 21) would affect the area:

0 votes - Weak storm, snow south of NYC
8 votes - Storm clips NYC with light snow
16 votes - Big storm, heavy snow in NYC
4 votes - Big storm too close to coast, rain/snow mix

A poll remains open for Wednesday's storm effect on the area. Please vote your thoughts in the poll, which will close on Tuesday morning.

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As an arctic air mass moved into the region, today brought much colder temperatures for the area, with high temperatures only in the lower to mid 20s across the area. Temperatures this morning were very cold, getting as low as -5 degrees in Sussex, NJ!

Tonight's temperatures have already dropped below the expectation, already below zero in interior areas, and as a result I have lowered forecast low temperatures for tonight, now expected to be between -8 and -2 degres inland, lower to upper 0s for the north/west suburbs of NYC and southern Connecticut, and lower to potentially mid 10s in NYC.

Tomorrow will be slightly warmer than today, bringing high temperatures in the lower to mid 20s across the area. Tomorrow night will bring temperatures similar to, if not even colder than those of tonight, and as a result Monday will be a very cold day, with high temperatures only in the mid to upper 10s across the area and a few lower 20s possible near/south of NYC. Afterwards, however, the cold will weaken as a storm approaches the area, bringing rain and snow to the area.


Wednesday's Storm: Big Storm, But Not A Big Snowstorm?

In my update yesterday, I mentioned how some models were further west with the storm and others were east, and while I went with the western solutions, I did not rule out the possibility that solutions further east verify. Today's models continue to be variable, however there continues to be evidence suggesting that this storm may end up hugging the coast or tracking inland, bringing more of a wintry mix and/or rain event for the area rather than yet another big snowstorm.


Model Analysis: Today's models have been more variable, however we have seen some interesting trends, especially with the GFS model. The GFS had difficulties handling this storm this morning, showing completely different solutions than most models with snow staying even to the south of the area, and while its 12z run has made corrections, showing a Miller A type of storm, or a low coming up the East Coast, it still has more trending to go through. Its 18z run did show a slight westward trend, though it remains one of the easternmost solutions for this storm, and I am expecting the GFS to continue trending west at this time, though how far west it trends is uncertain.

The GGEM model remains consistent with the idea of some snow/mix changing over to rain, heavy at times, for the area, though it hasn't been very consistent with the timing and location of the storm, with its 12z run being much slower, further southwest, and stronger. While its 12z run may be too slow and perhaps too warm, which are some biases that the GGEM has in some cases, such a westward solution cannot be completely ruled out yet. The ECMWF model continues to take the storm close to the coast, apparently with mixing issues for the area, and the NAM model, which started to come into range today, went with a west track closer to that of the GGEM, however this is still the NAM's longer range when its accuracy is not as good as when compared to its medium/short range, and it is expected to change at least several more times before becoming more consistent.

While this storm does have the potential to be a significant snowstorm for the area, the pattern is not as favorable as it could have been, especially with a high pressure to the north of the storm moving east quickly and a lack of blocking. We are also missing strong cold air with this storm, something that has been in place with almost every significant winter storm this winter. The majority of the model and model trends today suggest that the storm may track near the coast or inland, however there is still a spread with how each model handles the storm. At this time, I am going for a solution east of the GGEM/NAM but west of the GFS, though this is still subject to change, and it is possible that the models may trend west towards the GGEM/NAM with a big rainstorm, or the GGEM/NAM could trend east with a snowstorm for the area.


Current Thoughts For NYC Area: There does appear to be cold air when the storm starts, meaning that the storm may start with at least some wintry precipitation, however some models bring more snow to start, while others such as the 12z GGEM have only a little front end snow/mix followed by a heavy rain event. Based on the solution I previously described I am leaning towards, the storm will start on Tuesday night with precipitation possibly in the form of snow or a wintry mix, with temperatures warming up. By Wednesday, I am thinking at this time that places near and east of NYC may change over to rain, with a wintry mix further inland, potentially rain if the warmer case scenario verifies. Regardless of precipitation type, it appears that precipitation has the potential to be heavy, and I mentioned potentially heavy precipitation in the 5-Day Forecast.

The scenario described above is only my thinking at this time, and the exact precipitation type is still a relatively low confidence forecast. It is possible that may see a further west scenario, with a little snow/mix to start followed by heavy rain, or we may see a further east scenario with mostly snow for the area. Regardless of the uncertainty, this has the potential to be a major storm in the East Coast, and needs to be watched closely for impacts ranging from heavy snowfall to significant flooding. Stay tuned for more information on this storm.

Friday, January 21, 2011

Jan 21, 2011: Significant Storm Potential Wednesday


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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The snowstorm that affected the area early today ended by the late morning, with partly to mostly cloudy skies and scattered snow showers observed for the rest of the day. Snow totals were generally between 2 and 6 inches across the area, however the storm did bring heavier snow totals as it moved northeast into the rest of southern New England and Maine.

Behind this storm, what may be the coldest air mass of the winter is moving into the region, and is expected to bring low temperatures in the single digits for Sunday night across most of the area with sub-zero lows inland. While the cold pattern will not end afterwards, as indications are showing that it may last into February, the main focus at this time is on a potentially significant or major storm for Wednesday that will affect the region.


