A period of heavy snow likely

The 18z NAM came in even more robust with secondary low pressure near New York City assisting in the development of an area of heavy overrunning precipitation in New England. Again, the period I've been targetting looks good: In the three hour period from 9am to noon, we could see accumulations around 6" in Keene. The NAM is calling for intense omega intersecting the snow growth zone around 500mb supporting great dendritic growth and a period of high ratios, in addition to a huge delivery of moisture.

The next big question is when we can expect precipitation changes. There are too areas in the column to watch. The first is up near 700mb where an inversion may poke above freezing, and the second is in the boundary layer. The GFS warms the boundary layer faster than the NAM, switching precipitation over to rain by 1pm. Depending on how fast temperatures aloft warm, in that layer near 700mb, we could see a period of sleet and freezing rain. Again, I don't expect this to rob us of much snow, as the best moisture and forcing should be through already.

Snowfall forecast for Keene still stands at 6" to 9". Updates this evening.

--- Snowday Outlook ---
An hour earlier start to the snow would raise my confidence considerably. As it stands, snow will be falling at 530, with a coating to an inch probable before 7am. After that, conditions will deteriorate pretty quickly. I think chances for a snowday look pretty good at this point.