Thursday, March 31, 2011

3/31/11 Noon: Last Minute Shift Changes Forecast

10 PM: Due to technical difficulties, no full update was posted tonight. Tonight's forecast remains the same for the storm. The 5-Day Forecast page was updated for now through Sunday, and tomorrow's update will discuss the forecast through Tuesday in more details.

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6:20 PM: Over the last 1-2 hours, precipitation began to intensify especially south, east and NE of NYC, with snow and sleet mixing with the rain in parts of the area but with no accumulations. The heaviest precipitation will not last long, and occasional rain showers will continue through the rest of this evening, mixing with light snow and sleet at times.

For tonight's storm, however, a last minute shift on the models has significant changed the outcome of the storm across the region and especially in the area. Two days ago, the models already showed the storm close to its peak intensity when near the area, which would've been a supportive solution for a heavy wet snowfall in NYC but was an unlikely solution. Yesterday's models delayed the intenficiation of the storm, allowing warmer 850 mb temperatures to push further north as the storm is developing, resulting in heavy rain for the eastern parts of the area and a moderate snowstorm further west. Today's models, however, trended even more east and weaker to the point where the storm fails to become anything significant for anyone outside of central/northern New England.

As such, I downgraded the Snow Watch to a Light Snow Alert for the interior parts of the area and removed the Rain Watch for Long Island. The latest expectation, which will be posted in the 5-Day Forecast page shortly, expects occasional rain/snow/sleet showers to continue through this evening, with steadier rain developing after midnight, mixing with snow further north and west of NYC. The precipitation will become moderate at times, especially further east, falling as rain for NYC and further east while falling as snow towards Orange, Sussex and West Passaic counties. The snow line may shift further southeast by Friday morning, potentially reaching the immediate north/west suburbs of NYC, before ending by at least noon.

Rainfall amounts for the eastern parts of the area are expected to end up between 1/4 and 3/4 inch, with snowfall amounts between 1 and 4 inches further inland towards Sussex, West Passaic and Orange counties, with the highest amounts in the higher elevations. Stay tuned for more updates on this storm tonight, as well as an update on a storm that will bring warmth and potentially strong thunderstorms to the area on Tuesday and Tuesday night.

Wednesday, March 30, 2011

Mar 30, 2011: April Fool's Snowstorm

As a storm approached the area from the west, cloud cover steadily increased throughout the day. Temperatures ended up warmer than expected, peaking in the upper 40s to lower 50s east of NYC and in the lower to mid 50s further west. Currently, we are seeing light precipitation over the area that is not reaching the ground in some cases, though the storm will continue to move east, bringing light to moderate rain tonight, mixing with light snow north and west of NYC. While little to no accumulations are expected tonight, Friday will be an entirely different story in the interior parts of the area as an early April nor'easter brings a major snowstorm to the interior Northeast with heavy rainfall for the coast, including NYC.


Tomorrow's Outlook:

Tomorrow will bring cloudy skies with occasional showers to the area. High temperatures will generally be in the lower to mid 40s across the area, with the warmest temperatures in the immediate NYC area. An east wind is expected.


Tomorrow Night - Friday: Snow Inland, Heavy Rain In NYC

The winter-like pattern we entered around March 21st has not ended just yet, as yet another snowstorm is expected to affect the interior parts of the area, with a major snowstorm for the interior parts of the Northeast with as much as a foot or more of snow expected there. For the area, however, except for the higher elevations further northwest this will not be a significant snowstorm, and in fact closer to the coast, including NYC, the main risk from this storm is heavy rainfall between 1 and 1.5 inches. Below, I will explain in more details the expected scenario for this storm.


Storm Set Up: In early April, the NYC area needs a very favorable set up in order for there to be a widespread accumulating snowstorm. With this storm, however, many of these ingredients are missing. There is no strong cold air mass in place, and in addition, there is no high pressure to the north of the storm to keep the cold air in place. As a result, even if the storm takes a track that would be favorable for a major snowstorm in NYC in January, it would most likely produce rain with this storm. Should there be a major snowstorm in the NYC area like yesterday's models suggested, the storm would have to intensify early enough that it would bring colder 850 mb temperatures to the area, which combined with heavy precipitation, would result in a heavy wet snow, however this solution is not expected to happen.

Forecast: Overall, we are looking at a coastal nor'easter tracking from southeastern Virginia up the coast towards Cape Cod and southeastern Maine. As the storm intensifies, it will become colder with a more widespread heavy snow area developing from northeastern Pennsylvania through interior New England.

For the area, the storms should begin late on Thursday night with rain moving in. As precipitation intensifies, a changeover to snow is expected for the northwestern parts of the area, especially in Sussex and Orange counties, which may be heavy at times. Meanwhile, moderate to heavy rain will develop in New York City, Long Island and southern Connecticut along with increasing winds. Light snow will likely fall at first, especially north and west of NYC, however at least in the immediate NYC area little to no accumulations are expected.

The storm is expected to end by the late morning hours, with dry conditions by the afternoon along with increasingly windy conditions. The interior parts of the area may also mix with rain towards the end of the storm, though at this time snow is expected to be the dominant precipitation type inland.

By the time that the storm ends, at least 3 to 6 inches of heavy wet snow are possible for Sussex and Orange counties, locally higher depending on elevation, with less accumulations further east, especially depending on elevation. Some light snow is possible just north and west of NYC, but the main precipitation type will be rain. Rainfall amounts in NYC and Long Island may reach 1 to 1.5 inches, therefore I issued a Rain Watch, which will likely be upgraded to a warning tomorrow.


Uncertainty: It is important to note that there is still some slight uncertainty, and the solution mentioned above is not final yet. Slight changes are possible, such as increasing or reducing snow accumulations inland and potentially increasing forecast snow amounts in the immediate NYC area, however significant snow accumulations are not expected in NYC. Stay tuned for more information on this storm tomorrow, as well as a warm up for early to mid next week that may even bring thunderstorms to the area.


Mar 30, 2011 Evening Update

7:00 PM: The first storm that was expected for tonight is currently in Pennsylvania, producing rain and moderate to heavy snow. While heavy precipitation is not expected to fall in the area tonight, precipitation does seem to be heavier than the models are showing. Moderate precipitation will fall in the area tonight, which should be mainly rain but with snow also falling north and west of NYC and potentially a few flakes in NYC itself. At this time, very little, if any, accumulations are expected for the interior parts of the area, though especially if a heavy burst of snow falls tonight, light accumulations cannot be ruled out for the higher elevations. More updates on this storm will be posted tonight.

Stay tuned for more information tonight on the storm for Thursday night and Friday. There continues to be uncertainty, but there is enough confidence for a Snow Watch for the interior parts of the area and a Rain Watch for Long Island, where 1 to 1.5 inches of rain may fall.

Tuesday, March 29, 2011

Mar 29, 2011: Snow Potential Friday, But Will It Happen?

As the cold air mass over the region continued to weaken, temperatures today were once again warmer than yesterday, peaking in the mid 40s inland and in the upper 40s for the rest of the area with a few lower 50s in the immediate NYC area. Today brought sunny skies once again to the area, however tomorrow will end this stretch of sunny days as a storm approaches the region.

This storm is not expected to affect the area at this time with much more than light rain/snow showers on Wednesday night, however there may be a more significant storm on Friday. There is still uncertainty with Friday's storm, and it is possible that if the right conditions fall in place, the storm may produce a heavy wet snow north/west of NYC, however it is a possibility that this may fail to become anything significant for the area. Below, I will discuss in more details the possibilities for this storm and what may happen in the area.


Tomorrow's Outlook:

Tomorrow will bring increasing clouds to the area as a storm approaches from the souhtwest. A few showers are possible towards the evening, but most of the light precipitation from this storm should fall in the overight hours. High temperatures will continue the warming trend, peaking in the upper 40s to lower 50s for the western parts of the area, lower 50s in the immediate NYC area, and in the mid to upper 40s for the eastern parts of the area.


Wednesday Night - Thursday: Weak Storm Potential

Yesterday, every model kept the storm on Wednesday night to the south of the area, with only a few rain/snow showers at most. Today, however, especially with the NAM, we are seeing two potential scenarios for this storm. The difference between these scenarios is not a big one for the area for this storm, but it may have a greater impact on Friday's storm, which will be discussed in more details below.