Saturday - Monday: Extreme Cold

Tonight will be very cold for the area, with low temperatures expected to be in the lower to mid 0s inland, mid 0s to lower 10s for the north/west suburbs of NYC and S CT, with mid 10s in NYC. Tomorrow will be a partly sunny day but with temperatures much colder than those of today, in the upper 10s inland and in the upper 10s to to mid 20s for the rest of the area.

The cold will relax a little on Saturday night as a weak low pressure to the north of the area brings mostly cloudy skies and scattered flurries, with low temperatures still cold but not as cold as those of tonight. On Sunday, high temperatures will be in the lower to mid 20s across the area with clearing skies, though the second and strongest part of the cold spell will move in.

Sunday night is expected to be very cold, with low temperatures near or below zero degrees for most of the area away from NYC and Long Island. Low temperatures may even get as low as nearly -10 degrees for the westernmost parts of the area, and an Extreme Cold Alert may be issued there. Even New York City may see low temperatures in the single digits.Monday will then be a very cold day, with high temperatures in the mid to upper 10s across the area, with a few isolated areas near NYC potentially reaching the 20 degree mark.

Monday night will still be very cold, especially for the eastern and central parts of the area, where low temperatures near zero degrees in southern Connecticut are possible. While there is plenty of more cold air to come, the attention for now turns to a major storm for Wednesday.


Tuesday - Thursday: Significant Storm Expected, Uncertainty With Precip Type

As I mentioned this morning, there is now agreement with the forecast models that a significant storm is expected for Tuesday into Thursday. The main question at this time, however, is how the storm affects the area, as it appears that this storm may track close enough to the area to bring a wintry mix during Wednesday.


Model Analysis: Other than most models showing an intense storm, the smaller details including the track, intensity and timing are different which can be expected in this time range. The GGEM model has one of the westernmost solutions at this time, with some front end snow changing to heavy rain and temperatures well into the 40s, The ECMWF was in between with what appears to be a wintry mix for the area, and the GFS has been more variable, showing a snow to rain storm with its 06z run and a major snowstorm with its 12z and 18z runs.

The pattern in this case is not as favorable for a major snowstorm focusing on the area as some other storms were, including a lack of blocking and a high pressure that exits quickly, and at this time a blend of the more reliable model runs seems to take the storm right up the coast, with a major snowstorm further inland into places such as Pennsylvania, and a wintry mix for places further east including the Interstate 95 corridor. A snow storm is still a possibility for the area though, as it is possible that a faster solution like that of the GFS verifies and brings a moderate or heavy snowstorm for the area. For my forecast tonight, I used the 12z ECMWF and the 06z GFS, though this is still subject to change over the next few days. It is possible that we may see the eastern, faster and weaker solutions of the GFS verify, and it is also possible that we may see a storm further west, closer to the GGEM.


Current Thoughts For NYC Area: At this time, it is certain that the storm will affect the region as well as the NYC area. I went a little conservative and put a 90% chance of precipitation at this time, though if there are no major changes I will likely raise it to 100% with tomorrow's update. As we will see a very cold air mass exiting ahead of the storm, with cold air in place to start, the storm is expected to start out as snow across the area, though what happens afterwards becomes more uncertain and depends on what the storm does.

There are timing differences concerning when the storm starts and ends, with solutions ranging from the snow entering during the day on Tuesday to the storm only starting on Wednesday afternoon. At this time, I went with the in between solutions, showing snow starting on Tuesday night, though with uncertainty concerning the timing, this is subject to change. During the day on Wednesday, when the storm may make its closest approach to the area, if the western solutions verify, it will track close enough to NYC to change the precipitation type to rain with a wintry mix further west, but if the storm is east enough, it may keep most of the area with plain snow. It is also possible that we see a weaker storm in which the area sees more of a moderate snow event. In the 5-Day Forecast, I leaned towards the western solutions, showing snow changing over to a mix or rain for NYC and a snow/mix further west, though this is still subject to change.

It is important to note that we are still 5 days away from the storm, and we may see solutions ranging from a big storm bringing some snow to rain, to a storm bringing a major snowstorm to the area, to a weaker storm with lighter snow for the area. While I am leaning more towards the western solutions at this time, the other scenarios are just as possible and cannot be ruled out. Stay tuned for more information on this storm over the next several days.

Jan 21, 2011 Morning Update



***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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7:10 AM: Through the late overnight to early morning hours, we saw moderate to locally heavy snow affecting the western and central parts of the area. The storm has ended for the western parts of the area, and will end for most of the immediate NYC area from 7 to 8 AM as the back end of the storm comes through.

For the eastern parts of the area, however, the worst of the storm is only starting, with the moderate to heavy snow currently in SW CT and moving ENE. The snow near the back end of the storm is intensifying as expected, and will bring widespread moderate to heavy snow across southern into central Connecticut, where 4 to locally 7 inches of snow are expected. Long Island is currently seeing snow mixing with sleet and rain in some places. The snow will end there later this morning.

Another update may be posted later this morning, otherwise the next update will be posted later tonight, focusing on a potentially intense storm that will affect the area on Wednesday, bringing the potential for a mix of rain and snow.

Thursday, January 20, 2011

Jan 20, 2011: Snow Tonight, Then Extreme Cold


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Today brought mostly cloudy skies to the area as clouds moved in due to yet another storm approaching the area, which will produce a widespread moderate snowfall. While temperatures today were chilly across the area, they are about to get much colder as what may end up as the coldest air mass of this winter and the coldest temperatures since January 2009 affect the area this weekend, with parts of, if not most of the area failing to reach the 20 degree mark for highs.


