Another dynamic storm system will feature a very active period for weather through Wednesday.
Vertically stacked low pressure over the Great Lakes with triple point low pressure over northern Virginia has generated a wide swath of moderate to heavy rainfall from the Carolinas up through the Great Lakes and Ontario. In addition there are a number of lines of severe storms over North Carolina and Virginia (tornado watches included). Warm frontal boundary across southern New Jersey will lift north toward the south shore of SNE by tomorrow morning with increasing warm air advection aloft.
Through tonight: Low level dry air continues to remain entrenched across the region, and this has resulted in most of the initial few hours of precipitation to not reach the ground. Clouds and virga will continue through the evening hours. This is also contributing to notable evaporative cooling that has resulted in a number of reports of sleet as far south as northern New Jersey and Long Island. Here in Keene, it is quite possible that we begin as a mix of rain and sleet with even a few snowflakes in any heavier bands.
Strengthening low level jet from the southeast will transport copious amounts of moisture inland, with PWATs up to 1.0" in Keene and 1.3" over eastern areas. In addition, total totals will rise to near 50 in Keene, and low 50s south and east, which suggests thunder is possible. Most of the precipitation should be east of us by the afternoon and there could even be a few peaks of sunshine. Total rainfall will range from around an inch in Keene to likely 1.5" to 2.5" over eastern New England.
On Wednesday, mid level trough remains over the eastern Great Lakes with cyclonic flow across New England. This combined with available moisture will sustain clouds and scattered showers over the region. A pool of cold air aloft will induce decent levels of instability. Total totals reach the low 50's, so we could see some scattered thunderstorms. Considering the cold air aloft, cannot rule out some hail as well.
On Thursday, trough axis will be aligned over New England with maximum cold air advection. The column should be drying out, so we'll see some sun, but cannot rule out a scattered instability shower considering the continued cold air aloft. By Thursday night, trough gets shoved out as ridging is pushed east, and 850mb temperatures steadily climb.
Model guidance continues to enhance the warm up for Friday through the weekend. There remains a tight consensus for strong ridging developing over the eastern two thirds of the nation. This will contribute to 850mb temperatures jumping up 15C in 36 hours between Thursday and Friday night. On Friday, any locations in SNE that have not seen 70's let, will break that barrier. On Saturday, much of SNE could potentially break the 80 benchmark! Sunny skies will definitely be featured both days.
The forecast for Sunday becomes a little trickier as the ECM wants to swing a short wave to our north with associated cold front passing though during the day. The GFS holds off the frontal passage until Monday. Regardless, we'll probably see some more diurnal clouds on Sunday than Saturday as a result of increasing low level humidity (yes, more and more like summer). So this could pull highs down a notch or two. On Monday, clouds will have increased, suppressing high temperatures. Should the quicker ECM solution verify, cooler air advecting south will also temper highs. Whenever the front should cross, the possibility will exist for thunderstorms, some strong.
As strong ridging remains in control to our south, the front will stall in the northern Mid Atlantic region, and the ECM is showing it pushing back north on Tuesday or Wednesday, with another round of showers, and rising temperatures for the end of the week.
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