Sept 9, 2011: Mostly Dry Weekend Ahead

With Lee’s remnants out of the picture, today was a much nicer day across the area, with partly sunny skies and temperatures slightly warmer than expected, surging into the lower to mid 80s inland, mid to upper 80s in the immediate NYC area, and the lower to mid 80s across most of Long Island and southern Connecticut. These temperatures are warmer than the average for early September. Other than Sunday, which should be colder due to an onshore wind, warmer than average temperatures will continue through the middle of next week, with a risk of isolated showers lasting through Monday. By the middle of next week, a strong cold front will approach, bringing a risk of strong thunderstorms followed by the first significant cool spell of this fall.

Weekend Outlook:

Tomorrow is expected to bring partly to mostly cloudy skies across the area with the risk of an isolated shower or thunderstorm. Temperatures will be slightly cooler than those of today, reaching the upper 70s to lower 80s inland, lower to mid 80s in the immediate NYC area, and the upper 70s to lower 80s in Long Island and southern Connecticut.

On Sunday, an ESE wind is expected to develop, which combined with mostly cloudy skies and the risk of scattered showers, will bring colder temperatures. High temperatures are expected to end up in the lower to mid 70s inland, mid 70s in the immediate NYC area, and the lower to mid 70s in Long Island/S CT.

Next Week: Warm/Dry Start, Stormy/Chilly Ending

Drier conditions will return into the area early next week, with mostly to partly sunny skies expected for Monday and Tuesday. A warmer air mass will begin to move in from the west, bringing warmer temperatures, reaching the upper 70s to lower 80s from NYC and further west. Temperatures may potentially reach the mid 80s on Tuesday in the warmer case scenario.

The break from the rain will end on Wednesday as a strong cold front will move into the region. This front will also be responsible for pushing Maria out to sea and east of the Northeast U.S. This front is expected to bring thunderstorms on Wednesday into Wednesday night, which according to some models, could potentially be strong. The cold front will then move through the area, and a strong trough will come in behind the front, bringing the first significant cool spell this fall for Friday into the weekend.

There is still some model uncertainty regarding this cool spell, as some models bring unseasonably cold temperatures, especially the GFS, with lows reaching the 30s in the interior parts of the area and high temperatures only in the 50s to 60 degrees. Other models, such as the ECMWF and GGEM, show more reasonable temperatures, slightly warmer than the GFS, and a few models significantly weaken the cold air mass by the time that it reaches the region. At this time, based on the average temperatures for September, temperatures observed with past September cool spells, and the latest model runs, I am expecting temperatures to end up below average but not as cold as some models show, with highs potentially in the lower to upper 60s across the area and low temperatures in the 40s away from NYC. Parts of the interior Northeast could potentially see the first frost of this fall should this scenario verify. Stay tuned for more information on this potential cool spell.

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