Tonight And Tomorrow's Outlook: Moderate Snowfall

We are currently seeing widspread snow in Pennsylvania, associated with a low pressure currently near West Virginia. This low pressure will continue to move east northeast, and later tonight will be located off the coast, not too far SE of New York City. As the storm quickly moves northeast, moving over far eastern Long Island, it will intensify faster, and will likely be near 990 mb once it reaches Cape Cod in the early afternoon tomorrow. The storm will continue to rapidly intensify and organize itself, bringing heavy snow and wind to downeast Maine, where slightly over a foot of snow is expected. The storm will then exit the region, pulling down extremely cold air with it.

For the area, expect to see light snow spreading from west to east between 10 PM and 1 AM. The snow will be light at first, however as the low pressure moves near the area, moderate to locally heavy snow will fall between 4 and 7 AM for places near NYC and further west, and between 6 to 9 AM for the eastern parts of the area. The snow will then end from west to east in the morning for the western parts of the area, and in the early afternoon for the eastern parts of the area.

Expected Snowfall: When the storm ends, at least 4 to 6 inches of snow are expected in the western and central parts of the area, with the highest totals in the immediate NYC area being in the northern suburbs. The highest amounts across the area will be in southern Connecticut, where as much as locally 7-8 inches of snow are expected.

Looking across the rest of the region, the moderate to heavy snow axis will extend from the area into southern New England, where 5 to 10 inches of snow are expected, and as the storm continues to intensify, heavy snow will fall in downeast Maine, where the highest snow totals out of the northeastern US will be, with slightly over a foot of snow expected.



Weekend Outlook: Coldest Since January 2009

Over the last week, I occasionally hinted at the possibility that high temperatures may fail to reach the 20 degree mark in parts of the area this weekend and widespread single digit readings for lows in the colder case scenario, and this now appears to be reality with what will be the coldest weekend since January 2009, when highs across most of the area were in the 10s and low temperatures were in the single digits for most of the area.

The cold will come in two waves. The first wave will come on Friday night into Saturday, with low temperatures on Friday night expected to be in the lower to mid 0s inland, mid 0s to lower 10s for the north/west suburbs of NYC and southern Connecticut, upper 0s to lower 10s for Long Island, and lower to mid 10s for NYC. High temperatures on Saturday will be very cold, in the upper 10s inland, upper 10s to mid 20s for the immediate NYC area, and lower to mid 20s for the eastern parts of the area.

On Saturday Night, the cold will briefly weaken as a weak low pressure near the Great Lakes brings mostly cloudy skies and warmer overnight lows, in the mid to upper 0s inland and in the lower to upper 10s for the rest of the area. Sunday will be slightly warmer than Saturday, with clearing skies and high temperatures in the upper 10s to lower 20s inland and in the lower to mid 20s for the rest of the area, however this weak low pressure in the Great Lakes will reinforce the cold air, with even colder temperatures.

Sunday night may very well end up as the coldest night of the winter. Mostly clear skies are expected, and low temperatures are expected to quickly drop across the area. There is some slight uncertainty with exactly how cold it gets, but low temperatures below zero are expected in the western parts of the area, and have the potential of getting as low as -5 to -10 degrees. In the immediate NYC area, even New York City may reach the 10 degrees mark, if not drop slightly below 10 degrees, with the suburbs further north/west as well as southern Connecticut seeing low temperatures in the lower negative single digits to the mid 0s. Monday will be a very cold day, with high temperatures in the mid to upper 10s across the area with a few lower 20s possible.


Middle Of Next Week: More Significant Storm Potential?

For the middle of next week, the latest models are suggesting a more significant storm threat, however there is a wide spread of solutions at this time ranging from a storm tracking to the west of the area with a wintry mix, to a storm off the coast bringing a snowstorm for the area, to a storm staying out to sea. There is still uncertainty at this time, and I will discuss this storm in more information once details become clearer, however the storm is likely to affect the area with at least some precipitation at this time. Stay tuned for more information on this storm.

Wednesday, January 19, 2011

Jan 19, 2011 Brief Update


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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No full update was posted today, and while the alerts page was not updated tonight, expect light snow alerts and snow warnings to be posted tomorrow in the late afternoon. The next full update will be posted tomorrow night.


Brief Update On Friday's Storm:

Yesterday, there was still a spread with the model guidance, some of them suggesting a light snow event and others suggesting a 6-10 inch snowfall. Today's models have backed away from the bigger snowstorm scenario, and the general consensus with the models is for a widespread light to moderate snow event, with precipitation amounts for the area at least between 0.15 and 0.35 inch. This would normally suggest 1.5 to 3.5 inches of snow, however as there appears to be the potential for higher liquid to snow ratios, at least 2 to 5 inches of snow are expected at this time across the area, with the highest amounts towards the eastern parts of the area. This range is not final yet, and some slight adjustments could be made to it with tomorrow's update. The snow will start to fall tomorrow night, with the steadiest snow in the early morning hours, ending by the late morning or early afternoon hours.

Stay tuned for the final forecast on this storm tomorrow along with a map, an update on the arctic air blast for this weekend, and another storm that may affect the area between January 25-26.

Tuesday, January 18, 2011

Jan 18, 2011 Brief Update


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Today's update is a brief one, with a short discussion focusing on the Thursday-Friday storm. The 5-Day Forecast was updated for the area except for Long Island/S CT.


