After analyzing the medium/long range forecasts (and double checking the calendar), I can finally say with confidence that today, May 9th, will be winter’s last hurrah here in Maine.
A coastal storm is currently bringing bands of snow to the area as it moves through the Gulf of Maine. After beginning as rain in some areas, snow is now being reported all the way to the coast. We have a few more hours of steady snow left to go before the storm moves east later this morning. During these next few hours, expect accumulations to range from absolutely nothing along the coast to a dusting on cold surfaces just away from the coast to as much as an inch in the foothills to 1-3″ in the mountains. Any discussion of accumulations is merely of interest to climatological record-keeping (and perhaps photography opportunities) and will have no impacts on road conditions or power lines (except maybe for northern Franklin and Somerset counties, or at elevations above 2,000 feet).
Steady snow will depart most of the area by around noon, potentially after changing back to rain along the immediate coast. As the storm intensifies in the Bay of Fundy during this time, expect northwest winds to begin picking up. Gusty winds will stay with us for the rest of the day as high pressure approaches from the west. These winds will be the most impactful weather observed today, as they are likely to gust over 50 mph across most of the region and as a result, are likely to result in power outages (especially where some snow has been able to accumulate on trees).
Along with the NW winds will come the opportunity for some sunny breaks downwind of the mountains. This sunshine will provide a (very) modest boost in temps near the surface. This slightly-less-cold air near the surface will then become unstable as record-breaking cold air moves in aloft. The net result will be the development of shallow convection across southern and western parts of the region later this afternoon. This convection will drop heavy snow, graupel, and possibly some small hail as it moves through during the late afternoon hours.
Here’s a nice loop of forecast model imagery showing steady precip this morning transitioning to squally precip this afternoon/evening. Squalls will settle down around sunset as daytime heating (what little of it we get today) fades.
High temps today will be near record lows thanks to the cold airmass moving in aloft and abundant cloud cover. Look for temps this afternoon to range from 30 in the mountains to 40 along the coast.