Sept 6, 2012: Stormy Saturday, Then Cooler

Forecast Highlights:

– Thunderstorms, some severe, expected Sat-Sat night
– Much cooler temperatures expected for Sunday-Tuesday
– Another warmth surge late next week


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Wednesday, September 5

Detailed observations coming soon (updated 10/7/12)

Thursday, September 6

Detailed observations coming soon (updated 10/7/12)

Tonight – Saturday Night: Warm, Then Stormy

Following today’s cloudier than expected conditions which also resulted in temperatures busting on the low side, generally dry conditions are expected again on Friday along with partly cloudy skies. Temperatures will end up warmer than they did today, reaching the mid to upper 80s from NYC and further north/west and the low to mid 80s in most of Long Island and southern Connecticut. It is not out of the question that more cloud cover once again takes place and temperatures end up slightly lower than currently expected.

A strong cold front will move into the region on Saturday, with a relatively strong trough behind it. The cold front, which will also help to keep hurricane Leslie far away from the eastern US, is expected to move through late on Saturday night, with a strong line of heavy and strong/severe thunderstorms expected on Saturday evening and the first half of the overnight hours. This line will be capable of producing scattered to potentially widespread severe thunderstorms due to supportive instability along with favorable wind shear for severe weather. More information on Saturday evening and early night’s heavy rain and severe thunderstorms will be posted with Friday’s update.

Sunday – Next Week: Much Cooler, Then Warming Up

Behind the cold front, a large trough will move into the region, bringing a much cooler air mass behind it with 850mb temperatures dropping to at least 6 degrees Celsius. This will support the coolest temperatures since the spring, and the start of the transition to an autumn pattern. With a high pressure moving through the region, clearing skies are expected for Sunday with mainly sunny conditions for the first half of next week, while breezy NW winds are expected on Sunday. Highs on Sunday are expected to only reach the mid to upper 70s across most of the area with low 70s inland (interior north/west areas), with temperatures overnight dropping into the 50s for most places outside of NYC, with upper 40s possible inland and low 60s in NYC.

The coolest temperatures are expected for Monday and Tuesday with the coolest air mass overhead. High temperatures on both days are expected to reach the upper 60s to mid 70s across the area, with the coolest temperatures further inland and the warmest temperatures in the immediate NYC area. The coolest low temperatures are expected for Monday night with clear skies, light winds and chilly 850mb temps supporting widespread lows in the 40s over northern NJ, SE NY, southern Connecticut, and the typically cooler areas in central/eastern Long Island. Temperatures in the suburbs are likely to end up in the upper 40s to mid 50s, with mid to upper 50s possible in NYC. Temperatures are likely to drop into at least the low to mid 40s for interior areas.

Following the cool temperatures early in the week, the high pressure will slide south of the area with ridging building back into the region. As a result, temperatures will gradually warm up during the mid to late week along with dry conditions and mostly sunny skies, with highs likely reaching the lower to mid 80s across most of the area by the late week, possibly reaching the upper 80s in the immediate NYC area in the warmer case scenario. The longer range becomes more uncertain, although the possibility is there for another cool down towards the start of the following week. Stay tuned for more information on the cool early-mid week temperatures and the longer range outlook.

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