Tomorrow And Thursday: Cooling Down

While the storm is exiting the area, the cold isn't moving in just yet. The cold is expected to move in by tomorrow night with some precipitation expected for the area tonight into tomorrow morning, with high temperatures tomorrow in the mid 30s to lower 40s across the area. Thursday will be a colder day as a cold air mass moves into the region once again, with high temperatures in the mid 20s to lower 30s across the area.


Thursday Night - Friday Storm: Uncertainty Continues

Yesterday, I mentioned how there are three possible scenarios, one of them bringing a big snowstorm to the west/north of the area and a wintry mix along the Interstate 95 corridor, another one of them bringing a significant snowstorm from the area into parts of New England, and another scenario where the storm intensifies too late and we see a widespread light to moderate snow event across the region. Today's models are still showing this uncertainty, though the western scenario that would bring a wintry mix for the area is unlikely at this time.

It appears that at this time, the main split is between a solution that would bring a significant snowstorm to the area and a solution where the storm intensifies too late, with a widespread light to moderate snow, though a western solution still cannot be ruled out. With every model consistently showing at least some snow, I have decided to include a 100% chance of snow in the 5-Day Forecast, as it still appears that at least some light snow should fall.

We have seen several different solutions today, with the NAM the most extreme at first, bringing a widespread 8-10+ inch snowstorm to the area and its latest run bringing at least 3-6 inches for the area. The SREF has been showing a further northwest and snowier solution, the GFS is showing a moderate snowstorm, and the ECMWF model is showing a weaker and drier solution. Due to the uncertainty, I decided to wait until tomorrow before going into forecasting snow accumulations and adding alerts, though there is at least some idea on what could happen. This storm is expected to move quickly, not lasting much more than 12 hours, preventing high snow accumulations well over a foot, though it still appears that the area will likely see accumulating snowfall with the drier solutions. It appears at this time that with the snowier solutions, a maximum snow potential of 8 to 12 inches may be possible, with a minimum of 1 to 3 inches, though this range should likely be narrowed down by tomorrow.

With all of the uncertainty, it is still too early to determine whether this will be a significant snowstorm for the area or not, though there is the potential for a snowstorm with at least 4 or more inches to affect the area between Thursday night and Friday afternoon. Stay tuned for more information on this storm over the next few days.

Jan 18, 2011 Storm Updates



***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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In the post below, storm updates will be posted on the snow and ice storm that is currently affecting the area.

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4:00 PM Update: Since this morning, the immediate NYC area and coastal southern Connecticut changed over to rain as expected, which was heavy at times and resulted in flooding in some places. In the western and northernmost parts of the area, however, temperatures stayed below or near freezing, and the precipitation failed to change over to rain, in fact these areas are still seeing freezing rain at this time as the storm is ending. There are no reports of final ice totals yet, however a significant ice storm was observed in the western and the northernmost parts of the area.

The precipitation is currently ending for the central and starting to end for the eastern parts of the area, however there is still another round of precipitation expected for tonight, which may bring more frozen precipitation for the western parts of the area. The storm will end by tomorrow afternoon.

Stay tuned for the next full update tonight, with more information for Friday's storm and the arctic air blast that will follow, likely bringing the coldest temperatures since January 2009 for most of the area.


7:15 AM Update: Overnight, the area saw light to moderate snow with accumulations generally over an inch away from the coast. 850 mb temperatures are currently above zero, however surface temperatures are still below freezing across most of the area, leading to freezing rain falling across most of the area except for Long Island, which has mainly changed over to rain.

Freezing rain will change over to rain first in the immediate NYC area later this morning, followed by southern Connecticut, with the most persistent freezing rain in interior SE NY and NW NJ. Freezing rain amounts between 0.1 and 0.3 inch are expected for southern Connecticut and NE NJ, with between 0.3 to as much as locally 0.6 inch of freezing rain for the western parts of the area, where freezing rain will be the main precipitation type.

Based on the current short term models and the radar appearance, it appears that the storm may move out by the early afternoon for the western and central parts of the area, which is earlier than previously expected. If this does happen, the western parts of the area may fail to change over to rain, and the immediate NYC area could be spared of significant snow melt. The same does not go for Long Island, however, which is expected to see at least an inch of rain, if not a little more.

The next update will be posted this afternoon, with more about this storm and about Friday's storm.

Monday, January 17, 2011

Jan 17, 2011: Snow And Ice Tomorrow


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Today brought mostly sunny skies to the area in the morning, however cloud cover started increasing by the afternoon ahead of a low pressure that is currently bringing snow and sleet to the central Mid Atlantic. This storm will continue to spread northwards, bringing a wintry mix to the area tonight into tomorrow. This is not the end of the snow potentials, however, as by the late week yet another storm threatens to bring a significant snowstorm to parts of the region, potentially including parts of the NYC area.


Tonight Into Tomorrow: Snow/Sleet To Rain/Freezing Rain

We are currently seeing a widespread area of heavy precipitation in the eastern Mid Atlantic, spreading northwards into the exiting cold air mass. A cold air damming scenario is setting up, where despite the lack of cold air, the area will start out as snow, then change over to rain in the central and eastern parts of the area with freezing rain further inland.


Forecast For The Area: In Long Island, the storm will only bring a brief light snowfall, as the storm will quickly warm things up, changing the coast over to rain by the morning with up to 1 inch of snow expected. Further west though, into New York City, NE NJ and southern Connecticut, the snow is expected to last a little longer, with a wintry mix in the morning hours followed by rain in the late morning into the afternoon. At least 1 to 3 inches of snow are expected, with up to 0.1 inch of freezing rain north and west of NYC.

