Nov 15, 2010: Rain, Thunderstorms Tomorrow Night

– A Wind Alert is in effect for the area for Wednesday. Please check the “Weather Alerts” page for more information.

– The 5-Day Forecast was updated for the area tonight except Long Island/S CT. For more information on the forecast for Long Island/S CT, read the discussion below.

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Today was a mostly cloudy day across the area, with high temperatures in the lower to mid 50s for Long Island/S CT, in the mid 50s inland, and the mid to upper 50s for the immediate NYC area. There is already rain affecting the Mid Atlantic, which may reach the area later tonight, however this is not the main storm yet, as the low pressure that will become a large storm producing heavy rain and thunderstorms for the region will form tonight in the interior Southeast.

After a windy Wednesday, colder temperatures will return to the area with drier conditions, however there are signs that the pattern could be turning stormier and colder by Thanksgiving.

Tomorrow’s Outlook:

Tomorrow will be a cloudy day across the area with an ESE wind expected. High temperatures will be in the lower to mid 50s inland and in Long Island, with mid to upper 50s for the rest of the area. Lower 60s are possible south and SW of NYC.

Looking at the rest of the region, a storm entering the Ohio Valley will bring moderate to locally heavy rain in the western parts of the region, with light rain starting to fall in the area after 2 PM, however until the overnight hours, any rain that does fall in the area will be light, as the heaviest rain will fall to the west of the area.

Tuesday Night – Wednesday: Rain, Thunderstorms, Then Wind

Tuesday Night: The slight eastward trend I thought could happen yesterday did not happen, however that did not lead to major changes in the forecast, and the NAM model did trend west towards the other models as expected. The storm is expected to intensity on Tuesday night while slowly moving Northeast, being just west of Buffalo, NY by Wednesday morning. The storm, meanwhile, will bring a cold front through the eastern Mid Atlantic, including the area, which will bring a line of rain and thunderstorms.

For the area, Tuesday night is expected to start mainly dry, but especially after 12 AM, the storm’s cold front is expected to move through the area, which will lead to heavier rain, with some thunder also expected, with the heaviest rain from NYC and further north/northwest. By sunrise on Wednesday morning, the rain should start to weaken. Due to the area also being in the warm sector, temperatures will steadily rise overnight, with the actual highs being overnight, not in the middle of the day like they would typically be. Temperatures are expected to peak early on Wednesday in the mid to upper 50s inland, upper 50s to lower 60s in the immediate NYC area, and in the mid to upper 50s in Long Island/S CT.

Wednesday: As the storm will enter far southern Canada, cold air is expected to enter the storm and lead to snow in the northwestern side of the storm, however it will be too late for anyone in the US affected by this storm to get much more than a few flakes. As the heavy rain moves into the Northeast, the area will become drier with rain ending by noon, however as the storm exits, windy conditions will develop, leading to a mostly cloudy and windy late afternoon/evening on Wednesday, with winds potentially gusting above 40 mph. As such, I have issued a Wind Alert for the area. Windy conditions will continue into early Wednesday night, and calm down by Thursday morning.

Thursday – Friday: Cooler

On Thursday, mostly cloudy skies are expected for the area as scattered rain/snow showers fall across the Northeast, with high temperatures in the lower to upper 50s across the area. The whole cold spell for this time frame appears to be slightly warmer than expected yesterday, so I adjusted the temperatures for Thursday/Friday slightly higher than yesterday’s update. Please check the 5-Day Forecast for the latest expected temperatures for the area.

Longer Range: Quiet At First, Stormy, Then Colder By Thanksgiving
Today’s models continued to show with consistency a low pressure moving into northern Maine on Saturday, bringing a cold light to moderate snow in that area, which pushes out the trough. This will then bring even colder temperatures for the central/northern Northeast, with lows in parts of Maine dropping into the 10s overnight, but the cold air mass won’t be strong enough to push far south, and will create a boundary near the area where cold temperatures will take place further north, with comfortable to mild temperatures in the Mid Atlantic. This will continue into Monday.

By Monday night or Tuesday, a low pressure well northwest of the area is expected to push out the cold air mass, with a high pressure building in the Southeast leading to a Southeast ridge, where the eastern US is warm, while cold air starts to enter into the NW and north central US due to a strong negative PNA. The NAO is still negative, which prevents the ridge from getting too strong, as if the NAO was positive, we could’ve been seeing well above average temperatures in this time frame.

Afterwards, there is still uncertainty with the forecast as this is in the longer range, but there is the potential of a storm to affect the area around the 24/25th. Due to the southeast ridge and entering cold air to the northwest of the storm, if there is a storm, its track would likely be inland, and afterwards, colder temperatures could return for Thanksgiving weekend according to the models and the expected pattern. Stay tuned for more details on this time frame.

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