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.

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