A frontal system will affect the area over the next 2 days, producing scattered showers today and more widespread showers/thunderstorms tomorrow, with temperatures remaining near to slightly below average. A stronger trough will enter behind the front, with cooler than average temperatures and sunshine returning for the Wednesday-Saturday time period before a gradual upward trend in temperatures begins.
A few parts of the short term forecast have been revised in the afternoon.
Today – Tuesday: Some Showers, Storms
As of this morning, a few scattered showers are affecting northern NJ with rain totals generally under 1/4 inch. Mostly cloudy skies are expected today with additional isolated showers/thunderstorms with highs reaching the upper 70s-low 80s inland and the low-mid 80s for the rest of the area. A strong shortwave will continue to dig into the Great Lakes with a pre-frontal trough approaching the region overnight, with rain and thunderstorms, locally heavy, developing and affecting locations from NYC and further north/west into Pennsylvania, NY and New England by the late overnight-early morning hours, with rain totals locally over 1/2 to 1 inch of rain. Overnight lows will remain mild, ranging from the low 60s inland to the low 70s in NYC.
As the surface front moves through, widespread showers and thunderstorms are expected to spread across the area by the mid-late morning, continuing through the late afternoon and possibly evening before moving offshore. With a more humid and moist air mass, storms will be capable of producing locally heavy rain, and some strong or low-end severe storms containing strong wind gusts and hail are possible with some instability and 0-6km shear of 35-40 knots overlapped with the areas of instability, although widespread cloud cover and unfavorable lapse rates should limit the severe weather potential. Due to the slightly fast timing of the front, the severe weather risk is likely to be focused to the south of the area, possibly extending into SE New England as well. Highs are expected to reach the upper 70s-low 80s across most of the area. Storms should move out by the evening, with at least 1/4 to 1/2 inch of rain expected for most of the area, locally higher up to/over 1 inch, with clearing skies overnight and lows falling into the mid-upper 50s away from NYC and the immediate coast.
Storm updates will be posted on Tuesday if necessary, both on the blog and on Twitter.
Wednesday – Next Weekend: Cooler Temperatures Return
A strong shortwave will move through the region on Tuesday night, with a cooler air mass moving into the region from southern Canada as 850mb temperatures fall to at least 8C. A broad surface high pressure will spread into the region behind the departing cold front, with sunny skies returning on Wednesday with a NW wind at 10-15 mph and high temperatures reaching the low-mid 70s inland and the mid-upper 70s for the rest of the area. Mainly clear skies are expected overnight with chilly temperatures, falling into the upper 40s-low 50s inland (interior NW NJ/SE NY), mid-upper 50s in the north/west suburbs of NYC, southern CT and Long Island away from the coast, and upper 50s-low 60s in NYC and the immediate coast. The high pressure will remain stationary over the region for Thursday and Friday, with light winds, mostly sunny skies, and highs reaching the mid-upper 70s inland and the upper 70s-low 80s for the rest of the area. Overnight lows will slightly warm up a few degrees, reaching the mid-upper 50s away from NYC and the immediate coast.
By next weekend, the trough will lift out of the Northeast region, with rising heights aloft as ridging in the Atlantic slowly pushes west towards the region, keeping the mean trough over the central US as opposed to the eastern US. Meanwhile, the high pressure will continue to slide east, with the stalled frontal boundary slowly lifting north towards the region. Showers are likely at this time to spread back into Virginia by Saturday and Sunday, although there remains uncertainty regarding whether these showers reach the area or remain suppressed to the south/east; at this time, the latter scenario is favored, although the potential for some showers especially towards Sunday-Monday cannot be ruled out. A gradual upward trend in temperatures is likely, with highs returning into the upper 70s-low 80s for the weekend and likely the low-mid 80s for next week, with some models signaling the potential for above average temperatures. Stay tuned for more information on the longer range outlook.
Saturday, August 10 Observations:
The cold front that produced heavy rain and thunder on Friday moved through the area overnight, with more sunshine and a drier and much less humid air mass returning for Saturday. Temperatures did not cool down much, however, as temperatures aloft remained warm, with high temperatures reaching the low to mid 80s across the area. The highest temperature was 85 degrees tied in multiple locations, and the lowest high was 80 degrees in White Plains, NY.