At this time, a weak storm is expected to move off the coast of North Carolina, bringing moderate rainfall to the Mid Atlantic. Precipitation is expected to make it far north enough to bring at least light rain/snow showers to the area on Wednesday night, which has been mentioned in the updated 5-Day Forecast, which is not expected to amount to anything significant, most likely up to at least 0.1" QPF. Even if the western parts of the area see a steady light snow, due to warm surface temperatures, accumulations are not expected.

The GFS mean, however, has been showing a wetter and stronger storm on Wednesday night, as well as the NAM. These runs would bring slightly more precipitation into the area in the form of snow early on Thursday morning north/west of NYC. This solution is unlikely at this time, but given the latest model difficulties in handling the storm, it will be watched.


Thursday Night - Friday Afternoon: April Fool's Snowstorm?

Up until yesterday, the models have had a lot of difficulties handling this storm, with some of them showing the storm well west of the area, others such as the UKMET showing a very intense storm, and others such as the CMC taking the storm out to sea. Today's models began converging on a solution, however this solution, should it verify, would bring a significant snowstorm north and west of NYC.

In this scenario, snow would begin falling after midnight on Thursday night, becoming heavy at times by Friday morning while mixing with rain and ending by early Friday afternoon. Most notably, the GGEM, ECMWF, and the 06z/12z runs of the GFS show significant snowfall for the interior parts of the area with the GFS even showing snow into NYC, and should these scenarios verify, as much as 10-12 inches of wet snow may accumulate towards Sussex and Orange counties.

There are other potentials, however, including the storm intensifying later, bringing in warmer temperatures with mostly rain falling for most of the area ending as a wet accumulating snowfall inland. The NAM and GEFS show the storm failing to become anything significant, and instead being absorbed by the stronger Wednesday storm. This solution is the less likely one at this time, but it will be watched.

Overall, there is still a lot of uncertainty with this storm, but a potentially significant late season snowstorm may be possible north and west of NYC. Stay tuned for more information on this storm and how it may affect the area.

Mar 29, 2011 Polls

Before the March 23-24 storm, I opened a poll about whether New York City will see snow or not. The results to this poll have been posted below, with the correct answer bolded:


Will NYC see snow on 3/24? (22 votes)

6 votes - No
1 vote - A few snow showers
6 votes - Yes, but no accumulations
9 votes - Yes, with accumulations


I have opened a new poll for Friday's storm, asking about the precipitation type and any potential snow accumulations in NYC. This poll will close on Thursday afternoon, 2 days from now. Tonight's update will discuss in more details what seems to be an increasing threat for an accumulating late season snowstorm in parts of the area for Friday.

Monday, March 28, 2011

Mar 28, 2011: Significant Storm Potential Friday

Note: The 5-Day Forecast was partially updated, through Thursday.

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Sunny skies continued once again across the area as temperatures slightly warmed up from yesteday, reaching the lower to mid 40s inlad and in the mid to upper 40s for the rest of the area, which was slightly warmer than expected. Overnight lows also failed to reach the forecast, staying above 20 degrees for most of the area.

With the latest models finally converging on a solution for Wednesday night's storm, it appears that this storm will stay to the south of the area, bringing no more than scattered rain/snow showers for the southern parts of the area. By Friday and Saturday, however, it appears that a more significant storm may affect the region, and while there continues to be a lot of uncertainty regarding the smaller details of the storm, there is the potential for additional rain and potentially snow to fall in the area on Friday/Saturday.


Tomorrow's Outlook:

After chilly temperatures tonight, which will drop into the lower to upper 20s except for NYC, which should see lows in the lower 30s, tomorrow will bring mostly to partly sunny skies across the area with a breezy NW wind expected once again. High temperatures will peak in the lower to mid 40s inland and in the mid to upper 40s for the rest of the area, and places especially near NYC and further southwest may even reach the 50 degree mark.


Wednesday And Beyond: Storm To South, Another Storm On Saturday

On Wednesday, the models originally suggested that a storm might track far north enough to bring light rain/snow to the area with accumulations possible inland. As today's models began converging on a solution, however, they trended well south of their solutions yesterday, and now keep most of the area dry other than a few rain/snow showers. I reflected this in the 5-Day Forecast, showing mostly cloudy skies with no precipitation for the area on Wednesday night.

By Friday, the models have consistently been showing a storm moving up the coast, however where it goes from there, how strong it gets and the timing are still uncertain, with solutions ranging from a significant snowstorm north and west of NYC on the 18z GFS to a storm missing the area to the east of the GGEM. There are still a lot of uncertainties with this storm, but with issues such as a lack of a strong cold air mass, at this time a mostly rain storm is favored over snow for NYC and the coastal areas, with a snow potential further inland. Snow is still a possibility in NYC though, and it's possible that the storm fails to become anything significant like some models have been showing, and the models will be monitored over the next several days. Stay tuned for more information on this storm.

Sunday, March 27, 2011

Mar 27, 2011: Two Storms, A Lot Of Confusion

As a very cold air mass for this time of the year continues to sit over the Northeast, suppressing a snowstorm well south of NYC and even south of Philadelphia, bringing a widespread light accumulating snowfall to Virginia, today brought mainly sunny skies to the area once again with warmer temperatures than yesterday, peaking in the lower to mid 40s across the area. These temperatures are the warmest that parts of the area has seen since last Tuesday, but they are still at least 5-10 degrees below the average highs for this time of the year.*

The cold air mass will gradually weaken tomorrow and on Tuesday, bringing warmer temperatures, however there are two storm potentials next week, one on Wednesday night and another one for Friday night into Saturday. The models are somewhat similar for Wednesday's storm, with snow possible once again for parts of the area especially north and west of NYC, but by the late week, there is much higher uncertainty as the potential for a significant storm exists but with each model showing a completely different scenario.


Tonight and tomorrow's Outlook:

As clear skies continue tonight, very cold temperatures are expected across the area. Temperatures are expected to drop steadily, reaching the lower to mid 10s inland and in the upper 10s to mid 20s across the rest of the area, with the warmest temperatures in NYC. Low temperatures may even reach the upper 10s as far as the immediate north/west suburbs of NYC.

Tomorrow will bring sunny skies once again with chilly temperatures, peaking in the upper 30s to lower 40s inland and in the lower 40s for the rest of the area, with a few mid 40s in the immediate NYC area. A breezy NW wind is expected, which may gust between 20-30 mph especially near the coast.


Tuesday - Thursday: Warmer Tuesday, Snow Again Wednesday Night?

Tuesday will continue with the warmer temperatures, with mostly sunny skies expected to continue. High temperatures are expected to reach the mid 40s for the interior parts of the area, and may even reach the 50 degree mark in parts of the immediate NYC area. Despite this being the warmest temperature in NYC in a week, since last Tuesday, it's still below the average high temperature for this time of the year.

Wednesday will bring milder temperatures than today once again, also expected to reach the mid to upper 40s in the immediate NYC area, however increasing clouds are expected ahead of the next storm. A high pressure to the north of the storm will block it from tracking too far north, but the storm will not be forced as far south as today's storm, and it may affect the area with precipitation. Most of it will fall during Wednesday night, and the models are showing 850 mb temperatures below freezing. While surface temperatures are an issue on some models, and some models don't even show any precipitation for the area, there is the potential for snow to fall once again across parts of the area, especially north and west of NYC. It is possible that it rains, or that no precipitation falls at all, but should it snow, accumulations, if any, would stay on the light side. Stay tuned for more information on this storm and how it may affect the area.


Late Week Into Weekend: More Significant Storm?

The latest models are showing an unusually large split for the longer range, with some not showing a significant storm, others such as the UKMET showing a very intense storm tracking well west of the area, and others such as the 18z GFS showing a significant snowstorm for the area, even showing at least 6 inches of snow for NYC, if not even more. While the 18z GFS will most likely not verify, there is the potential for a significant storm to affect the region. At this time, should we see a significant storm, rain would be favored over snow for the coastal areas including NYC with the better potential for a significant snowstorm well inland if the storm takes a track at least just east of NYC or west from there, but if the storm ends up taking a path east enough of the area to bring cold temperatures into the area but west enough to bring precipitation into the area, the result may be snow for parts of the area.

At this time, with each model showing a different scenario, it is difficult to tell exactly what this storm might do and whether it will bring snow, rain or both to NYC, and the exact timing is also uncertain, but there is the potential for a significant storm to affect the area between Friday and Sunday, and while rain is favored over snow at this time for NYC, snow cannot be ruled out. Stay tuned for more information on this storm and how it may affect the area.

