Jan 5, 2011: Tracking Two Snowstorm Potentials

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

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Notes:

- NYC Area Weather issued a Light Snow Alert and a Snow Watch for the area, please refer to the "Weather Alerts" page for the latest alert in your area.

- The poll for Friday's storm will end tomorrow evening, please vote if you have not done so yet. The current majority is for the solution where heavy snow affects NYC, with 8 out of 16 votes.

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Today was a partly sunny day across the area, with high temperatures close to the forecast but slightly warmer in some spots, in the upper 30s to lower 40s across the area. Temperatures will continue to slightly cool down over the next few days until Friday, when a storm staying to the south of the area will bring an inverted trough that may potentially affect parts of the area with locally heavy snow. This is not the only storm potential in the coming week, however, as there is also the possibility of yet another snowstorm to affect the region around the middle of next week.


Tomorrow's Outlook:

Tomorrow will be a mostly cloudy to cloudy day across the area, as clouds spread from the west due to a storm that will affect the area on Friday. High temperatures will be in the lower to mid 30s inland, likely towards the higher end of that range with a few upper 30s possible in the warmer case scenario, and in the mid to upper 30s for the rest of the area. As with today, a few lower 40s cannot be ruled out. A light WSW wind is expected.



Friday - Saturday: Uncertainty With Heavy Snow Band

As mentioned yesterday, the models showed the coastal low well to the east of the area, with an inverted trough being the snow producer for the area. Today's models have remained consisent with this solution, and this is the expectation for this storm. With every model showing at least some snow for the area, and the set up supporting this, it is no longer a question of if snow falls, but rather how much snow falls. With such a set up, however, it is difficult to locate the exact places that will be affected by the inverted trough, which will likely feature a heavy snow band stalling over some places, though there is the potential for this to happen in the central and eastern parts of the area.

This morning's models suggested this could be over New York City and NE NJ, with the NAM and GFS showing as much as a foot of snow, however have since trended northeast to focus the inverted trough over central/western Long Island, south central and southwestern CT, and southeastern New York. Due to the large spread, I put at this time a Snow Watch for the central and most of the eastern parts of the area for the potential of 2-5 inches of snow, locally as high as 10-14 inches, with a light snow alert for the western parts of the area, however this is subject to change.


Forecast for the NYC area: On Friday morning, light snow should spread across the area from west to east. At least a period of moderate snow is likely across the area as snow intensifies by the afternoon hours, however accumulations through then should be light, with up to 2 inches by the mid afternoon hours. By the evening hours, however, uncertainty comes in as the inverted trough appears to stall somewhere. The latest expectation for this is to happen somewhere around central/western Long Island, SW Connecticut, potentially extreme northern New Jersey, and southeastern New York, but it could shift around further east or west. Where the inverted trough stalls, heavy snow will develop and stay stationary, with amounts locally reaching or even possibly exceeding 10-14 inches in the places hit the hardest by the inverted trough. That area will be narrow, however, and most areas will just see light to moderate snow with perhaps an additional 1-3 inches at most. The snow will then become lighter in the late overnight hours and end by Saturday morning.

The snow will start out first with temperatures near freezing, leading to more of a wet snow with snow to liquid ratios less than 10:1, but as temperatures drop by the evening, the area should change over to a colder, high ratio snowfall, which will help lead to the high snow totals where the inverted trough sets up.


This is a complicated set up, and it may come down to tomorrow or perhaps even the morning of the day of the storm when we know for sure where the inverted trough sets up, as the models are having difficulties handling this feature. While for most, this will only be a light to moderate snow event with a general 1 to 3 inches of snow, isolated areas could end up with as much as near or even over foot of snow, potentially in the central or eastern parts of the area. Stay tuned for more information on this storm tomorrow along with a snow map.


Longer Range: Cold, Then Another Storm Potential

Colder temperatures will return on Saturday, with high temperatures only in the mid 20s to lower 30s across the area. While temperatures will start a slow warming trend by Sunday, they will remain below average, only in the upper 20s to mid 30s. By Monday, high temperatures will reach the lower to potentially upper 30s, however another storm could bring an end to the quiet conditions.

By now, it is certain that we will be seeing some type of storm in the East Coast around this time frame, but the latest models have trended much more southeast, now keeping the snow south of the area. While it is too early to nail down the exact track, the inland track is becoming less likely, and it appears that we may be dealing with the same question for this storm that we have had with most of the storms over the last month: whether the storm affects the area with snow or stays out to sea. An inland track cannot be ruled out, but it's not a very likely option at this time. Some models are showing potential for this to be a big snow maker either near or south of the area, and while these details will change around over the next few days, a storm is expected to affect the East Coast during this time frame, and may affect the NYC area between Tuesday and Wednesday. Stay tuned for more information on this storm and how it may affect the area.


