Today will feature the calm before a storm as high pressure slides offshore and low pressure gathers strength in the southern Appalachians.
Look for clear skies across the area today before high clouds start to filter in this evening. As winds flip around to the south, low clouds may move onshore a few hours early especially east of Brunswick, possibly bringing a few ocean-effect flurries. High temps will range from around 15 up north to around 30 along the immediate midcoast, though high temps there won’t occur until after dark.
Snow will break out overnight, and with cold air in place everyone will start off with at least a little bit of snow. That said, this storm will be tracking up the Hudson Valley which puts us on the mild side, especially aloft.
By sunrise tomorrow, it should be raining along the coast east of the turnpike if you’re south of Portland and south of route 1 if you’re farther up the coast. That means whatever slushy dusting or couple inches piled up in the wee hours of the morning will be promptly washed away. Moderate to heavy snow will be falling inland.
The core of the storm pushes through between 7AM and 1 PM tomorrow. The rain/snow line will push inland and slowly break into a snow/sleet line (quickly races up towards the mountains) and a rain/sleet line (gets stuck in the foothills). Closer to the coast, winds will pick up out of the southeast and are likely to become strong enough to warrant fairly serious power outage concerns. The Midcoast could gust up to 65mph with 55mph gusts more common farther southwest. Intense winds are also likely on the northwest slopes of the mountains where downsloping could also push gusts towards 50mph.
The storm’s first cold front pushes through midday, shutting off the steady/heavy precip. Behind it, cold air rushes in rapidly aloft but more slowly at the surface. That will set up some instability and allow for scattered showers to develop especially southeast of the mountains. These showers may contain graupel or small hail in addition to heavy rain and gusty winds. At the moment I don’t think updrafts get strong enough for lightning but a rumble can’t be totally ruled out. We’ll see what the data shows tomorrow morning.
As far as snowfall accumulations, mostly this isn’t one to write home about. The mountains should see a solid foot. If you’re planning to chase this one for skiing, Sugarloaf is the place to be as mixed precipitation will be briefest there. Snowfall amounts will taper quickly as you go southeast with most of whatever falls along the coast quickly getting washed away by the subsequent rain.
I’ll have another look at this storm in tomorrow morning’s update.