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.

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.

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.

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.

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.