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.

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