The latest models continue to show the potential for a major arctic cold outbreak across the north central and eastern United States around the third week of January along with the potential for a storm sometime between January 16 and 20, and while these potentials are still too far out in the long range to be discussed in more details, I will continue to watch these potentials and will discuss them in more information once details become clearer.

Jan 4, 2011: Update On Fri-Sat Snow Potential

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

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With a weak low pressure to the north of the area today, the area experienced partly to mostly cloudy skies today, with high temperatures in the upper 30s to lower 40s across the area. Temperatures will slowly cool down over the next few days, however should cool down even more around the Friday-Saturday time frame, when a storm will affect the area with widespread light to moderate snow and the potential for a heavy snow band.


Tomorrow's Outlook:

Tomorrow will be a partly cloudy day across the area with a WNW wind expected. High temperatures will be slightly cooler than those of today but still not very cold, in the mid to upper 30s inland and in the upper 30s for the rest of the area. A few lower 40s cannot be ruled out for the immediate NYC area.

Thursday will bring similar temperatures for the area, if not slightly cooler, however cloud cover will be increasing ahead of the next storm that will affect the area with snow.


Friday - Saturday: Uncertainty With Heavy Snow Zone

Since yesterday, the models have trended well east with the storm that yesterday was modeled to be close enough to directly affect the area on some models, and there is more support for an eastern solution, however if this latest solution verifies, the area will still get affected by this storm, as it appears that an inverted trough may set up, extending snowfall northwest of the storm in the form of a line of heavy snow that sets up over a specific area, potentially bringing snowfall amounts as high as 6-10 inches to places affected by this band, but the question at this time seems to be where the band sets up.

Looking at the overall scenario, a weak low pressure should move out of the Great Lakes, bringing widespread snow showers to the region, with more moderate snow developing by Friday, bringing widespread light to moderate snow for the area, being why I raised the snow chance to 70% in the 5-Day Forecast. Light accumulations are possible on Friday, but should stay below 2 inches.

On Friday night is when the inverted trough comes into the picture. As it appears that the main storm could stay well to our southeast while starting to rapidly intensify well away from the coast, an inverted trough appears to form, but the question is where does it form. It appears that this could set up somewhere between NYC to northeastern Massachusetts, and where it does form, a narrow band of moderate to heavy snow will likely be stuck over that area, with heavy snow amounts while areas not too far away see light snow.


The models usually have difficulty locating exactly where this sets up, though at this time, I am going with a light snow event with up to 1-2 inches for most of the area, with the potential for as much as 6-10 inches in the central or eastern parts of the area, depending on where the inverted trough sets up. This is a difficult storm to forecast, and it may come down to the day or two before the storm when we get a better idea on where the snow band sets up. The possibility that the coastal low may trend closer to the coast to directly affect the area will also be watched, as a few models such as the NOGAPS are suggesting this possibility. Light snow alerts could be issued tomorrow for the area, with snow watches possible depending on where the inverted trough sets up. Stay tuned for more details on this storm over the next few days.


Longer Range: Cold, Then Potential Storm For Jan 11-13

On Saturday, when some snow is possible in the morning especially in the eastern parts of the area, high temperatures will be colder, with the latest models suggesting highs in the mid 20s inland and in the upper 20s to lower 30s for the rest of the area. At this time, I went slightly warmer than these numbers, though it is possible that the forecast highs may be adjusted slightly lower or higher.

Afterwards, the cold will moderate for early to mid next week. It appears that there may be another storm that could affect the area around the January 11-13 time frame, but there is a lot of uncertainty at this time, with solutions ranging from a storm well to the west of the area, to a storm bringing heavy snow to the NYC area, to a storm staying offshore. Unlike the previous storms, however, an inland storm track is a possibility that could be more likely than in the previous storms we've seen. Stay tuned for more details on this storm and how it could affect the area.

Jan 3, 2011: Cold And Stormy Pattern Developing

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

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Notes:

- The 5-Day Forecast was updated for the interior and the immediate NYC area tonight.
- The poll for the most extreme weather event of 2010 remains open until Wednesday. Please vote in the poll if you have not done so yet.
- Another poll has been opened for the potential impacts of the Friday-Sunday storm. Please vote your thoughts in the poll, which will close on Thursday.

