April 20, 2012: Heavy Rain, 3+ Inches Possible

Forecast Highlights:


- Warm Tomorrow, Thunderstorms Overnight
- Heavy rain for Sunday night, 2+ inches expected
- Seasonable temperatures return for next week


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As a cold front slowly approached the region with increasing clouds, a warm air mass continued to push in, resulting in another mild day for interior areas. Temperatures peaked in the lower to mid 70s inland, upper 60s to lower 70s in the immediate NYC area, and the mid to upper 60s in Long Island and southern CT. Another warm day is expected tomorrow away from the coast, although as the cold front reaches the area, unsettled weather will return, with the first significant rain event since early December expected.


Tomorrow's Outlook:


As the cold front continues to move closer, mostly cloudy to cloudy skies are expected tomorrow with south winds. The warmest temperatures are expected further north/west, with temperatures in northern NJ and SE NY peaking in the mid 70s to near 80 degrees. NYC will reach the lower to mid 70s, with mid 60s to lower 70s in Long Island and southern CT. Coastal areas will remain in the lower to mid 60s. Rain and thunderstorms, locally strong, are expected along the cold front in Pennsylvania during the evening, with these storms getting into northern NJ and SE NY by the evening and overnight hours but failing to get much east of NYC.


Sunday - Tuesday: Heavy Rain, Up To 3-4 Inches


The cold front is expected to stall to the east of NYC overnight and on Sunday with cooler highs, reaching the lower to mid 50s across the area. Meanwhile, a low pressure will intensify near the Southeast US as it moves north up the coast, reaching the region on Sunday night into Monday as it begins to turn north, then NNW cutting through New York state. This track, along with a lot of moisture associated with the storm, will result in significant rainfall for a large part of the region and even a significant snowstorm further west.

Storm Scenario: The low pressure is likely to end up near southeast VA/eastern NC on Sunday, slowing down a little as it moves north and intensifies, ending up near eastern NJ on Sunday night. A steady moderate to locally heavy rain will move up the coast, reaching NYC by the early afternoon hours, intensifying throughout the evening hours. The low pressure will continue to send heavy rain up the coast along New Jersey and into most of New England, with increasing winds across the region, especially in Long Island and New England. Temperatures will also rise east of the low pressure on Sunday night into Monday morning, with parts of New England rising late overnight into the lower 60s. Meanwhile, to the west of the low pressure, colder air will move in, resulting in precipitation changing over to a wintry mix for western PA, West Virginia, and western NY, followed by a changeover to moderate to heavy wet snow. At least moderate amounts of snow are expected in these areas, making this an unusual late April significant snowstorm for these areas. The low pressure will then move into New York state on Monday with weakening precipitation and increasing winds.


Forecast for NYC Area: Periods of moderate rain are expected to develop across the area around the early afternoon hours on Sunday, steadily intensifying throughout the afternoon and evening hours along with steadily intensifying winds, gusting up to 35-40 mph in the immediate NYC area and 40-50 mph in Long Island/southern CT. The heaviest rain is expected during the first half of the overnight hours, with lighter rain by Monday morning and isolated showers for the rest of the day. Temperatures will also rise late overnight as the low pressure moves through, reaching the upper 40s to lower 50s further west and the upper 50s to lower 60s further east. Overall, at least 1.5 to 3.5 inches of rain are expected, with amounts locally up to 4 inches possible. Stay tuned for more information on this storm.


Longer Range: The storm will slowly move out of the region, with partly cloudy skies and highs in the 50s on Tuesday. The rest of the week is likely to end up partly cloudy, with temperatures slightly warming up but still remaining near to below average, reaching the 60s for highs. Another light to moderate rain event may be possible towards the end of next week.