Sunday, December 12, 2010

Dec 12: Cold Returns, Storm Next Weekend?

Since late this morning, there has been a break in the precipitation, though as expected, a round of heavy rain developed for Long Island/S CT, with lighter rain for the western and central parts of the area as the cold front slowly moves east. The rain will end from west to east, starting around 11 PM to 12 AM further west and later in the overnight hours further east.

The storm pulled in unusually mild air, leading to high temperatures peaking as high as the mid to upper 50s in the immediate NYC area, however due to the position of the storm, when NYC was well into the 50s this afternoon, places such as Baltimore and Washington DC were only in the mid 40s.

With the cold front pushing east, the rain will end tonight with the potential of scattered rain/snow showers tomorrow, however much colder conditions will quickly return, and by Tuesday the area will be struggling into the 20s.


Tomorrow's Outlook:

Tomorrow will be a mostly cloudy day with scattered rain/snow showers as the cold front brings a much colder air mass through. While the actual high temperatures will be early in the overnight hours in most of the area, during the day itself high temperatures will be steady in the mid to upper 30s inland, upper 30s to lower 40s in the immediate NYC area, and in the lower to mid 40s in Long Island/S CT. Temperatures will start to drop by the late afternoon, with NYC dropping into the 30s by 5 PM.


Tuesday - Wednesday: Cold, Breezy

For Tuesday and Wednesday, the cold air mass will stay over the area, with much colder temperatures. Highs on Tuesday will fail to reach the 30 degree mark across most of the area, with highs in the upper 10s possible inland. Low temperatures won't be as cold due to cloud cover, but may reach the upper single digits to lower 10s inland on Tuesday night. Due to the breezy conditions, wind chills in the single digits are expected across the area on Tuesday morning, with sub-zero wind chills possible inland.

Wednesday will bring slightly warmer temperatures as the cold air mass starts to weaken a little, but high temperatures will still be cold, in the mid 20s inland, upper 20s to lower 30s in the immediate NYC area, and lower to potentially mid 30s in Long Island/S CT.


Longer Range: Snow Stays South Thursday, Another Storm Sunday?

For Thursday and Friday, a weak storm will pass to the south of the area, bringing light snow to the southern Mid Atlantic, in some ways like the December 4 clipper that was well to the south of the area, and high temperatures are expected to moderate, potentially reaching 40 degrees in NYC.

By Sunday, however, the ECMWF model has been consistently developing a strong coastal storm that ends up retrograding inland, with its latest run bringing potentially over a foot of snow to NYC. The GGEM model also shows the potential of a coastal storm but is inconsistent with the smaller details. The GFS model has nothing in this time frame, but it usually has low accuracy in its longer range, for example at one point it showed today's rain storm as a snowstorm for the central/northern Mid Atlantic. While more trending is expected with the models as they are in their longer range, this time frame needs to be kept an eye on for a potential storm that may affect the area. Stay tuned for more details on this time frame.

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