Mar 4, 2012 Morning: Warmth Returns Late This Week

Forecast Highlights:


- Chilly, dry conditions last through Tuesday
- Warmth returns this week, up to 65 degrees Thursday
- Rain returns Friday, drier and colder weekend


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During Friday, a widespread damaging severe weather outbreak affected parts of the Southeast and the Ohio Valley, with nearly 100 tornadoes observed that day. There were two main areas of thunderstorms, one in the Ohio Valley, and the other in the Southeast. The area of storms in the Ohio Valley moved into the area on Friday night into Saturday morning, bringing occasional showers, locally heavy, with generally up to 1/2 inch of rain across the area, followed by some clearing in the cloud cover and temperatures rising into the mid to upper 50s from NYC and further west and the lower 50s in Long Island/southern CT. The second area of storms in the Southeast, however, moved east and stalled just off the Southeast coast, where last night it developed into a colder coastal low pressure which is currently just to the east of the area, as shown in the radar to the left.

This coastal low will remain just east of the area through the entire day, with occasional showers expected in Long Island. Colder temperatures will return tomorrow and Tuesday as yet another snowstorm stays away from the area, this time affecting southern Virginia, before temperatures begin to rise by the second half of the week, easily passing 60 degrees on Thursday. This surge of warmth, however, will not last long, as a cold front will move through on Friday with colder temperatures returning by next weekend.


Today's Outlook:


Today (Sunday) will be another mainly cloudy day across the area, with some breaks in the cloud cover especially in the second half of the day from NYC and further west. Occasional showers are expected in Long Island and southeastern Connecticut, but no steady moderate rain is expected. High temperatures will be the warmest in the immediate NYC area, with highs in the mid 40s. Temperatures in NW NJ/SE NY will be in the lower to possibly mid 40s, with similar temperatures expected in Long Island/southern CT.


Monday - Tuesday: Colder, Still Dry


With the coastal low moving out, cloud cover will clear by tomorrow with a colder air mass moving in. Temperatures will end up colder than average, reaching the mid to upper 30s inland and the upper 30s to lower 40s across the rest of the area. The colder air mass, however, will also suppress an approaching clipper, which will once again stay well to the south of the area, instead resulting in a snowstorm for southern and central Virginia with a couple of inches of snow.

The coldest temperatures are expected on Monday night, with mostly clear skies and a high pressure allowing for radiational cooling to take place. Low temperatures in the lower to mid 10s are expected in NW NJ/SE NY, mid 10s to lower 20s in the north/west suburbs of NYC, and in the mid to upper 10s in southern CT and Long Island. NYC will be slightly warmer but still cold, with lows in the lower to mid 20s. Tuesday will be chilly again with mostly sunny skies and highs in the upper 30s to lower 40s across the area.


Wednesday - Friday: Quickly Warming Up


With the trough moving out, a ridge will develop in the eastern US, with a high pressure to the south of the area resulting in SSW/SW winds, allowing for a warmer air mass to move into the region. As a result, temperatures will quickly warm up by the second half of the week. Mainly sunny skies will continue through Wednesday with highs reaching the mid to upper 50s across the area, possibly getting close to 60 degrees near NYC. The warmest temperatures are currently expected on Thursday, with partly sunny skies and highs reaching the lower to mid 60s across most of the area. In the warmer case scenario, temperatures may pass 65 degrees in the immediate NYC area.


There is some uncertainty with the timing of an approaching cold front, which some models bring on Thursday and others on Friday. The main area of uncertainty is with a potential cutoff low, which the models are having a lot of difficulty handling, especially the GFS which stalls the cutoff in the southern US before taking it due north into the northern US. For now, I am leaning towards a solution slightly slower than the GFS and expecting the cold front to move through sometime around Friday, with showers possible and temperatures reaching the upper 50s to lower 60s, although the timing is still subject to change. Should the cold front be delayed into Friday night, temperatures on Friday would once again reach the mid 60s in parts of the area. Despite the uncertainty with the cutoff low, which complicates the forecast beyond next weekend, colder temperatures are likely to return behind the cold front for next weekend, with drier conditions likely but still not certain due to uncertainty with the cutoff. Stay tuned for more information on the late week outlook.