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With the passage of the cold front last night, a cold air mass returned to the area today, giving the area a sneak peek of what is to come later this month. High temperatures were generally in the mid 30s across the area, with some upper 30s in the immediate NYC area. Dry conditions will continue until Friday, when a storm is expected to bring the potential of a snowstorm to the area, however this will start what will likely be an active middle of January.


Tomorrow's Outlook:

Tomorrow will be a mostly cloudy day across the area, with a southwest wind expected. High temperatures will be warmer than today, in the upper 30s inland with a few lower 40s possible, and in the upper 30s to lower 40s across the rest of the area, perhaps leaning closer to the mid 40s in the warmer parts of the immediate NYC area.

These warmer temperatures will be due to a weak low pressure near the Great Lakes, which may lead to an isolated flurry in the northern parts of the area but keep the better chance of snow showers well to the north and northeast of the area.


Wednesday - Thursday: Dry, Slightly Colder Than Average

On Wednesday, as the weak low pressure exits the region, a colder air mass will return once again with 850 mb temperatures slightly below -10c, however the surface temperatures may not be as cold, with high temperatures in the lower to upper 30s across the area. Thursday will bring similar temperatures, but with increasing cloud cover as a low pressure from the Great Lakes approaches that for the several days afterwards will bring widespread light snow to the region and the potential for a heavy snow event in New England.


Friday - Saturday: Watching Snowstorm Potential

Today's models continued the uncertainty from yesterday about this storm and how it develops, however there were some models showing a significant storm today, including the UKMET, the 00z ECMWF run which brought a huge snowstorm to the area even though it is likely an outlier in terms of how it handled the storm, and the GFS which showed a significant snowstorm for New England with smaller amounts for eastern Long Island/SE CT and barely any snow in NYC.

At this time, it appears that we will likely see a primary low pressure in the Great Lakes with the storm redeveloping off the coast and intensifying, potentially retrograding northwest towards the coast. Where the storm redevelops, intensifies, and where it moves from there are the main questions at this time, and could put the range of possibilities from a widespread heavy snow event from the NYC area further northeast into New England, to a storm which mainly affects New England with light snow for NYC, to a storm that stays mainly offshore with some moderate snow closer to the coast. At this time, however, the best chance for a significant storm still appears to be in New England.

At this time, I went with a 50% chance of light snow in the 5-day forecast, with potential mixing with rain near the coast due to above freezing surface temperatures in the beginning of the storm, but it may not be until Wednesday or Thursday when we see the models start to agree on a solution, so at this time the forecast has a slightly lower confidence level, and is subject to change. Stay tuned for more information on this storm and how it may affect the area.


Longer Range: Cold, Then Another Storm?

Once the storm exits, cold conditions will stay in the area, with high temperatures still in the 20s for parts of the area, moderating by the start of next week. However, it appears that there may be another storm threat for the January 12-14 time frame. The ECMWF has been showing a significant snowstorm for 2 consecutive runs for the area with the 18z GFS also showing a large storm, and while it is too early to look at the smaller details such as the exact storm track and precipitation types, there is the potential for a storm to affect the area during this time frame. More information will be posted on this over the next few days.

Updated Winter 2010-2011 Outlook

So far this winter, we saw a moderate to strong La Nina, which on average produces cold and snow from the NW US through the Great Lakes with a mild East. When making the winter outlooks in the fall, it appeared that this winter would at least start out differently, with an east based La Nina and a -NAO/-AO pattern persisting and leading to a colder than average East, which a moderate to strong La Nina would usually have a positive NAO/AO. That was true of December, however the pattern was much more extreme than previously thought, with the AO and NAO being very negative, locking in a very cold and dry pattern across most of the eastern and southern United States. The blizzard that the area saw last weekend shows the fact that only one storm can change the entire snow outlook, as with that single storm, parts of the area are already very close to their total winter average snowfall, with a few locations even passing their average snowfall. With the area already seeing these totals with another 2-3 months of winter left, upward adjustments are necessary for this winter's snow forecast.


January Outlook: Cold And Potentially Snowy Pattern

When making the final winter outlook, it appeared that the colder than average pattern may persist into early-mid January, with a mild pattern becoming established around mid January with the storm track going near the Great Lakes, bringing above average snow to these areas. The pattern, however, does not support this happening, as after a brief time frame which we are currently seeing, where the pattern is reloading and temperatures are warmer than average, starting on January 3rd the cold pattern will return again for the area, with the NAO and AO remaining negative through most of January, ending what was a brief and weak January thaw.

