Tonight is the proverbial calm before the storm. Clear skies and light winds will allow temperatures to drop quickly via radiational cooling for at least the first part of the night, then as clouds increase from southwest to northeast, temperatures will become more steady as the night goes on.
Tomorrow is the first day of spring, but the weather really won’t resemble spring, as spring will arrive with a snowstorm. Snow should develop during the morning rush hour in the southwest and by noon in the far northeast. Across the southern portions of the state, snow will be heavy at times during the day. Models generally now agree that both surface and upper air temperatures will be supportive of an all-snow event, with the biggest question being how much precipitation falls. Fortunately, the overnight models have come into better agreement, with the southernmost models trending northward, and the northernmost models trending southward. Another consideration is that the thermal profile is colder in the north, as is almost always the case, so even if there is less precipitation, accumulations will be more efficient. So the big question is how much less the precipitation will be in the north. If the precipitation is significantly less, then accumulations would be lower, but if precipitation is just slightly less up north, then accumulations would probably be just a touch lower. For now, my general thinking is that most of the state gets an “advisory type event”, with the exception being northern Connecticut west of I-91. Up there, there is too much dry air, and the center of low pressure will be passing too far to the east and southeast.
Here is my latest thinking regarding accumulations:
Saturday night, a reinforcing cold shot will approach and bring a brief round of showers to the state, centered around the midnight hour. These showers start as rain and possibly change to sleet and snow, with the best chances of snow up north. No accumulations are expected, except possibly in the hills, where a coating may occur here or there.