For the western parts of the area, the storm will start out as snow, which will become moderate at times, bringing a total of 3 to 5 inches of snow. By the late morning, a wintry mix is expected to fall, but as the temperatures may never get above freezing near the surface in some locations, parts of the area will continue to see freezing rain into the afternoon hours, leading to significant ice accumulations between 0.2 and 0.4 inch possible.


This has the potential to be a dangerous ice storm for the western parts of the area. There will not be an update posted tomorrow morning, instead the next update will be posted tomorrow afternoon.


Late Week Storm: Big Storm Potential

Yesterday's models and even some of today's models continued to show the potential for a weak storm on Friday affecting the area with light snow, however today's runs took a turn to the other solution, now showing a big storm affecting the region. The GGEM and NAM models are the most extreme with this, with the NAM showing what would likely be a mix/rain event for the area, and the GGEM showing a heavy snow event with mixing for the central and eastern parts of the area. While it is still too early to determine which one is the most likely, both of these solutions cannot be ruled out at this time.

So far this winter, when we had potentials for big storms, most of the times they ended up verifying, and with the trends we are currently seeing with the models, it appears that this storm may not be an exception to that trend. On Thursday, we are looking at widespread snow from Oklahoma/Missouri into the Ohio Valley associated with a low pressure in the South, however the timing of the storm's phasing will make the difference between a moderate snow event mostly to the south/east of NYC, to a significant/major storm for the area into New England, to a major snowstorm for interior areas with a wintry mix for the area.

The earlier that this storm phases, the more likely it is to be stronger early on and track further west, bringing more of a mix for the area, and the later the storm phases, the more likely it is to produce a significant snowstorm for the area. At this time, the 00z NAM has an early phase, and ends up taking the storm through the central Mid Atlantic, bringing a wintry mix for the area and rain further south. This is the westernmost scenario at this time. The GGEM model has phasing taking place a little later, bringing a major snowstorm for the area into New England. The GFS right now is more progressive and has a later phase, however it has been trending closer to a big storm with each run, and it is possible that it could continue with this trend through tomorrow.

Based on the set up, it does appear that at least some snow will fall across the region, and at this time I went with a 70% chance of precipitation in the area. If there are no major changes, I will likely raise this to a 100% chance with tomorrow's update. At this time, I put snow in the 5-Day Forecast for the western/central parts of the area with a rain/snow mix further east, however this is subject to change, and it is possible that this storm could bring a rain/snow mix to most of the area, it could mainly stay to the south and east of the area with some light to moderate snow, or it could be a significant snow producer for the area. Stay tuned for more information on this storm and how it may affect the area.


Longer Range: Arctic Air Blast Moves In

The arctic air blast I have been tracking since early January remains on track for next weekend, as a very cold arctic air mass will follow behind the storm, then drop southeast to affect the region during the weekend. There is still some uncertainty on exactly how cold it gets, but the potential is there for low temperatures in the single digits for the area away from the coast with sub-zero lows inland for Saturday night, with high temperatures on Sunday potentially staying below 20 degrees for parts of, if not most of the area if the colder case scenario verifies. Stay tuned for more information on this time frame.

Jan 17, 2011 Morning Updates


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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While a full update will be posted tonight, including the final storm forecast for tonight into tomorrow, there were some changes this morning with the forecast that I will mention with the update below. In addition, the storm summary for the January 11-12 storm was posted this morning, and a new poll was opened for the potential impacts with the Friday storm.


Today: Warmer Than Previously Expected

The low temperatures last night ended up busting too far on the cold side, as despite the expectation for very cold temperatures, increased cloud cover prevented even interior areas from dropping below 10 degrees. Today is now expected to be warmer than yesterday's forecast, with high temperatures in the lower, potentially mid 20s inland, with mid 20s for the rest of the area. Some upper 20s cannot be ruled out from NYC and further south/SW.


Tonight into Tuesday - Colder/Snowier Solution Now Expected

As I was working on my discussion last night, the 00z NAM run came in much colder and snowier. While I thought that the NAM could be a bit too extreme, it continued with its cold solutions and the GFS/GGEM also trended much colder. With a faster start to the precipitation a possibility, the entire area is expected to see at least some snow to start, with accumulations up to 1 inch in Long Island, between 1 and 2 inches for NYC, 1.5 to 2.5 inches for NE NJ through southern Connecticut, and 2 to 5 inches for the interior parts of the area. At least 0.1 to 0.2 inch of freezing rain is possible for the immediate north/west suburbs of NYC, with 0.2 to 0.4 inch of freezing rain a possibility further inland, where the precipitation may stay frozen for the entire duration of the storm.

The 5-Day Forecast will be updated this afternoon, with my latest expectation for each part of the area. Stay tuned for more updates on this storm later this afternoon and tonight.


Late Week Storm: Big Storm Potential?

Yesterday, I mentioned how a low pressure is expected for Friday, however there are significant differences. The 00z GGEM run today showed a very strong storm, with what seems to be over 10 inches of snow for the central and western parts of the area with mixing issues for the eastern parts of the area. For reasons that I will discuss in more details later tonight, a big storm scenario is starting to become a better possibility, and while there is still uncertainty as some models still do not show this while others do, there is the potential for a significant storm to affect the area on Friday, which may bring a significant snowstorm to the area depending on the set up scenario. Stay tuned for more information on this storm and how it may affect the area.

