The first round of showers associated with this system has moved into New England and will continue through the day Wednesday. Scattered showers will continue to move through New England throughout the daylight hours. This comes as the system's warm front lifts through New England.
As the storm passes to New England's north, it will drag a powerful cold front across New England this evening. This cold front will produce a round of more widespread rain showers, gusty winds and a flash freeze throughout Wednesday night.
Hourly forecast (HRRR) from 6pm Wednesday to 5am Thursday:
RAINFALL/FLOODING
A majority of New England will see a half an inch to an inch and a half of rain through Thursday morning. Most of this will fall as the cold front passes through this evening. Downeast Maine will likely be the jackpot zone for New England, seeing upwards of 2+ inches of rainfall.
Flooding concerns are contained to the mountains and eastern Maine. Heavy rainfall will combine with 1-3 inches worth of snowmelt, which will likely cause some minor river rises. The mainstream rivers should remain fairly contained, but smaller creeks and streams will have an elevated risk to rise. There is also the potential for ice jam flooding as river ice begins to decay and shift.
Areas of Downeast Maine that don't have a snowpack will see 1.5-3 inches of rain fall on a frozen ground. Without snow to absorb this, there is an elevated chance for excessive runoff and poor drainage flooding.
In addition to the shield of steadier rain, a fine line of convection will likely develop along the front. This will produce locally heavy downpours, strong wind gusts and potentially a few thunderstorms. A couple isolated storms could even turn strong to severe across western New England. The Storm Prediction Center has much of Vermont and western Massachusetts in the "marginal" category (level 1 of 5) for thunderstorms to produce locally damaging winds.
WIND
Winds will pick up across New England this evening, with widespread gusts of 40-50mph just about everywhere. Most of the high wind watches and warnings from yesterday have been replaced with wind advisories as widespread gusts to 50mph are expected, not 60mph. High wind warnings do remain in effect for Cape Cod and Downeast Maine, where gusts to 60mph remain possible.
This could create scattered power outages across the region, but large-scale, widespread outages remain unlikely. Locally stronger gusts are possible as the convective line of showers moves through the area this evening and overnight, but 40-50mph gusts will continue throughout the day on Thursday.
FLASH FREEZE/SNOW
A rapid temperature drop will follow the cold front's wake. Despite strong winds that would normally help dry things out before freezing, temperatures are set to drop so quickly that a flash freeze is looking increasingly likely. Any wet surfaces/standing water will freeze quickly overnight. This will create very slippery surfaces Thursday morning.
Temperatures will drop 30-40+° in the span of 12 hours, from Wednesday evening to Thursday morning. Many areas will be approaching record highs in the 50s today, with temperatures dropping to the teens and 20s overnight.
On top of the overall drop in temperature, drops of 10-15° in an hour will be possible in some areas of the Green and White Mountains with drops of 10-20° in the span of a few hours across the rest of New England. With winds continuing to whip after the frontal passage, the drop in feels-like temperature will be even greater. Some areas may see a drop in wind chill value close to 50°.
With such a rapid drop in temperature will come the chance for the rain to briefly flip over to snow before precipitation shuts down amid drier air behind the front. Any snowfall would be limited, but an inch or two is possible across the northern tier of Vermont and New Hampshire. A quick dusting to an inch will be possible elsewhere.
Probability of snow accumulating at least 2 inches by Thursday morning:
Thursday will be New England's one cold day. After that, above average temperatures return for the weekend and into next week to kick off meteorological spring.