Sept 17, 2012: Stormy Tuesday, Then Cooler

Forecast Highlights:

- Rain, thunderstorms return on Tuesday into Weds morning
- Strong winds expected on Tuesday afternoon, night
- Cooler temperatures briefly return late this week

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Today - Tuesday Night: Dry, Then Stormy

Mostly to partly sunny skies will continue today, with increasing clouds overnight as showers and thunderstorms spread in from the southwest as a strong cold front approaches. Two rounds of thunderstorms are expected; the first will be in the morning to early afternoon hours, likely starting around 5-7 AM and lasting through at least 12-2 PM, when heavy thunderstorms are likely, possibly strong. The main risk with these thunderstorms will be strong wind gusts, and an isolated tornado potential cannot be ruled out. A brief break in the storms, especially east of NYC, is expected around the mid to late afternoon hours, although scattered strong thunderstorms are still possible, especially north/west of NYC. During the afternoon and late afternoon hours, winds will increase with gusts in the 40-50 mph range expected, likely exceeding 50 mph towards eastern areas.

The line now appears to come through earlier than originally expected, likely moving in after 9-11 PM into NYC. Some thunderstorms along the line will be severe, with strong wind gusts the main risk from the line. Heavy rain is also expected with localized flash flooding possible north/west of NYC. The storms will continue to move east through the area overnight, with drier conditions by Wednesday morning.


Wednesday - Beyond: Cooling Down

Highs on Wednesday will reach the upper 60s to lower 70s across the area with clearing skies, with overnight lows dropping into the low to mid 40s inland, upper 40s to mid 50s for the north/west suburbs of NYC and southern CT, and the mid to upper 50s in NYC. The cold front will fail to progress much east of the region, and as a result, temperatures will fail to significantly cool down. Thursday's temperatures will be similar to those of Wednesday, with slightly warmer lows on Thursday night. Widespread highs in the low to mid 70s will return by Friday.

The next cold front will likely move through around late Saturday into Sunday as another strong trough drops into the north central US. Not much precipitation is expected with this trough as less moisture from the Gulf of Mexico is expected compared to tomorrow's cold front, with cooler temperatures returning behind the front. The surge of cooler temperatures is also expected to remain transient, quickly moving out afterwards, but with ridging in Canada further east than the current observations, this cool period late next weekend into early next week may result in colder temperatures compared to those expected for later this week.