Saturday, March 26, 2011

**No update posted 3/26/11**

No update was posted tonight. The next update will be posted tomorrow, focusing on two potential storms late next week and how they may affect the area.

Friday, March 25, 2011

Mar 25, 2011: Cold And Dry Weekend

Note: The 5-Day Forecast was not updated tonight, however there are no changes in the expectations from last night's forecast.

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As a very cold air mass for this time of the year continues to move in, high temperatures today were once again on the chilly side, ending up in the upper 30s inland and in the lower to mid 40s for the rest of the area. Temperatures will stay cold through the weekend, with high temperatures cooling down even more tomorrow with widespread low temperatures in the 10s expected on Sunday night, however afterwards temperatures will begin to warm up, with the next storm expected to affect the area late next week.


Tomorrow's Outlook:

Tomorrow will bring sunny to mostly sunny skies across the area. A breezy NW wind is expected. High temperatures will be slightly cooler than today, peaking in the upper 30s to lower 40s in the immediate NYC area and further east, with mid to upper 30s inland. It is possible that temperatures end up slightly warmer than expected in the immediate NYC area into parts of southern Connecticut and Long Island.



Sunday And Next Week: Warming Up

As a storm stays to the south of the area on Sunday, bringing a late season snowstorm to parts of Virginia, temperatures will again stay on the cold side, peaking in the upper 30s to lower 40s across the area. Sunday night will be very cold, with low temperatures in the lower 10s inland and in the upper 10s as far as the immediate N/W suburbs of NYC.

More information will be posted on the longer range with tomorrow's update, including warming temperatures and a storm late next week.

Thursday, March 24, 2011

Mar 24, 2011: Snow Over, January-Like Cold Next

Yesterday's storm was an unusually difficult storm to forecast, with many uncertainties regarding precipitation types and amounts lasting even through when the storm was already affecting the area. The model performance for this storm was not a very good one, with the GFS busting way too far north, bringing mixing well into Connecticut, and the NAM model was too wet.

After I posted my final update last night, the storm in Pennsylvania continued to move east southeast and there was no indication that anything else would fall, however an unexpected round of snow quickly developed after midnight, bringing a widespread light to moderate snowfall to the NYC area, and with temperatures near or below freezing, accumulations were observed across the entire area, with even an inch of snow observed in Central Park. Further west towards northwestern New Jersey, the highest accumulations were observed, with as much as 10-11 inches in portions of Morris and Sussex counties.

As the storm exited the area, today brought partly cloudy skies with snow showers early, with high temperatures below the average for this time of the year, peaking in the lower to mid 40s across the area, resulting in the snow quickly melting across the central and eastern parts of the area. Despite no snow expected over the next week, the main story will be the January-like temperatures expected, with high temperatures failing to reach the 40 degree mark in parts of the area over the next few days.


Tomorrow's Outlook:

After cold temperatures tonight, which will get as low as the mid 10s inland and in the mid to upper 20s in NYC, tomorrow will bring mostly sunny skies to the area. High temperatures are expected to be similar to, if not slightly colder than today, peaking in the upper 30s to lower 40s inland and in the lower 40s for the rest of the area. A few mid 40s are expected for NYC and further southwest. A NW wind is expected.



Weekend Outlook: Cold Continues, Snow South Of NYC

The cold is expected to continue through the weekend across the region, with enough cold air and suppression that the next snowstorm will stay south of NYC and even mostly south of Philadelphia. Friday night will bring even colder temperatures than tonight, which may even get as low as the lower 10s inland with 10s possible as far as the immediate north/west suburbs of NYC. Saturday is expected to bring mostly sunny skies again with high temperatures slightly colder than those of tomorrow, peaking in the upper 30s to lower 40s across the area.

**Correction: The date on the map should say March 26-27, not March 24-26.**

By Saturday night, a quick moving system will move towards Arkansas and Tennessee, bringing a widespread area of light to moderate snow into the Ohio Valley. The snow, however, will be blocked from moving east and ENE into the area and will be forced to stay south. Unlike yesterday's storm, when there was still uncertainty on the storm's exact track and snow areas, it is certain with this storm that there will be suppression strong enough to keep the snow south of the Northeast. It is possible that it might trend a little north to bring some light snow to NYC, but most of the snow will stay to the south of NYC.


The NAM is likely overdoing the southern extent, showing a snowstorm for southern/central Virginia, and I went with a scenario closer to the GGEM and GFS, showing the highest snow accumulation potential from the West Virginia/western Virginia mountains where over 4 inches of snow are possible. Even towards Washington DC there is the potential for 1 to 3 inches of snow.

Other than a possible flurry south of NYC, Sunday will be mostly cloudy and dry for the area, with high temperatures in the upper 30s to lower 40s. Clearing skies are expected overnight but with much colder temperatures, similar to those of Friday night.


Next Week: Slowly Warming Up

As the storm exits the region, Monday will bring partly sunny skies to the area with a breezy NW wind expected. High temperatures will slightly warm up, peaking in the upper 30s to mid 40s across the area. Low temperatures on Monday night will be the warmest in days, likely staying above the 20 degree mark even in the interior parts of the area. Tuesday will bring temperatures above 40 degrees across the area, and may even get close to the 50 degree mark in the immediate NYC area which will be the warmest temperatures in the area since the most recent Tuesday two days ago but still below the average high temperatures for this time of the year. Temperatures will continue to rise afterwards ahead of a potentially more significant storm in the late week that may bring rain to the area, potentially bringing an end to this cold pattern. More information will be posted on the longer range as details become clearer.

Wednesday, March 23, 2011

Mar 23-24, 2011 Storm Updates

Below, storm updates will be posted on the major late season snowstorm currently affecting the area.

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8:35 PM: Storm Already Ending

After I made my previous update, the second round in Pennsylvania began sliding east southeast, and from the latest observations, it is clear that places north of the NJ/NY border and southern Connecticut will fail to see any significant precipitation tonight. The second round of the storm is currently affecting most of the area, bringing heavy sleet and thundersnow for northern New Jersey and even in NYC. Looking at the radar loop, however, the northern end of the precipitation in eastern PA is slowly shifting south, not moving east like originally expected.

The storm has already ended for northern Sussex county and most of Orange county for the main part, with some more snow showers expected but no additional moderate-heavy precipitation. Over the next 1-2 hours, precipitation will slowly begin to weaken north of I-80 in northern New Jersey while mixing with and changing over to snow, though additional moderate to heavy sleet will continue in NYC for at least the next 2-4 hours. Steady precipitation will also begin to end in southern Connecticut over the next hour or so.

This is the last update for tonight. The next full update will be posted tomorrow, discussing the unseasonably cold air expected to affect the area through the weekend and early next week and whether any additional snow may fall.


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6:30 PM: Second Round Approaches, But More Rain Than Snow?

The widespread severe thunderstorms in the Ohio Valley have recently moved into Pennsylvania, but are beginning to become less severe and more of a widespread area of heavy rain and thunder. Some thunder has even been observed west of NYC along with the sleet. This round of the storm is moving rather quickly and is well south of where it was modeled to be last night, with the northern edge expected to only reach southern New England. The problem, however, is that temperatures are marginal at best for the immediate NYC area, where rain and sleet is currently falling.


With the latest observations, it is clear that the area will see some sort of moderate-heavy precipitation out of this second round, but in what form it falls is the question. It appears at this time that temperatures may be warm enough that New York City and places south of Interstate 80 see mainly rain out of this second round, followed by back end snow/sleet with no accumulation in NYC and perhaps a little accumulation towards I-80 in New Jersey. Places towards southern Westchester, and eastern NE New Jersey should see more of a rain/snow/sleet mix changing over to snow at the end, with accumulations generally less than an inch, and places such as southern Connecticut, the rest of northern New Jersey and southeastern New York seeing mostly, if not plain snow with accumulations between 1 to as much as 4 inches expected.


The storm will be quick to move out, and is expected to begin ending after 12-2 AM from west to east. By the morning, other than a few snow showers, dry conditions are expected. Stay tuned for more updates this evening on the second round of this storm.


