Tuesday, December 7, 2010

Dec 7: Big Storm On Sunday, Then More Cold

Note: The 5-Day Forecast page was updated for the immediate NYC and the interior areas up to Sunday. Tomorrow's update may be a brief one, with full updates resumed by Thursday.

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Today was another mostly cloudy, cold and breezy day for the area, though temperatures were slightly warmer than expected, generally in the lower 30s inland and mid 30s in the immediate NYC area. Temperatures are expected to get colder though by Thursday, when high temperatures in the interior are expected to be in the 20s, with lows in the 10s away from NYC. Temperatures will start to warm up by Friday, however a developing storm will bring an end to the dry conditions by Sunday and Monday.


Wednesday - Thursday Outlook:

Tomorrow will be a partly cloudy day with breezy conditions at times. High temperatures will be in the upper 20s to lower 30s inland, lower to mid 30s in the immediate NYC area, and in the mid 30s for Long Island/S CT.

As skies clear tomorrow night, and a colder air mass moves in with 850 mb temperatures near -16c, low temperatures are expected to be at their coldest point yet, dropping into the lower to mid 10s inland, mid to upper 10s in S CT, mid 10s to lower 20s north/west of NYC, upper 10s to lower 20s in Long Island, and mid 20s in NYC.

Thursday will be the coldest day of this time frame, with high temperatures in the upper 20s inland, upper 20s to mid 30s in the immediate NYC area, and lower to mid 30s in Long Island/S CT, with mostly sunny skies expected.

Friday-Saturday: Weak Clipper Potential

On Friday evening, a weak clipper well to the north of the area will help push out the cold air out of the region, but in the process of doing so it is capable of producing a few rain or snow showers north of NYC, with snow showers inland. Any precipitation that falls should be light, with little to no snow accumulations expected at this time where it does snow. On Saturday, as the clipper pushes the cold air mass out, high temperatures will warm up, reaching the upper 30s to mid 40s across the area, but a developing storm to the west will quickly bring an end to the mild temperatures.

While there is still uncertainty with the storm, as the models have not yet reached a consensus, the storm is expected to be a strong one, tracking west of the area, with mainly rain falling with the exception of a light wintry mix potential inland when the storm starts and some flurries across the area once the storm ends. I am leaning at this time towards a scenario where the storm track through the Ohio Valley and ends up moving through the Northeast west of NYC, which would bring a scenario like the one mentioned above, with the warmest temperatures reaching the lower 50s in NYC between Sunday and Monday as temperatures could rise overnight depending on the storm track. This is only my current understanding of the potential scenario, and may change, as the models could trend more west, bringing more warmth to the area, or could trend east, potentially bringing a better chance of at least some wintry precipitation along with the rain. Stay tuned for more details on this storm.

While there is uncertainty on the exact scenario, once the storm brings the cold front through, temperatures are likely to quickly drop as a much colder arctic air mass rushes in behind the storm. There is uncertainty on how cold it gets, but Tuesday is expected to be the coldest day, with widespread high temperatures in the 20s across the area possible. Low temperatures in the 10s are expected in at least parts of, if not most of the area, and if the colder solutions verify, low temperatures may even drop below 10 degrees inland, though this is still uncertain. Stay tuned for more information on this potential cold spell.

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