As a result, we are looking at a cold pattern for most of January, with the coldest departures in the Southeast and the Mid Atlantic regions. While January will start out dry, as other than a storm threat around January 7-9, it appears that a stormy pattern may develop after January 10, which combined with the cold may lead to several snowstorms over the Mid Atlantic and Northeast regions, including a potential storm between January 12-14. Depending on what happens in this time frame with the potential storms, it is possible that the NYC area may end up with above average snowfall for the month.

Around the third week of January, after 1/15, the AO is modeled to become strongly negative, and the GFS model has been consistent in showing some type of an extreme arctic air mass in this time frame with the ECMWF also starting to show this potential. Given the pattern, it is a possibility that we may see an arctic outbreak focus on the north central US and potentially affect the rest of the Northeast/Mid Atlantic around the third week of January, with the potential for the coldest temperatures of the winter to take place if this potential verifies. More detailed updates will be posted on this potential once it gets into the medium range, if there is still a potential.


February And March: Potential Break From Consistent Cold, Then More Cold And Snow?

By the end of January, there is more uncertainty with the long range forecast, however it is a possibility that the cold may weaken, with a milder pattern for parts of February with more cold and snow towards the Great Lakes region, though if we do see such a pattern evolve, at this time it appears to be unlikely to be as strong or as long as the final winter outlook had it, even though warmer temperatures than those of January are possible. It is possible that by late February and March, we could see a colder pattern returning with more snow threats into the Northeast, however the February and March outlooks are still uncertain, and more on these two months will be posted once we get towards the end of January.


Winter Oultook Update Summary:

Overall, with the changes in the forecast for January, including a potentially weaker warm up for February than originally expected, I am going at this time with below average temperatures in January and slightly above/above average snowfall, and if the snowy January potential verifies, the total winter snowfall may end up between 40 and 55 inches of snow for New York City, making this winter's snowfall above average, something which is quite unusual for a moderate-strong La Nina. Depending on how cold January is and the pattern that we see in February, the December-February time frame may end up with below average temperatures for the NYC area.

Jan 2, 2011: Cold Pattern Becomes Established

Today was a cloudy day across the area with scattered showers this morning due to a cold front moving through. A wave of low pressure brought a round of light to moderate rain to the central and eastern parts of the area this evening, which is now starting to end in the eastern parts of the area. High temperatures peaked in the upper 40s to lower 50s across the area, and with a cold air mass moving into the area and becoming established for most of this month, it will not get this warm again for a while.


Tomorrow's Outlook:

Tomorrow will be a mostly sunny day across the area with colder temperatures as 850 mb temperatures drop to near -10c. High temperatures will be in the upper 20s to lower 30s inland and in the lower to mid 30s for the rest of the area. A few mid 30s cannot be ruled out in the western parts of the area. A west northwest wind is expected.




Tuesday - Wednesday: Chilly, Dry

On Tuesday, as a weak low pressure moves through the Great Lakes, temperatures will briefly warm up, reaching the upper 30s to lower 40s across most of the area as the 850 mb temperatures slightly warm up before cooling down again as the low pressure exits the region and another cold air mass moves in. This low pressure will bring scattered snow showers to the Northeast, and while a few isolated rain or snow showers are possible in the area, the best chance for that will be to the north and east of the area.

For Wednesday, as previously mentioned a cold air mass will return with 850 mb temps dropping slightly below -10c, leading to high temperatures similar to, if not slightly cooler than those of tomorrow.


Thursday - Saturday: Potential Snowstorm Update

On Thursday, cloud cover is expected to increase in the area as a low pressure from the Great Lakes starts to approach the area, bringing scattered snow showers by Thursday night to the area. There is still uncertainty with the storm as each model does something different, however the models have nailed down a general track area and some potentials scenarios.

The low pressure will originally start out near the Great Lakes and will move east or ESE from there, and will bring widespread light precipitation, meaning that regardless of what the storm does once it exits off the coast, most of the region as well as the NYC area are likely to see at least some snow during this time frame, even if it's just flurries. There is uncertainty afterwards, however, with what the storm does once it moves off the coast, as intensification is expected to take place but the question seems to be when and where, and with the models still showing different solutions for this time frame, it may not be until at least Tuesday when we get a better idea of the likely scenario for this time frame.

At this time, it is possible that the storm simply moves out to sea and produces a little heavier snow for New England just as much as it's possible that the storm quickly intensifies and slows down closer to the coast with heavier snowfall from the NYC area further north/east lasting through Saturday and early Sunday. Despite this range, however, most models do agree that New England has the best chance of seeing a potentially significant snowstorm, the southern Mid Atlantic is the least likely place to see heavier snowfall, and that this storm will likely be nowhere near the magnitude of last weekend's blizzard for the area. In addition, windy conditions are possible once the storm moves away from the area. Stay tuned for more information on this storm and how it may affect the area.