January 11-12, 2011 Storm Summary

The winter of 2010-2011 so far has exceeded its expectations, producing more cold and snow than expected, including one of the biggest snowstorms on record for New York City on December 26-27, 2010. This time, New York City was spared from the heaviest snowfall, as the storm produced widespread 15-30 inches of snow for New England, however it was still enough for widespread heavy snow to affect the area, bringing this winter's snow totals above average for most of the area in only half of the winter.


Forecasting The Storm:


While forecasting this storm was easier than the December 26-27 storm, when all of the models caught on to the big snowstorm idea only one day before the storm, there were still some difficulties forecasting the storm, especially in the shorter range. It appeared that there was the potential for a storm to affect the area since early January, when it was first mentioned in my updated winter outlook. Later on, as it became apparent that the storm would affect the area, I discussed it in more details.

With this storm, there was a higher than usual confidence in the medium range that it would affect the area with snow. A set up with a primary low to the west and another one to the south suggested that even if the main coastal low misses the area, it will still bring at least some snow, supporting my decision to put certain snow in my forecast 4 days prior to the storm. By then, however, a split set up between the models that lasted until the day before the storm.

The global models, such as the GFS, GGEM and UKMET, were consistently east with the storm and showed much lighter QPF maximums, bringing barely 2-4 inches of snow to the area and sparing New England of most of the heavy snow. The NAM and the short range models, however, showed a further west and wetter scenario than the global models. The short range models typically handle this type of an event better, and we also had a similar case with the 12/26 blizzard where even on the day before the storm, the GGEM and UKMET were still too far east, therefore I used the western solutions, especially the NAM for my forecasts.

Two days before the storm, the NAM trended significantly wetter, highlighting the potential of as much as 2 feet of snow in southern New England. Even though it did not have much support from other models, the short range models also had the idea of high precipitation totals, and I included this potential in my snow map, as well as a widespread 15+ inch area from Long Island into southern New England. The majority of southern New England ended up seeing over 15-20 inches of snow with amounts locally as high as 30-35 inches of snow. In my January 8 update, I mentioned the potential of 8 to 14 inches of snow for the immediate NYC area, and kept that forecast the same with only minor changes. On the day that the storm started, the GFS, GGEM and UKMET models finally caught on to the expected scenario, showing a much further west solution.


Storm History:


**The radar image to the left shows the storm as the coastal low began taking over as the main storm, around 11 PM.**


Prior to reaching the area, the storm also had a significant impact in other parts of the US. In the southern United States, it moved from west to east near the coast of the Gulf of Mexico, producing a significant ice and snow storm, resulting in snow cover in every US state except for Florida. As the coastal low lost most of its heavier precipitation once reaching Florida and the Carolinas, another weak low pressure became the primary low further north. This primary low then moved northeast, reaching Ohio, while producing a large area of moderate to heavy snow moving east through Pennsylvania.

While the radar appearance of the coastal low was rather unimpressive on Tuesday afternoon, things quickly began to change by the evening. The coastal low started to intensify faster, becoming the main storm, and as the snow entered the area from the west, the direction in which the precipitation came from changed from west to south as the coastal low continued to organize. Widespread heavy snow developed in New Jersey with rain and thunderstorms near the immediate coast, moving northeast to affect the area. Through the early to mid overnight hours, heavy snow continued to affect the area with snow rates generally between 1 and 2 inches per hour, lower in some places and higher in others.

The snow was quick to end for places west of NYC, already moving out with sunshine by the morning hours. For places east of NYC, however, it was a different story. As the low pressure quickly intensified, it moved over eastern Long Island, with a heavy deformation snow band affecting central Long Island and western Connecticut, and thundersnow was also observed. The storm then slowed down near the coast of Massachusetts while producing lighter snowfall for the eastern parts of the area through the afternoon hours. By the evening, most of the area was dry.


Storm's Aftermath:

The storm brought widespread wintry precipitation from the southern and central United States into most of the eastern United States, however the worst of the storm focused on New England. Heavy snow with blizzard conditions and thundersnow was observed there, and snow continued through most of January 12th as the storm significantly slowed down off the coast of Massachusetts. Snow totals across most of southern and central New England were over 15 inches with 20+ inch reports also widespread.

In the area, the heaviest snowfall ended up in southern Connecticut, where the heaviest banding set up. Snow totals ended up over 15 inches for almost all of southern Connecticut, with 20+ inch reports also widespread. The biggest reported snow total in the area was 30.5 inches in North Haven. Long Island saw more of a contrast between the lighter and the heavier snowfall, with amounts anywhere from 6 to 18 inches and the heavier amounts focusing on Suffolk county, where there was a report of 18.6 inches in Farmingville. Lighter snow totals were reported further west, with New York City reporting anywhere from 6 to 12 inches of snow and northern New Jersey reporting 5 to 10 inches of snow.

While this storm was not a historic snowstorm in the immediate New York City area, having more significant impacts in southern Connecticut into New England, it was yet another significant snowstorm of a snowy winter for the area, bringing snowfall above the average for the entire winter in most of the area.


