Saturday, November 27, 2010

Nov 27: Heavy Rain And Wind On Wednesday

Note: The 5-Day Forecast was updated for the entire area tonight.

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Today was a partly cloudy day across the area with chilly and breezy conditions, with high temperatures in the upper 30s to lower 40s inland and in the lower to mid 40s for the rest of the area. Temperatures this morning were cold, but not as cold as expected due to more cloud cover than expected, with NYC failing to drop below the freezing mark. Temperatures are currently dropping very slowly across the area, but with clear skies and a high pressure, temperatures tonight should be cold again, and will likely be colder than those of this morning.

Temperatures should start warming up by Monday, with a storm expected to bring widespread heavy rain, windy conditions and potentially thunderstorms on Wednesday, being why I have a Rain Watch, or a 30-70% chance of rainfall amounts near or over 1 inch in effect for the central and western parts of the area. Temperatures should cool down again behind this storm, with the pattern setting up for what could be an active period of time in the longer range.


Tomorrow's Outlook:

Tomorrow should be a mostly sunny day across the area with a light WNW to NW wind expected. High temperatures will be in the lower to mid 40s inland and in the mid to upper 40s for the rest of the area.

Looking across the rest of the region, high temperatures should be slightly warmer than those of today, in the 30s to lower 40s and some 20s in the higher elevations. The southern Mid Atlantic should be slightly cooler, with highs in Washington DC and Virginia in the upper 40s to lower 50s.


Monday: Warming Up

On Monday, a low pressure near the Midwest and an exiting trough in the region should lead to warmer temperatures in the area. High temperatures will peak in the mid to upper 40s inland and in the upper 40s to lower 50s in the immediate NYC area, however temperatures will only continue to get warmer from this point through Wednesday.


Tuesday - Wednesday: Storm Produces Heavy Rain, Wind

On Tuesday, a strong low pressure should be present near the Great Lakes, moving NNE and bringing a cold front through the Ohio Valley and the Southeast, slowly moving east. This front will be capable of producing heavy rainfall and potentially strong/severe thunderstorms. For the scenario map on Tuesday, please refer to the map posted on the November 25 update.

Overnight on Tuesday, the storm will approach the area, with a wave of low pressure forming along the boundary and enhancing the rainfall around Pennsylvania. Tuesday night will be mainly cloudy for the area with rising temperatures as a warm air mass moves into the area, and rain increasing in intensity by the morning.

As the warmest air mass will be over the area on Wednesday, with 850 mb temperatures above 10c, high temperatures will peak in the upper 50s inland, and in the lower 60s in the immediate NYC area. Heavy rain will fall, mainly in the second half of the day, along with windy conditions. Some thunderstorms are also possible on Wednesday. By the time that the rain ends on Wednesday night, rain totals could range from 1 to 3 inches of rain across the area. Stay tuned for more details on this storm.


Longer Range: Cold End To Week, Storm Potential To Follow

After this storm, a much colder air mass should move into the area for Thursday and Friday. While it is uncertain how cold it gets, it appears that the cold air mass could be locked up over the area until at least Saturday, which if this scenario verifies, temperatures could be even colder than today and tomorrow, with high temperatures in the mid 30s to lower 40s and low temperatures in the upper 10s to upper 20s possible. These numbers could change over the next few days, so stay tuned for more details.

Those who have been watching the long range GFS model have been seeing crazy solutions showing up on the model, with several consecutive large storms affecting the Northeast after December 4-6, with cold air trapped over the area. The GFS seems to be incorrectly handling the pattern, and will likely change over the next few days. The ECMWF is showing a low pressure moving west to east across the United States, with redevelopment off the coast and potential for frozen precipitation in the northern Mid Atlantic. The models are all over the place with this storm as they are having difficulty handling the pattern, though it is likely that a storm should be present in this time frame and could affect the area. Stay tuned for more details on this potential storm and how it may affect the area.

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