Longer Range: Cold Pattern Continues

Regardless of what the storm does, it will get cold behind it, with the coldest temperatures so far this January. The latest models show high temperatures in the 20s for at least parts of the area for Sunday, which is reasonable at this time. Temperatures will moderate a little afterwards, however I am keeping an eye on the longer range with what could be a much stronger arctic air blast around the third week of January. More details on that potential will be posted with tomorrow's winter outlook update and also once we get closer to that time range.

Jan 2, 2011 Noon: Light Rain Approaching

3:40 PM: A weak wave of low pressure developing along the cold front that was first mentioned several days ago has developed, several hours earlier than expected. For the last two days, the models had this wave brushing the eastern parts of the area late this evening with light rain/snow, however with the wave already forming it is expected to finish affecting the area by this evening.

Over the next few hours, expect light to moderate rain to affect the central and eastern parts of the area, with the heaviest rainfall in the eastern parts of the area where up to 0.25-0.35 inch of rain is possible. Most places west and northwest of NYC will stay dry. The rain will end by the late evening hours, with the wave moving northeast to bring rain, mixing with snow inland to southeastern New England with snow for southeastern Maine.


Another update on this wave may be posted if necessary, otherwise the next update will be posted late tonight about the potential snow storm around January 7-8 and the cold that will follow.

Jan 1, 2011: Mild Temperatures To End Tomorrow

The 5-Day Forecast was updated for the interior parts of the area and the immediate NYC area, with the forecast for Long Island/southern Connecticut to be updated late tomorrow morning.

In addition, either tomorrow or Monday, an update to the winter outlook will be posted, with revisions to the original forecast, especially for January.

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As the warmest of the mild spell took place today, temperatures were even warmer than expected, surging into the lower to mid 50s across most of the area. The NAM and GFS models significantly underestimated the warmth due to the snow pack, and even the GGEM model, which was much warmer than the NAM and GFS, still underestimated the warm up, showing high temperatures only in the upper 40s.

Temperatures tonight will remain steady, if not slightly rise in some places, and will peak tomorrow in the mid to upper 40s with a few 50 degree readings possible. A cold air mass will then take hold, as a cold pattern becomes established for a good part of January.


Tomorrow's Outlook:

After some scattered showers tonight, which will be light with rainfall amounts up to 0.1 inch, potentially up to 0.2 inch in the wetter scenario, tomorrow will be drier but with mainly cloudy skies and an isolated shower possible. Temperatures will peak early in the day in the mid to upper 40s with a few 50 degree readings possible before starting to drop in the afternoon hours. A west wind is expected.


Monday - Thursday: Chilly And Dry

On Monday, a cold air mass will return with 850 mb temperatures near -10c, with high temperatures expected to be in the upper 20s to mid 30s across the area. On Tuesday, the cold air mass will slightly weaken as a low pressure moves east through the Great Lakes, bringing high temperatures in the mid 30s to lower 40s across the area. An isolated rain or snow shower is possible in the northern parts of the area, but the best chance for that will be to the north and east of the area, with otherwise mostly cloudy skies expected.

Colder temperatures will return by Wednesday and Thursday, with high temperatures expected to be in the upper 20s to mid 30s again, slightly warmer on Wednesday and slightly colder on Thursday, however cloud cover will start to increase due to a storm which despite a lot of uncertainty, appears that it may bring at least some snow to the area.


Friday - Saturday: Potential Snow Storm?

Over the last few days, I mentioned the potential for a storm to affect the area in the January 7-9 time frame. The models are now consistent with showing a storm, but each one develops it in a different way. The highlight of today's model runs was the 12z GFS which showed yet another 12+ inch blizzard for parts of the area, with the ECMWF keeping most of the snow to the north of the area. As this is in the longer range, it is too early to take each individual solution more seriously until we reach at least the medium range when the list of scenarios should start to be narrowed down.

While there is uncertainty with the exact scenario, we are likely looking at a weak low pressure that originates near the Great Lakes moving east, and from there it appears that intensification may take place off the coast, but where and when that happens is uncertain. At this time, it appears that the best chance for a significant snowstorm may be to the north and northeast of the area, however that is still uncertain and is subject to change. Stay tuned for more information over the next few days on this storm and how it may affect the area.


Regardless of what the storm does, however, it appears that there will be an arctic air mass behind the storm, and in the days after the storm, temperatures will be below average, with high temperatures potentially returning into the 20s for parts of, if not most of the area according to the latest models.