Kitchen Sink On the Way

Possible significant ice storm on the way, especially across elevated areas...

Last night was an interesting one. Locations with a direct south wind were in the 40s all evening and slowly dropped into the upper 30s before the precipitation moved in, but areas that were protected from the wind dropped into the low and mid 30s and had black ice form on untreated surfaces, and then down along the CT river, there was actually a light north wind (talk about inversion!) with a temperature of 25 degrees at midnight. So there were some extremely icy spots this morning as I had feared, but now those are gone since we're all in the 40s out ahead of the cold front. Once that front moves through, the stage will be set for a potentially significant sleet/ice storm.

The cold front has just moved through Hanover as our winds have switched from SW to NW and the pressure is rising. Now we wait to see how much cold air bleeds into the valley. It will definitely work into the hills around 1000-2000 feet, but just how much settles in to the lower valley will play a big role on how much freezing rain accretes.

For what its worth, a winter storm warning is in effect from 7pm tonight till 4pm Wednesday afternoon, for the moderate to heavy precip that moves as in temps drop below freezing.

Here is my best guess:

Lebanon starts out with some sleet or icy snow and change over to sleet for a short period and then go over to plain sleet for a couple hours, and then freezing rain towards midnight. This is important because sleet is easier to drive on than freezing rain, and if the cold is more shallow initially, there will be more freezing rain, and driving conditions will be much worse tonight. Winds will be out of the east, and there will be classic cold air damming below 2000 ft. This means that the cold air will be very difficult to budge tomorrow, and temperatures will struggle to get above freezing. In the end, with a 10-15 south wind taking over Wednesday, I think Lebanon will change over to plain rain before the storm ends, but not before a decent amount of ice accretes to sidewalks, trees, powerlines, and roads. Locations protected from the wind probably won't get above freezing tomorrow, and elevated locations will prob stay below freezing, so there, significant ice accumulation is likely. The worst case scenario will be averted in the valley because of the speed of the storm, the eventual change to rain, but if you live up in the hills, power outages are definitely likely. Its possible that one inch of ice could build up on powerlines there. I'd say 1/4 to 1/2 inch will add up in the valley, depending on your location. The mixed precip should be out of here by late tomorrow afternoon.

Ice storms are more difficult to predict than snowstorms, so I'll have an update tonight.