Polls:

NYC Area Weather had two polls active in the days before the storm, asking visitors about the impact of the storm in the area and how much snow New York City will see. Here are the total votes for each poll, with the correct answer(s) bolded in black:


What will the area see on 1/11-12? (49 votes)

0 votes - Storm well offshore, snow showers
4 votes - Storm clips NYC with light snow
40 votes - Heavy snow in NYC
5 votes - Too close to coast, rain/snow mix


How much snow will NYC see? (51 votes)

2 votes - 1 to 3 inches
3 votes - 3 to 6 inches
18 votes - 6 to 10 inches
13 votes - 10 to 15 inches
15 votes - 15+ inches

Sunday, January 16, 2011

Jan 16, 2011: Forecast For Tuesday's Storm


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Today brought mostly to partly sunny skies to the area with high temperatures generally in the lower to mid 30s across the area. A cold air mass is currently over the area, which will lead to a brief yet intense cold spell, with what may be the coldest night of the winter tonight. Tomorrow will be a very cold day, with high temperatures struggling into the 20s, however another storm that will move in will bring a wintry mix for the area on Tuesday, with potentially significant amounts of freezing rain inland.


Tonight's Forecast: With mostly clear skies tonight and a high pressure nearby, temperatures will steadily drop tonight, reaching their coldest point yet in most of the area. Low temperatures are expected to be between -5 and 4 degrees inland, in the lower to upper 0s for the north/west suburbs of NYC and southern Connecticut, mid 0s to lower 10s for Long Island, and lower to mid 10s in NYC.

Tomorrow's Outlook:

As the high pressure will be near the area, a generally light and variable wind is expected. The cold air mass will still be in place, leading to high temperatures being at their coldest so far this winter, in the upper 10s to lower 20s inland and in the lower to mid 20s for the rest of the area.

Note that the interior areas, the warmer spots near/south of NYC and parts of Long Island may be slightly warmer than the map is showing.


Monday Night - Tuesday: Wintry Mix To Rain

A coastal low that will start to take shape late tomorrow off the Southeast coast will affect the area by the overnight hours. Most of the models seem to be in general agreement with the storm track with some minor differences, however it does appear that at least some snow falls over most of the area, with a cold air damming scenario leading to freezing rain further inland. The NAM was an outlier today, showing a much further east and weaker solution with barely 0.25" QPF in NYC, however it seems to have corrected itself in its latest 00z run and trended wetter, a little faster, stronger and colder at the same time. While its solution may be a bit too extreme, it also highlights the potential for snow to accumulate in the start of the storm, with more significant freezing rain inland.


Forecast for the area: Light snow is expected to begin across most of the area around 12 AM, a little later in places further north/east, and will quickly change over to rain near the coast by the morning with less than 1/2 inch of snow expected. The rain may be heavy at times, with 1 to 1.5 inch of rain expected.

In the immediate NYC area, snow will likely persist until the morning hours, when a brief period of freezing rain is expected before changing over to rain. Snow accumulations up to or near 1 inch are expected for NYC, with near 1-2 inches and less than 0.1 inch of freezing rain in the north/west suburbs. The rain may also be heavy at times in the afternoon and evening, with rain totals between 0.75 and 1.25 inch possible.

Towards western Bergen, western Passaic, Rockland, Morris counties and further northwest, however, it will be a different story. The snow may become moderate at times by the morning, with at least 2 to 4 inches of snow expected. 850 mb temperatures will rise above freezing, however the cold will remain trapped near the surface, resulting in freezing rain becoming the main precipitation type by the late morning. Parts of the interior areas will change over to rain, however it is possible that parts of the interior areas may continue to see freezing rain with no changeover to rain. As a result, I issued a Freezing Rain Alert for the interior parts of the area, highlighting the potential for freezing rain amounts to reach 0.25 inch.


My preliminary scenario map for this storm was posted in the top left. There is still some slight uncertainty with the storm, and it is possible that slight changes could be made by the time that the final discussion and map will be posted tomorrow night, including potentially raising the expected snow amounts further inland. Stay tuned for more updates on this storm tomorrow.


Longer Range: Uncertainty Increases

Behind the storm, except for Wednesday which will bring even warmer temperatures into the lower 40 for parts of the area, it is expected to get colder again, with high temperatures once again returning into the 20s by Thursday, however there is more uncertainty for Friday regarding a storm that may affect the region. The ECMWF was the highlight of today's models, twice showing a big snowstorm for the area around Sunday, but even though there is not much support for the ECMWF's solution at this time, it will continue to be watched until there is better agreement with the models.

It appears that we will see a wave of low pressure on Friday, however what happens with it on Friday and afterwards is a question. Most of the models are suppressed with this, keeping most of the snow to the south of the area with only light snow in the immediate NYC area, however some solutions are further north, and the ECMWF have a different scenario, showing the main storm on Sunday, not Friday. There is still a lot of uncertainty at this time with this time frame, so stay tuned for more information on this potential storm over the next few days.

Saturday, January 15, 2011

Jan 15, 2011: Wintry Mix For Tuesday


***This post is from 2011. Please visit the MAIN PAGE to see the latest forecasts for January 2012.


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Note: As I have been focusing more on the snow/ice threat for Tuesday, the storm summary for the January 11-12 storm was not posted tonight, however it will be posted tomorrow. In addition, the 5-Day Forecast page was updated for the area except for Long Island/S CT.

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Today was a partly to mostly cloudy day across the area, with more cloudy skies by the afternoon and scattered snow showers, especially north of New York City as a result of a low pressure that brought more widespread snowfall to the north of the area. Another cold air mass is currently moving into the area, and while tomorrow will not be very cold, tomorrow night is expected to be the coldest night so far this winter, with sub-zero low temperatures possible once again inland and high temperatures on Monday only in the upper 10s to mid 20s. As cold as this sounds, it is possible that even these lows may not be the coldest temperatures of the winter yet.