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3:25 PM: This morning, as the storm moved in, snow fell across the entire area, however a band of heavy snow unexpectedly set up from northern New Jersey into NYC, resulting in accumulations already as high as 5-8 inches in the higher elevations of northern New Jersey this morning! Snow continued to fall throughout today, and is currently mixing with sleet especially in the immediate NYC area and further south/east.


We are currently seeing a very interesting set up with the storm. While snow is falling in the New York City area, Chicago has been seeing plain rain, temperatures in southwestern Pennsylvania and central Ohio have even reached the 70 degree mark, and a major severe weather outbreak is currently ongoing in parts of the Ohio Valley. While with such a set up, it would be easy to think that the warmth will easily push into New York City with mild temperatures, the storm is blocked from going east and doing so, and will be forced to slide east southeast later tonight, keeping the area in the cold sector of the storm and keeping places north of NYC such as Rockland and northern Westchester counties with mostly snow.




Tonight's Forecast: Through the evening hours, occasional snow and sleet are expected to continue across the area with light accumulations possible inland and no accumulations in the immediate NYC area and further east. What happens overnight, however, is still slightly uncertain, with several possibilities for tonight's round. The thunderstorms currently in the Ohio Valley will eventually move east and affect the region, not with thunderstorms but with additional widespread precipitation, but the latest models are split on how this affects the area.


With the current observations, it is unlikely that this is a mainly rain storm for New York City and NE NJ, with the northern scenarios such as the NAM, RGEM and HRRR showing moderate to potentially heavy snow for tonight with as much as 2-5" for parts of the immediate NYC area and higher accumulations to the northwest of NYC, and the southern scenarios including the UKMET, RUC and ECMWF showing the storm mostly to the south of the area with barely additional 0.2" QPF falling in the form of snow, which would have difficulties accumulating.


At this time, I am expecting a mix to continue through this evening with snow becoming more widespread later tonight before ending, with little to no accumulations in NYC and up to 1-4 inches north and west of NYC possible, however this is still uncertain and is subject to changes. Updates later today will discuss this in more details.

Tuesday, March 22, 2011

Mar 22, 2011: Late Season Snowstorm Tomorrow

After a storm brought accumulating snowfall to the interior parts of the area yesterday, today brought a brief return to drier conditions with high temperatures peaking in the mid to upper 40s inland and in the upper 40s to lower 50s for the rest of the area with a maximum temperature of 53 degrees in Newark.

This return to dry conditions, however, is already ending as a storm is producing clouds in the area with temperatures and dew points dropping, resulting in snow tomorrow morning, and wintry precipitation will continue to affect the area until Thursday morning. This is not the last of winter, however, as a cold pattern continues through at least early April with two additional storms that may bring frozen precipitation to the region, potentially including parts of the area.



Tonight Into Thursday: Significant Late Season Snowstorm



The snowstorm that brought up to 3-4 inches for the interior parts of the area yesterday was significant for this time of the year, however this storm will be an even bigger snow producer. There continues to be uncertainty with the models, with the GFS still steady with a northern solution and the NAM steady with a colder and further south scenario, however despite the differences with these models, New York City is still expected to see snow tomorrow regardless of whether it accumulates or not, and the interior parts of the area may end up with 4 to as much as 7-8 inches of wet snow by Thursday morning.


Model Analysis: This winter, we have had many cases where 24 hours away from the storm there were still differences with the models, and this storm is yet another one of these cases. For the last few days, the GFS model has consistently been north of the other models, showing mostly rain for New York City and even showing plain rain for the interior parts of the area. The highlight runs today were the 12z and 18z NAM, which showed a significant snowstorm for the northern parts of the area. The 12z ECMWF is also colder than the GFS, and the GGEM is in between the NAM and GFS.

The NAM has not had a solid handle on this storm yet, and at this time I consider its earlier runs to be too far south, which kept New York City with mostly, if not plain snow. The GFS, at the same time, is north of every single model and even its own ensemble mean, and while I do not think that the storm would end up as far south as the NAM has it, I do think that the GFS may adjust slightly south tonight to result in a slightly colder scenario. Its 18z run did shift slightly south of its 12z run, however it remains to be seen whether it was just a temporary jump or if it is taking a southern trend. The latest run of the NAM has also trended north, showing a warmer solution for New York City with 6 hours of plain rain, which is still a little south of my thinking but it has trended north from its runs this morning.

At this time, I used a blend of the NAM/GFS, expecting the 850 mb line to end up near New York City/northeastern New Jersey, which would bring rain to these areas for a while in the evening and early overnight hours and keeping the storm as entirely frozen for the interior parts of the area, however it is possible that the storm ends up slightly colder of what I used for tonight's update. Stay tuned for updates tomorrow afternoon and evening that will discuss any potential changes for the remainder of the storm.


Storm Forecast:


Looking at the latest radar, precipitation is already moving into Pennsylvania. Most of this is virga, or precipitation that is not reaching the ground, however by at least 3-6 AM, precipitation is expected to begin reaching the ground west of NYC. Temperatures are currently dropping across the area with dew points also dropping, which will likely result in evaporative cooling once precipitation moves in, allowing the storm to begin as snow for most of the area. Due to mild surface temperatures, no accumulations are expected in NYC by tomorrow morning, however especially in the interior parts of the area, up to an inch of snow may be possible by tomorrow morning.


Tomorrow: As 850 mb temperatures remain below freezing, snow will continue north and west of NYC in the morning, however warmer surface temperatures will result in rain mixing with the snow by the morning into the early afternoon hours for Long Island, New York City and portions of northeastern New Jersey with the interior areas seeing plain snow. By the middle of the afternoon, however, the 850 mb line will begin to reach New York City, and a changeover to plain rain is expected for New York City by noon-2 PM, getting as far north as northeastern Bergen County and southern/central Westchester county. Parts of NW NJ should also change over to a period of plain rain, however for these areas, most of the storm will bring frozen precipitation.

Due to mixing and rain, no accumulations are expected during the day for Long Island and New York City with light accumulations less than 1 inch for southern/central Westchester and parts of northeastern New Jersey. For the interior parts of the area, a wet snow will fall for most of the day, mixing with sleet and rain late, with at least 1 to 3 inches of snow expected.


Tomorrow Night: As the low pressure moves off the coast near southern New Jersey, moderate precipitation will continue to affect the region, though with the 850 mb line still north of NYC, rain is expected to continue there as well as in NYC and northeastern New Jersey. The interior parts of the area will continue to see snow/sleet mixing with rain at times, eventually changing over to snow. By 2 AM, the storm is expected to begin moving out of the area, and by Thursday morning, a few snow showers are expected.


Forecast Snow Totals:


By the time that the storm ends, at least 3 to 7 inches of snow are expected for the interior parts of the area, with a trace to 1" for the immediate NYC area except for NYC itself, which should see little or no accumulations. The scenario I am going with would support a mainly rain storm for NYC other than non-accumulating snow falling in the morning, but even if this storm was to produce more snow, during the day the snow would barely stick with surface temperatures still above freezing, snowfall rates not heavy enough, and the sun angle also an issue. If the overnight event was to bring snow to NYC, there would likely be at least light accumulations, but places further inland would still see more significant accumulations.

For Bergen County and southern Westchester/Rockland counties, I am expecting up to 1-2 inches of snow, which will mainly accumulate with the front end of the storm tomorrow morning and towards the end of the storm tomorrow night. The interior parts of the area should see mainly snow, mixing with sleet and rain at times, though at least 3 to 7 inches are still expected, locally up to 8" in the higher elevations towards Orange County.

The map is a moderate confidence one, and areas of uncertainty include central Pennsylvania, where the accumulations may be shifted a bit south. Accumulations may also be needed to be revised in parts of the area north/west of NYC, but that will be discussed below. I also went with the northern solutions for accumulations in New England, and the northern end of the 4-8" zone may be shifted slightly south.


Other Scenario: For tonight's update, I sided with the northern model solutions. There continue to be colder models, however, and should this scenario verify, the interior parts of the area would see plain snow with 4 to 8 inches expected, places such as Bergen County and southern Rockland/Westchester would see 2 to 4 inches of wet snow mixing with sleet and potentially rain at times, and New York City would see a trace to 1-2 inches of snow with a brief period of rain in the evening, and otherwise a mix of rain, snow and sleet. At this time, the more likely solution is the one discussed previously, and the snowier solution is losing support. While I'd give a low probability for such a scenario happening, I will keep an eye on the observations tomorrow in case such a scenario becomes reality, which is unlikely but a possibility.


