A brief yet significant heat surge affected the region yesterday, with temperatures climbing into the low-mid 90s and heat index values into the 100s. While temperatures will cool down today, another relatively hot and humid day is expected away from the coast, with a cold front bringing a line of rain and thunderstorms for the evening. A much stronger cool air mass will return behind the front, with below average temperatures persisting through the middle of next week.
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Wednesday, September 11 Observations:
An unseasonably warm and humid air mass spread into the area, with 850mb temperatures near 20C and mostly sunny skies leading to July-like heat across the area, with highs peaking in the low to mid 90s away from the coast, with highs in the mid-upper 80s in SE CT and western Long Island and the low-mid 80s in eastern Long Island. Along with dew points in the mid 70s, peaking as high as 77 degrees in Montgomery, NY, heat index values reached the 100-106 degree range across most of the area away from the coast. The highest temperature was 97 degrees in Teterboro, NJ, and the coolest high temperature was 80 degrees in Montauk, NY.
Records set/tied on Wednesday, September 11:
Bridgeport, CT – high temperature
90 degrees (tied record: 90 degrees – 1983)
Islip, NY – high temperature
88 degrees (tied record: 88 degrees – 1989)
Today – Friday: Storms, Then Cooling Down
Yesterday’s hot and humid air mass moderated, with slightly lower dew points and temperatures aloft cooling down to at least 18C, which along with increased cloud cover and some storm coverage will lead to slightly cooler temperatures than yesterday, peaking in the mid to upper 80s away from the coast, where highs in the low to mid 80s are expected. Latest observations from the Weather Prediction Center (WPC) show several cold fronts in the Ohio Valley and Michigan regions, with the most notable front moving through the area late this evening. With moderately favorable instability and bulk shear parameters, a line of heavy rain and strong to locally severe thunderstorms is expected to develop in New York and Pennsylvania states this afternoon, then gradually track east; scattered storms are possible north and west of NYC in the afternoon hours, which could be capable of heavy rainfall and strong wind gusts, with the line of storms reaching the area towards the evening hours, likely weakening as it passes east of NYC but still capable of producing moderate to locally heavy rainfall.
Behind this front, temperatures will cool down overnight into the 60s across the area with decreasing humidity, with partly sunny skies, a breezy NW wind at 10-15 mph, and highs reaching the low 70s inland and the low to mid 70s for the rest of the area. The strong trough will enter the region overnight with 850mb temperatures falling to nearly 4C, but with the high pressure staying to the west keeping some cloud cover in place, along with the pressure gradient behind the departing cold front keeping a breezy northwest wind, overnight lows are likely to struggle falling below the upper 40s to low 50s away from NYC and the coast.