I can feel the slide. Can you?
That sequence of days every fall in which pumpkin-spice-latte-holding, Banana Republic-flannel-wearing transitions into black coffee and an oversized L.L. Bean fleece.
Inherent in that slide are the first snowflakes outside of the mountains. The first snowfall that isn't just a freebie for the PR departments at Sunday River and Sugarloaf ("Look we're making snow! ....that will melt tomorrow afternoon...because,ya know, it's still October).
For many THOSE first flakes of the season will occur tomorrow night as a warm front approaches from the southwest.
The basic setup here is something known as Cold Air Damming:
Cold air damming is a setup in which cold air is supplied from a ridge of high pressure to the north and that cold air "banks" up against mountains to the west. It has varying degrees of strength and, during the middle of the winter, can produce some of our most prolific ice events.
But this time of the year it will simply keep enough cold air at the surface for precipitation to start out as snow on Thursday evening in lower elevations. This is a model snapshot for Thursday evening around 8 PM; notice the blue (snow) is not just confined to the mountains at first:
That cold air will hold on through most of the night before the marine influence takes over and starts driving the rain/snow line northwestward:
So if you live in the foothills and interior of Maine I'd expect some snow on Thursday night but rain by Friday mid morning at the latest.
Here's what I'm thinking for total snowfall:
And as far as driving goes; I wouldn't be too worried about it. Accumulation on asphalt is hard to come by in October and for it to happen you need some real Big Kid precipitation rates. Could it get a little "greasy" (hate it) in the higher terrain on Thursday night? Sure. But it's nothing to cancel plans over.
Unless you aren't a true Mainer.
Or you lived in Georgia for the past 3 years.
Theoretically speaking of course.
By the way, the coastline will be all rain, all the way, and it will be coming down heavily at times. This could be yet another positive step out of the drought:
The rain wraps up by late Friday afternoon. At this point the weekend looks decent. Not amazing, but decent. And we should return to slightly more mild conditions by mid next week.
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