There is still some last minute uncertainty with the forecast, and it may not be completely nailed down until we reach the observation range while the storm is ongoing tomorrow. Stay tuned for storm updates that will be posted tomorrow in the afternoon and evening hours on this storm.


Longer Range: Either tomorrow's update or Friday's update will discuss in more details the coming storm potentials on Sunday and Tuesday/Wednesday and how they may affect the region.

Monday, March 21, 2011

Mar 21, 2011: More Snow On The Way

- The 5-Day Forecast was updated through Thursday. As stated below, it is possible that tomorrow's forecast may adjust to a slightly colder scenario depending on the observations, and a Snow Watch may be issued in parts of the area.

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During the last week of winter, the area observed unusually mild temperatures, reaching the 70s across most of the area, typical of early June. The beginning of spring, however, greeted the area with a late season snowfall, the first of several potentials. As expected, the storm brought snow north and west of NYC and even brought some flakes into New York City, but accumulations north and west of NYC exceeded the expectations, with as much as 3-4 inches of snow observed in northern NJ and southeastern New York!

Cloud cover is expected to clear tonight with low temperatures dropping into the upper 20s to upper 30s, with mild temperatures expected to return again tomorrow, bringing high temperatures into the upper 40s to mid 50s across the area, however this warmth will not last for long as a much colder pattern sets up, bringing a more January/February-like pattern for the first few weeks of spring.



Tuesday Night - Thursday: More Wintry Precipitation Expected



Today's storm in the Northeast was just a preview of what will come later this week. A storm that will affect the Midwest tomorrow with widespread heavy snowfall will move east southeast, bringing the moderate to heavy snow risk into the southern and potentially central Northeast. There is still a model spread with the storm, with some models showing a moderate snowstorm for NYC while other models show mostly rain, though at this time, I continue to lean with the warmer solutions.

The GFS remains the warmest model today, showing some snow for NYC on Wednesday morning followed by rain for most of the storm, with the snow risk well north/west of NYC. The 12z NAM run was the highlight of the day, bringing a significant snowstorm to the interior parts of the area with snowfall amounts likely exceeding 6 inches in that run, however at this time the 12z NAM is a wet and slow outlier.


Scenario #1 : For now, I went with a similar scenario to the one I have went with for the last several days but with some minor changes adjusting to a slightly colder scenario. The storm will begin early on Wednesday morning with precipitation moving in from west to east, and with cold temperatures, the storm should start out with snow especially west of NYC. By the late morning, a steadier snow will develop for the interior parts of the area, with the immediate NYC area mixing with rain by the early afternoon hours. Through the late evening hours, snow, sleet and potentially rain will continue inland with rain for NYC, mixing with snow further north/west, and as the storm begins to end overnight, precipitation type will change over to snow across most of the area.

Should this scenario verify, little to no accumulations are expected in NYC, however up to 1-2 inch of snow may be possible even in the immediate north/west suburbs of NYC, with the potential for 3 to as much as 6-8 inches of snow for the interior parts of the area, especially towards Orange County, NY. Rainfall amounts up to 1 inch may be possible in Long Island in this scenario.

Scenario #2: The other scenario would be a further south, drier and colder storm. Such a scenario would result in mostly snow for New York City and a mostly snow/plain snowstorm for northern New Jersey, with the potential for 3 to 8 inches of snow in N NJ and even light accumulations in NYC as the storm ends. At this time, this is not the most likely solution, however I will continue to watch this solution in case it becomes more likely. Even if this storm does end up as a snowstorm for New York City, accumulations would be very difficult, as during the day, temperatures would be above freezing, with the best risk for accumulations being overnight should the storm track far south enough to bring moderate snow into NYC, and even then, surface temperatures should be marginal, preventing significant accumulations in NYC itself.

I updated the 5-Day Forecast page tonight through Thursday, leaning towards the northern solution but going slightly colder, however it is possible that depending on tomorrow's observations, the forecast may have to be adjusted to a slightly colder and snowier scenario, which would be snow to rain/snow to snow in NYC and plain snow for the interior parts of the area. Due to uncertainty with the exact areas of moderate-heavy snowfall, I did not issue any alert yet, however this storm is expected to meet the requirement for a Snow Watch (3-7 inches of snow) where it produces moderate snow, and I may issue a Snow Watch tomorrow for parts of the area where the best risk of snowfall amounts exceeding 3 inches would end up. Stay tuned for more information on this storm.



Weekend And Beyond: Cold, Then More Snow?



Thursday's storm is not the only snow potential for the region with the developing pattern. Through at least early April, spring will be put on hold as a cold and potentially snowy pattern continues. For Thursday through Saturday, high temperatures are expected to be in the mid 30s to mid 40s across the area, and low temperatures will be in the 20s for the entire area including NYC, and will even reach the mid 10s for the interior parts of the area.

By Sunday, another storm will approach the region, and the latest models also indicate a snow potential out of this storm. Most models, including the GFS, ECMWF and GGEM, keep most of the snow to the south of the area, however we have also seen these models in their medium range show the snow staying south of the area with tomorrow's storm, with those areas now expected to see rain. At this time, I expect the storm to trend north on the models, but the question is how far north it will trend and whether there will be any changes with the expected set up. These details will be sorted out as the storm reaches the short-medium range, however at this time there is the potential for additional wintry precipitation out of this storm for parts of the region, potentially including the area. Stay tuned for more information on this storm and how it may affect the area.

Sunday, March 20, 2011

Mar 20, 2011: Snow, Sleet Tomorrow Morning

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

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Today brought mainly sunny skies to the area as a high pressure moved through the region, with temperatures similar to those of yesterday. Cloud cover is increasing as the next storm is moving in, but unlike most of this month's storms, however, this one will produce frozen precipitation north and west of NYC, with the potential for up to 1-2 inches of snow and sleet in Sussex and Orange counties by tomorrow morning. This is not the last of the snow possibilities, however, as yet another storm on Wednesday may bring frozen precipitation to parts of the area.


Tomorrow's Outlook: Snow, Sleet To Rain

The cold air mass that has been over the area for the last few days is now moving out as a storm affecting the Great Lakes is moving east, expected to move through the Northeast tomorrow and towards Maine tomorrow night. There will be enough cold air ahead of the storm to result in frozen precipitation especially north and west of NYC, and as a result, once precipitation moves in between 3 and 6 AM west of NYC, it will fall in the form of snow for northern NJ and interior SE NY. 850 mb temperatures will also be below freezing for NYC and Long Island when precipitation starts, however due to warm surface temperatures, rain is expected to fall in these areas.

A burst of moderate snow is possible in the northwestern parts of the area tomorrow morning, especially towards Sussex and Orange counties, which will then change over to sleet, followed by a changeover to rain. The storm will be quick to move out, ending west of NYC by noon-2 PM. By the time that the storm ends, at least 1 to 2 inches of snow and sleet are expected in parts of Sussex and Orange counties, and I issued a Light Snow Alert for these areas as a result.

For southern Connecticut, precipitation will begin in the morning hours and intensify by the early afternoon. Despite 850 mb temperatures below freezing when the heaviest precipitation falls, it will do so during the afternoon with warm surface temperatures, and precipitation type by then will most likely be rain. The storm will end by the late afternoon.


Wednesday - Thursday: Snow Or Rain?

Today's models continued to show a snowstorm potential for the area, with the biggest risk of such an event coming from the GGEM model, showing heavy snow for northern New Jersey, and the NAM model, which keeps most of the snow south of NYC but eventually brings moderate snow into parts of the area. The majority of the models, including the UKMET and the 12z ECMWF, also show a mainly snow event for the area, however the GFS remains with a northern solution, showing mostly rain for NYC. While I think that the GFS is having issues handling the storm, I continue to expect this storm to produce mainly rain for NYC.

The models have continued to trend north from yesterday, with the GGEM previously showing the heaviest snow south of northern NJ now showing the heaviest snow over NJ, the GFS which had a mainly rain for NYC trending even more north with today's runs, and the UKMET trended north as well. The only model that did not trend north was the ECMWF, which had rain for the area in its 00z run but trended south in its 12z run. The ensemble means of the GFS, GGEM and ECMWF are still north of their operational runs, and while I do not think that the storm tracks north of NYC, at the same time I do not think that it will track south of the Delmarva Peninsula.

