Overnight there will be much more data arriving to give us an even better idea of some of the storm's specifics. Saturday morning I will be updating the start and end time for the storm, tweaking the accumulation map, and looking at when any change to sleet and rain may occur. I expect much of the region to end up with between six and ten inches of snow. 80% of the snow will fall in the window between 10PM Saturday night and 7AM Sunday. Boston should see about 6 inches with a couple of inches more or less depending on exactly how much warm air mixes into the system between 3AM and 5AM Sunday.
I'll be updating the snow forecast as it changes on Twitter at @growingwisdom Please follow me there. Feel free to comment or ask questions too.
Overnight is will be very cold, winds will be brisk pushing wind chill levels below zero in many places. The actual thermometer will approach zero in the colder areas, but even Boston will drop to 12F by Saturday morning.
When you awake, there could be a bit of dim sunshine to start the day, but clouds will thicken. There could be flurries during the day, but the main event arrives after dark. If you are planning on doing some shopping, know you might see snow in the air, especially along the coast.
Some of you hate driving in snow and I would advise you do be off the roads by dark. From about 3PM to 6PM snow will overspread the area and become steadier and heavier as the night progresses. It will be cold with temperatures in the upper teens to mid-20s north to south.
The night is going to be snowy, but not a blockbuster type of storm where you can't get around. I think visibility late at night between 11PM and 5AM could lower to under 1/4 a mile at times, but if you take it slowly, you should be able to attend that holiday gathering and get home safely before the worst of the storm. The rain snow line will be moving northward during the night and temperatures will actually rise or remain steady.
Our storm system will be tracking up the coastline Saturday night and early Sunday morning. We don't know the exact tract of any weather system until very close to the actual event. At this point, it seems more and more likely Boston and points north and west will stay mostly snow. The ultimate track of the low will determine how much snow areas south of Boston and over Cape Cod and the Islands receive before any change or mix with rain and sleet. The closer to Nantucket the center of the storms passes, the more warm air can make it inland. This will impact the final snow totals a great deal.
The map shows a projection of where the rain/snow line, also called the "coastal front", is expected early Sunday morning. If this line moves further inland amounts will be cut, if it stays offshore, Boston could see 10 inches of snow.
I expect the snow to wind down Sunday morning and there may even be some sunshine later in the day. This is the radar shot for early Sunday. Again, this is still preliminary. It won't be very cold immediately behind the system immediately so cleaning up Sunday will be easier. Temperatures are going to remain below normal for much of the time into Christmas. Thereafter, there are hints of a relaxing of the cold, but Christmas itself has the potential to be quite cold.
How much snow?
The map below is based on the rain/snow line making it to about Boston for a few hours during the storm. If the line stays south, say over Plymouth or even the Cape Cod Canal, the heavy snow line I have will push southward to that spot and bring the heaviest band over Boston. This is possible and I will update the map further throughout the day and of course tomorrow prior to the storm.
It looks cold and dry for Monday with a bit of snow possible Tuesday, but not a big storm.
Outdoor project this weekend
In this video I show you a project you can do this weekend and bring the kids along too.
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