Tomorrow's Outlook:

Tomorrow will be a mostly to partly sunny day across the area with high temperatures once again above the 30 degree mark for parts of the area. High temperatures tomorrow will be in the upper 20s to lower 30s inland and in the lower to mid 30s for the rest of the area with a west wind expected.

As another arctic air mass moves into the area, low temperatures will quickly drop overnight, and may be even colder than those of yesterday morning according to the GFS model. There is some uncertainty with exactly how cold it gets, but the potential is there once again for interior areas to drop slighty below zero degrees, with single digits for most of the area away from the coast for Monday morning including the colder spots in eastern Long Island.


Early-Mid Week: Cold Monday Gives Way To A Wintry Mess On Tuesday

The week will start out on a very cold note, with high temperatures on Monday only peaking in the upper 10s to lower 20s inland and in the lower to mid 20s for the rest of the area. A few upper 20s are possible in the warmer spots from NYC and further south/SW, however these readings should not be widespread. An approaching storm, however, will change this, temporarily pushing out the cold air.


Model Analysis: There is still uncertainty with the exact set up on this event, with the models still showing a variety of solutions ranging from a low pressure hugging the coast with heavy rain and very little frozen precipitation as shown on the 18z NAM, to a coastal low that is further east and brings 1-3 inches of snow for the area on Monday morning followed by freezing rain/rain north and west of NYC as shown on the GFS. At this time, the GFS solution is the coldest one, with the other models showing warmer solutions. The 18z NAM, however, may have been perhaps a bit too warm, and for this forecast I am using a solution in between the GFS and the NAM but considering both extremes as possibilities.


Forecast For The Area: On Monday night, a low pressure off the Southeast coast along with another weak low pressure near the Great Lakes will push out the cold air mass, leading to warming temperatures on Monday night. Despite 850 mb temperatures warming up, we should see a cold air damming scenario, meaning that not all of the cold air gets pushed out. Light snow is expected to enter the area on Monday night, however any light snow should be brief for places south/east of New York City and will quickly change over to rain. For the immediate NYC area, the cold will hold around a little longer but will not be enough to keep the precipitation frozen the whole time, and while there is still uncertainty on the start of the event, it appears at this time that any snow to start should be light, with accumulations up to 1-2 inches, especially north and west of NYC, changing over to sleet/freezing rain by the morning and rain by the late morning. This is still subject to change though.

For the interior areas, however, the cold will stick around the longest, and after some light to potentially moderate snow to start, with accumulations potentially in the 1 to 3 inch range in the snowier solution, a longer period of freezing rain and/or sleet is expected than in areas closer to the coast. The interior area may also change over to at least some rain at this time, however depending on the storm set up, some places in the interior may not change over to rain at all and would stay with freezing rain in the colder scenario. For now, I put rain and freezing rain in the 5-Day Forecast for Tuesday afternoon, however this is subject to change. There could be enough freezing rain to lead to some ice accumulations, and I may issue a Freezing Rain Alert tomorrow.


There is still some uncertainty with this storm, and it is possible that the scenario may change. It is possible that we may see a warmer scenario, where NYC warms up into the lower to mid 40s with barely any frozen precipitation to start and heavy rain falling, ot we could see a colder scenario where the central and eastern parts of the area see at least 1-2 inches of snow followed by freezing rain persisting inland and only moderate rain for NYC further east. Stay tuned for more information on this storm and what impact it will have on the area.


Late Week - Weekend: Rain/Snow Possible Friday, Then Extreme Cold

While Wednesday is expected to be another relatively mild day, with temperatures similar to, if not slightly coler or warmer than those of Tuesday, in the mid 30s to lower 40s, yet another cold air mass will move into the area with cold overnight lows on Wednesday night, but not as cold as those of this morning and yesterday morning. High temperatures will return into the 20s for Thursday, however there is the possibility that another storm affects the area on Friday.

All of the models now show the Friday storm, and it is more of a question of how the storm will affect the area. The GFS only brings light snow to the area with the storm intensifying further offshore, however the ECMWF shows a solution completely different, close enough to the coast to bring a wintry mix for the immediate NYC area and more snow inland. While an inland track is unlikely at this time, it is a possibility that this storm could track over the cities, bringing mixing issues for parts of the area, but a plain rain storm is not expected at this time. A storm track that brings plain snow to the area is also a possibility. There is still uncertainty on this time frame, however, and some changes are expected with the models over the next few days. Stay tuned for more information on this storm.

Behind this storm, it appears that we may see the coldest temperatures of this winter and perhaps the biggest arctic outbreak since January 2009 if the coldest solutions verify. Most of the models bring 850 mb temperatures near or even slightly below -20c for the area, and while there is uncertainty on exactly how cold it gets, it is possible that most of the area only sees high temperatures in the 10s, with lows below zero degrees inland and the zero degree line potentially getting as far as the immediate N/W suburbs of NYC in the colder case scenario. Once again, it is still a possibility that the extreme scenario doesn't play out, and high temperatures only end up in the upper 10s to mid 20s range with low temperatures in the mid 0s to mid 10s, however at this time the cold scenario is starting to look more likely than it did yesterday. Stay tuned for more information in this time frame.