The GFS continues to show a rain event for the area, however its last few runs have not been very consistent, with its 18z run showing a norlun trough for the Northeast which no other model shows. It is also drier than the other models. Regardless of whether it is correct or not with its rainy solution for the area, the GFS is most likely not done trending yet, and additional changes are likely with its solutions tomorrow.


Storm's impact in NYC Area: Overall, my thoughts have not changed since yesterday on how the storm affects the area, expecting the best risk of moderate snowfall in the area well north of NYC. The storm may start out on Wednesday morning with snow especially north and west of NYC with light accumulations possible, however the main part of the storm will likely be rain. Should this scenario verify, the rain in NYC would last until at least 2-4 AM on Wednesday night with amounts between 1/2 to as much as potentially 1 inch possible, and the rain may mix with and change over to snow in northern NJ as the storm ends.

The main model consensus still shows a mix/snow storm for the area, and even though I expect this consensus to shift north at this time, it is still a possibility that we see a further south and cold storm that would bring a moderate snowstorm to places such as northern New Jersey. At this time, such a scenario is unlikely, however it will be watched in case it becomes more likely. Stay tuned for more information on this storm.


Longer Range: Beyond this storm, a much colder air mass will result in below average temperatures for Friday and the weekend, with high temperatures struggling to reach the 40 degree mark in NYC and staying in the 30s inland, and low temperatures even dropping into the 10s for the interior parts of the area. The next storm is expected to affect the area around Monday, 3/28.

Mar 20, 2011 Morning Update


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

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A full update will be posted later tonight, however there are two updates with the latest expectations for this week, which will be discussed in more details tonight.


Tomorrow's Storm: Snow, Sleet To Start

Precipitation is expected to move in from west to east betwee 3 and 8 AM. With cold air initially in place, precipitation will begin as snow north and west of NYC as well as southern Connecticut, and even New York City may see a few flakes early in the storm. As warmer air moves in, precipitation will change over to sleet, then rain, ending between noon and 5 PM from west to east.

Little to no accumulations are expected in the immediate NYC area, however 1 to 3 inches of snow and sleet are expected towards Sussex and Orange counties, and a Light Snow Alert has been issued. This storm will be discussed in more details tonight.


Wednesday Night: Rain For NYC, Snow Further North

Today's models have continued the north trend that began with yesterday's morning models, with the GFS and ECMWF models now showing rain for NYC with a track slightly north of the one I used for last night's scenario map. The GGEM has a significant snowstorm for northern New Jersey, and the NAM/DGEX also show a southern solution, however I expect both the GGEM and NAM to trend north to show mostly rain for NYC. With tonight's update, I will explain in more details the two possibilities for this storm, the more likely one being rain with some snow for NYC and northern New Jersey with the best risk of a moderate snowstorm in interior southern Connecticut, and the less likely one being a light to moderate snow event for northern NJ and NYC.

Saturday, March 19, 2011

Mar 19, 2011: Spring Starts With 2 Snow Potentials

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

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Note: The 5-Day Forecast was not updated tonight, however it will likely be updated on Sunday morning. In addition, a Light Snow Alert will likely be issued for Sussex and Orange counties for accumulating snow and sleet on Monday morning.

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As a cold front moved through overnight, temperatures steadily dropped across the area, and today's temperatures were nowhere near as warm as yesterday's temperatures, staying steady in the mid 40s to lower 50s in the afternoon with the warmest temperatures of the day observed around midnight.

Spring officially starts tomorrow, however the pattern coming up suggests otherwise, with tomorrow starting a more winter-like pattern that may last through early April. Not only will this pattern bring colder than average temperatures, but for this coming week, we are looking at not one, but two storms that will bring snow to parts of the area.


Tomorrow's Outlook:

After cold temperatures tonight, which will drop into the upper 10s to upper 20s away from NYC, tomorrow will bring mild temperatures to the western parts of the area but chilly temperatures further east. With sunny skies and an ESE wind expected, high temperatures will peak in the lower to potentially mid 50s from NYC and further west, and in the mid to upper 40s for the eastern parts of the area except for the immediate coast which should stay in the lower to mid 40s.


Monday: Morning Snow, Sleet For Interior Areas

A storm expected to move through the Northeast on Monday will push the cold air mass out of the region, but not before bringing front end frozen precipitation for the Northeast and even into the area. The latest models continue to suggest that 850 and 925 mb temperatures will be below freezing as the storm moves in, allowing for the precipitation to begin as snow as far as the immediate north/west suburbs of NYC early on Monday morning, with a start of snow and sleet also likely in interior southern Connecticut. As temperatures steadily warm up throughout the late morning, precipitation will first change over to sleet, then rain, ending by the early afternoon hours from west to east.

No snow and sleet accumulations are expected in the immediate NYC area, as any snow that falls should be wet snow that melts on contact, however especially towards Sussex and Orange counties, more snow and sleet are expected, and there is the potential for 1 to 2 inches of wet snow and sleet to accumulate. A Light Snow Alert may be issued on Sunday morning for this storm.


Wednesday - Thursday: More Significant Snow Potential North Of NYC


Monday's storm is only the first of two snow risks for this coming week. As the storm moves into Maine, it will bring a colder air mass behind it, bringing colder temperatures for Tuesday night. A storm is expected to move near Chicago on Tuesday, bringing a wide area of moderate to potentially heavy snow for the central and northern Great Lakes area, and with a high pressure to the north supplying the storm with cold air, freezing rain is a risk for the southern Great Lakes.

The main highlight of today's models for the area are the ECMWF, which show heavy snow for northern New Jersey with significant accumulations, and the DGEX, which also shows heavy snow for northern New Jersey. The GFS is the warmest model, showing mostly rain for New York City with snow further north, and the GGEM is the coldest model, keeping the heaviest snow south of New York City. Based on this data, there would be support that the moderate snow axis could move through northern NJ and the immediate NYC area, however when looking at the overall trends, since this morning the models have adjusted northward. With the cold air mass in place and high pressure to the north of the storm, it will be blocked from tracking north of NYC and would likely take an ESE track, however especially with the ensemble means of the GFS, GGEM and ECMWF still showing northern solutions, I sided with the northern scenario at this time.

Should this scenario verify, the storm will track from Chicago towards southwestern Pennsylvania and move off the coast of southern New Jersey. The best risk of accumulating snow would be north of NYC, especially towards interior southern Connecticut and Orange County, NY, during Wednesday night. Some snow would likely fall in northern NJ and NYC, especially towards the end of the storm on Thursday morning, however the main precipitation type would be rain or a mix. The highest risk of moderate snow accumulations would extend from the central/northern Great Lakes into the southern/central Northeast.


As this is still in the medium range, there is still uncertainty with the storm. The other possibility is that a colder and further south storm may verify, bringing a moderate snow potential into northern New Jersey and potentially the immediate NYC area. At this time, this is not the most likely scenario, however it needs to be watched in case it does become the expectation. Stay tuned for more information on this storm and how it may affect the area.

Friday, March 18, 2011

Mar 18, 2011: From Summer To Winter

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

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As a storm in Canada pulled in a much warmer air mass with a southwest wind, the area got to see a preview of summer today as temperatures surged into the 70s across most of the area, ending up slightly warmer than expected. Most of the immediate NYC area saw mid 70s, and Newark even reached 80 degrees!

A cold front moving through tonight will bring the area back to spring-like weather, with temperatures expected to stay in the mid 40s to mid 50s this weekend with mainly sunny skies. The drop in temperatures will continue through next week, as after a brief warm up on Monday night following a light rain event, the area will return to winter-like conditions, with a cold spell expected by the late week and into the weekend, and a storm on Wednesday and Thursday might even bring snow to parts of the area.


Weekend Outlook:

After today's mild temperatures, tomorrow will be nowhere near as warm. High temperatures will return to more seasonable levels, peaking in the upper 40s to lower 50s across most of the area, with a few mid 50s near NYC and further southwest. Partly to mostly cloudy skies are expected early in the morning, however cloud cover will quickly clear up, with mostly sunny skies by the evening. A NNW wind is expected.

Saturday night is expected to bring much colder temperatures as a high pressure moves near the area. Clear skies are expected, with low temperatures dropping into the 20s for the entire area except for New York City, which should see lows in the lower 30s. The interior parts of the area may even reach the upper 10s. Sunday will be slightly cooler, with high temperatures generally expected to peak in the upper 40s to lower 50s with mainly sunny skies.


Monday - Tuesday: Light Rain, Briefly Warming Up

A storm is expected to move towards Maine on Monday night, which will push the cold air mass out of the region. Increasing cloud cover is expected on Sunday night, with occasional light rain on Monday. Precipitation will begin early on Monday morning, and it is possible that with cold temperatures initially in place, the storm may start out with snow and/or sleet in the western parts of the area. Temperatures will steadily rise throughout the day, eventually peaking in the early overnight hours in the mid 40s to lower 50s across the area. A brief break in the cloudy conditions is expected early on Tuesday along with high temperatures in the upper 40s to mid 50s across the area, with increasing cloud cover overnight.

By Wednesday, however, things become more uncertain. Today's models took a low pressure just south of Chicago on Tuesday ESE as it is blocked from moving due east, with the low pressure ending up east of the North Carolina/Virginia border by Thursday morning. Most of the models today, including the GFS, GGEM and ECMWF have shown snow for at least parts of the area, however as this is expected to be a weak storm, precipitation from this storm should generally be light. The GFS has adjusted north from last night's runs, however it may still be a little too far south, and I would not be surprised if it adjusts itself slightly further north with future runs.

Looking at the overall set up for the storm, it appears that the storm would likely move in an ESE direction, not due east, and it is unlikely to track north of the area, putting the area in the cold part of the storm. The exact details are still uncertain, which give a range of either no precipitation, a plain cold rain, rain switching over to light snow, or mostly light snow falling, with the storm reaching the coast either near the Virginia/North Carolina border or near southern Delaware, as the ensemble means of the GFS, GGEM and ECMWF show, however there is the potential for at least some light snow to fall out of this storm, with the best potential towards the interior parts of the area and during Wednesday night as the storm starts to end. As this is a weak storm and surface temperatures will not be much below freezing, if below freezing at all, if this storm brings snow to the area, any accumulations will be light.

It is not certain that it will snow, it is still possible that this will be plain rain or that the storm will miss the area to the south, however there is the potential for snow to fall in parts of the area. At this time, in the 5-Day Forecast, I went with mostly rain but mentioned the potential for snow to mix with the rain on Wednesday in the western parts of the area, however this is still a low confidence forecast and is subject to change. Stay tuned for more information on this storm and how it may affect the area.


Longer Range: After this storm moves out of the region, a colder air mass will move in. High temperatures will struggle to reach the 40 degree mark, and in the interior parts of the area may fail to reach 40 degrees, and overnight lows will be in the 20s, potentially upper 10s inland. The cold will begin to moderate by Sunday, however at this time it does not appear that any major warm up is expected any time soon.

Thursday, March 17, 2011

Mar 17, 2011: Winter To Return One More Time

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

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As a high pressure moved into the Southeast today, temperatures quickly warmed up, reaching the 60s across most of the area with mostly sunny skies. The mild temperatures won't last long as a cold front on Saturday night brings back colder temperatures, with temperatures on Sunday morning below freezing across most of the area. Temperatures are expected to warm up on Monday and Tuesday as a storm moves to the north of the area, however afterwards, winter is expected to make one last comeback as a much colder air mass moves into the region for the late week and the weekend, and even snow may return to parts of the region one last time this winter.


Tomorrow's Outlook:

As a storm moves near southeastern Canada towards Maine tomorrow, it will draw in additional warm air, bringing the warmest temperatures to the area since October. High temperatures are expected to peak in the upper 60s to lower 70s for NYC and further west, with mid to upper 60s for the eastern parts of the area except for the coast, which should see temperatures in the lower 60s. Parts of the immediate NYC area could even reach the mid 70s.

The day will start out mostly cloudy with a southwest wind, however partly sunny skies are expected by the afternoon with a breezy WSW wind becoming west. Winds may gust up to 30-35 mph, especially in the eastern parts of the area.


Weekend Outlook: Dry, Chilly

Tomorrow night, as the cold front comes through, temperatures will drop into the mid 30s to lower 40s across the area, with lower to mid 40s in NYC. A high pressure will move towards the area on Saturday, resulting in clearing skies other than a few possible morning showers, and high temperatures will rise into the mid 40s to lower 50s across the area with a few mid 50s in the immediate NYC area.

The high pressure will move over the region, resulting in mainly clear skies for Saturday night. Low temperatures will be cold, dropping into the lower to upper 20s away from NYC, and in the lower 30s for New York City. Sunday will bring temperatures similar to those of Saturday.


Tuesday - Thursday: Winter To Appear One Last Time?

Cloud cover will increase on Monday morning as a storm approaches the area from the west. This low pressure is expected to move through Maine on Monday night, bringing some rain to the area with mild overnight temperatures potentially rising into the lower 50s in the immediate NYC area, with drier conditions returning by Tuesday afternoon and high temperatures likely in the upper 40s to mid 50s.

The exact details are still uncertain, but looking at the overall model scenarios, there is a general consensus that there will be a strong high pressure in southern Canada moving southeast. The storm will likely intensify as it moves through Maine and towards southeastern Canada, helping to pull in the cold air towards the region. Then uncertainty comes into the forecast with a low pressure that is expected to be near Kansas on Tuesday.

To the left, I posted an image from the 18z GFS run which can be found in this link. The green and blue areas represent precipitation, with green representing light precipitation and blue representing moderate-heavy precipitation. The southernmost blue line represents 850 mb temperatures at zero degrees celsius, north of that line it would typically be cold enough to support snow. This image shows a low pressure in southern Virginia, with precipitation falling in the form of snow in Pennsylvania and central/southern New Jersey.

When looking at the models, it is important to keep in mind that this is still several days away, and considering the model performance this month, it is likely that we will see at least some changes with the set up, but with the majority of the models showing similar scenarios and this storm already entering the medium range, there is the potential for snow to fall somewhere in the region from this storm. It is still possible that the models change back to a no snow scenario, however today's models are suggesting that there is a potential for snow to fall somewhere in the region.

As should be expected in the longer range, the exact solutions are different with each model. The GFS suppresses this snow risk to the south of the area, with the 12z GGEM brought a moderate to heavy snowfall to parts of the area. There is a wide range of possibilities with this storm, with snow potentilly falling to the south of the area, over the area, just north of the area or no snow at all, but with the set up currently suggested, it is unlikely that it snows well north of the area. For now, the snow potential is still low, however if future model runs continue to show similar scenarios, there may be a higher risk for snow to fall somewhere in the region. Stay tuned for more information on this potential storm and whether it may bring snow to the area or not.


Longer Range: Regardless of whether it snows or not, it is expected to get cold again after this storm. The GFS is still likely overdoing the cold air with high temperatures below freezing, but there is the potential for high temperatures to end up in the mid 30s to mid 40s after this storm. More information will be posted on the longer range as details become clearer.

Wednesday, March 16, 2011

Mar 16, 2011: Warmth Returns For Now

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

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After a moderate rainstorm that brought anywhere from 1/4 to as much as 3/4 inch of rain this morning cleared the area, partly to mostly cloudy skies were observed as temperatures went up into the mid 50s for the western parts of the area, mid 50s to lower 60s for the immediate NYC area, and the lower 50s for the eastern parts of the area. Sky cover will continue to clear, with temperatures warming up additionally tomorrow and on Friday, reaching the lower 70s for parts of the area by Friday.

Cooler temperatures are expected to return by Saturday, with more rain expected to affect the area between Monday and Wednesday night of next week, however there are indications that there may be a cold spell to follow this storm, with below average temperatures a likely possibility by next weekend.


Tomorrow's Outlook:

Tomorrow will bring mostly sunny skies to the area as a high pressure moves towards the Southeastern US, resulting in a WSW wind. High temperatures will be warmer than today, peaking in the lower to upper 50s for the eastern parts of the area, and in the lower 60s from NYC and further west. A few mid 60s are possible southwest of NYC.



Friday - Sunday: Warm, Then Cooling Down

As a storm moves towards Maine on Friday, it will pull additional warm air into the region, resulting in even warmer temperatures. There is some slight uncertainty with exactly how warm it gets, which also depends on the cloud cover as mostly cloudy skies are expected in the morning, however the immediate NYC area is expected to reach the 70 degree mark. In the warmer case scenario, high temperatures may even get close to the mid 70s in Newark. The latest models, however, have been trending colder, with the latest NAM run only bringing high temperatures into the mid to upper 60s for NYC. For today's update, I went along with the warmer scenario, though it is a possibility that Friday's forecast highs may have to be slightly lowered with tomorrow's update. A breezy WSW wind is expected, with gusts up to 20-30 mph expected.

Overnight, the cold front will move through, bringing curolder overnight temperatures back into the upper 30s to mid 40s across the area, and some light rain is expected late overnight into Saturday morning. Saturday will bring colder temperatures, peaking in the upper 40s to mid 50s across the area.

Colder temperatures will briefly return on Saturday night as a high pressure moves into the area along with a cold air mass. Overnight low temperatures are expected to drop into the mid 20s to lower 30s away from New York City along with mostly clear skies, with Sunday's highs warming up into the upper 40s to lower 50s.


Next Week: More Rain, Then Cold?

As the high pressure exits the area, cloud cover will increase again on Sunday night as another storm moves in from the west. There is uncertainty with the exact details, however at least light to moderate rain is expected for Monday and Tuesday. On Wednesday, it appears that the main storm should begin to move through, however as usual, there is uncertainty with the exact track. The 12z GFS took this storm far south enough to bring a snowstorm to Washington DC and Baltimore, a solution which I am considering an outlier at this time. For now, I am going along with a track that would take the storm through the central Northeast, however this track is subject to changes as details become clearer.

This storm is expected to bring additional rainfall to the area, and if the track I am currently using verifies, mild temperatures will return, though they will not be anywhere near as warm as Friday is expected to be. There is consensus with the models for the storm to move out of the area on Thursday, but it appears that a cold spell may follow this storm.

A -NAO is expected to develop, and the GFS and ECMWF models have been consistently showing a cold air mass dropping into the region by Friday and Saturday of next week. While the GFS is likely overdoing the cold air, showing high temperatures below freezing for the area, I am thinking at this time that a cold spell is likely, which may bring below average temperatures. Stay tuned for more information on next week's storms and the potential cold spell that may follow.

Tuesday, March 15, 2011

Mar 15, 2011: Taste Of Spring On Friday

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

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After cold temperatures this morning, dropping as low as the lower 20s for the western parts of the area, temperatures warmed up into the upper 40s to lower 50s from NYC and further west, with lower to mid 40s east of New York City. The area is currently seeing cloudy skies as a storm is starting to move in, which will bring moderate to heavy rain but nowhere near as severe as the last two storms, clearing the area by tomorrow afternoon.

Temperatures will warm up significantly by the end of this week, even reaching the lower 70s in the immediate NYC area on Friday. This warmth will not be here to stay, however, as there are indications that a colder pattern may develop in the longer range.


Tomorrow's Outlook: More Rain

Light rain is currently moving into the western parts of the area, and is expected to continue spreading overnight into the rest of the area. By 2-5 AM, a widespread moderate rain is expected to affect most of the area. The rain will then become locally heavy at times tomorrow morning, especially near the immediate NYC area. The storm will be quick to exit, starting to end west of NYC by 10 AM, with most of the rain expected to have cleared the immediate NYC area by noon-2 PM.

By the time that the storm ends, rain totals between 1/2 and 3/4 inch are expected across the area, with the potential for amounts locally as high as 1 inch. While this storm's rain totals are nowhere near as high as the previous storms, there will still be enough rain to add to the ongoing flooding in the western parts of the area. This will be the last significant rain event for a while, however, as the next storm on Friday is expected to stay to the north of the area, which is discussed in more details below.

Temperatures tomorrow are expected to remain in the 40s to lower 50s until the storm ends, then will rise into the lower 50s for the eastern parts of the area, and in the mid to upper 50s for the western parts of the area. It is possible that places just southwest of NYC reach 60 degrees. East winds are expected in the morning, becoming west by the evening.


Thursday - Saturday: Warm

Once the storm exits, a much warmer air mass will move into the region, resulting in the warmest temperatures across the area since fall. Thursday will bring mostly sunny skies with high temperatures in the mid 50s to lower 60s in the eastern parts of the area, and in the lower to mid 60s for NYC and further west.

With Friday bringing a WSW wind and 850 mb temperatures near 10c, even warmer temperatures are expected. With a storm to the north of the area, partly cloudy skies are expected with temperatures reaching the 60s across the entire area. Temperatures for the western parts of the area are expected to reach the upper 60s, with lower 70s for most of the immediate NYC area. While unlikely at this time, there is even the potential for places just southwest of NYC to end up just under the 75 degree mark.

This warmth will only be short lasting. The storm to the north of the area will bring a cold front through, with high temperatures on Saturday only in the lower to mid 50s across the area. Dry conditions will last temporarily, with the next storm expected to bring rain to the area on Tuesday, March 22nd.


More information will be posted in the longer range as details become clearer, including the potential for a colder pattern to develop by the last week of March.

Monday, March 14, 2011

Mar 14, 2011: 70 Degrees Possible On Friday

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

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The area again observed mainly cloudy and chilly conditions today, with more cloud cover than originally anticipated, even bringing scattered rain and snow showers to parts of the area. High temperatures reached the lower 40s in the interior parts of the area and the mid 40s for the rest of the area.

These chilly conditions are only temporary, as mostly sunny skies are expected tomorrow along with high temperatures reaching the lower 50s for NYC and places further west. Moderate to heavy rain will return into the forecast for Wednesday, however the rain is not expected to be a long duration event, with rain totals between 1/2 and 3/4 inch expected. Temperatures will continue to warm for the rest of the week, reaching the 70 degree mark in New York City by Friday, which only becomes the average high temperature in early May.


Tomorrow's Outlook:

**Note: Temperatures in the western parts of the area may be a little cooler than the map to the left shows.**

After today's chilly and cloudy conditions, tomorrow will bring more sunshine to the area, with a sunny start to the day and increasing clouds by the late afternoon. Temperatures will be slightly warmer than today, but will not be very warm just yet. The high pressure just to the east of the area will result in a SSE wind, which will lead to colder temperatures in the eastern parts of the area, expected to reach the mid 40s. The warmest temperatures will be from NYC and further west, where high temperatures are expected to peak in the upper 40s to lower 50s.


Wednesday: Locally Heavy Rain Possible

After a break that lasted a few days since the last storm hit the area with heavy rain and significant flooding, yet another storm will affect the area on Wednesday, however this storm will have a much lighter impact when compared to the previous storms. Light rain is expected to develop during the early to mid overnight hours, which may mix with sleet and potentially snow for the interior parts of the area before changing over to rain. During Wednesday morning, the rain will intensify and may be locally heavy at times, however the storm will not last long, and by 2-3 PM the rain should already be east of New York City.

This storm will not have heavy rain totals associated with it, however rain totals of 1/2 to 3/4 inch are still expected across most of the area. This will be the last storm to affect the area with precipitation for a while, as other than the potential for a few showers on Friday night, the next storm to affect the area will be about a week afterwards, on Tuesday and Wednesday, March 22-23.


Thursday - Saturday: Early May-Like Temperatures

As mentioned with yesterday's update, warmer temperatures will return to the area behind this storm. On Thursday, mostly sunny skies are expected with high temperatures warming up into the upper 50s to lower 60s. A few mid 60s cannot be ruled out southwest of NYC. As a weak storm moves into the northern Northeast on Friday, a much warmer air mass will continue to move into the area, with high temperatures expected to peak in the mid to upper 60s for most of the area on Friday. Temperatures are expected to even reach the lower 70s for parts of the immediate NYC area, something New York City has not seen since the fall.

There has been a slight change in the expected storm scenario, and it appears that the storm will come in two parts for the Northeast, one on Friday and the other from Friday night into Saturday. Both of these rounds are expected to stay to the north of the area, and other than an isolated shower, mainly dry conditions are expected. Low temperatures will fail to drop significantly overnight, staying in the 50s overnight for the immediate NYC area, and will rise on Saturday into the lower 60s with breezy conditions expected.


Sunday And Beyond: More Warmth, For Now

A colder air mass will return into the region behind the storm, but it will fail to produce very cold temperatures, with high temperatures still expected to peak in the lower to mid 50s across the area on Sunday. Afterwards, there is uncertainty with the specific details, however another storm is expected to stay to the north and west of the area, bringing in warmer temperatures once again for next Tuesday and Wednesday as well as the next potential for a widespread rain event for the area. More information will be posted on this storm as details become clearer.