Our little mixed precipitation event for next Tuesday has moved out of model fantasy range into the 5-day forecast realm. It’s not a storm that has me sitting at the edge of my seat but after an impressive streak of above normal temperatures it will be a notable snap back to reality.
It does look like enough cold air will be available for a little surge of moisture coming up from the southeast to produce a wintry mix. Too early to pin down how much but I wouldn’t be surprised to see a modest coating of snow followed by some sleet and freezing rain especially inland.
The GFS is on the slow and warm side of guidance with a weak front washing out over southern New England on Monday and another surge of moisture coming north for Tuesday night and Wednesday morning. All of this is ahead of an impressive trough/polar vortex diving south out of the Canadian Prairies toward to the Great Lakes.
The GFS is a mild solution with any frozen precipitation transitioning to rain. Weak cold air damming in New England thanks to a modest 1028-ish mb high over the Maritimes/New Brunswick would slow the surface 32F isotherm’s retreat north.
Most GEFS members are much chillier and farther south with the boundary. The op Euro is as well (and also much faster!). Here’s the op Euro from 12z.
The Euro is much flatter with the approaching trough/polar vortex upstream over Canada and the great lakes. This means a less amplified downstream ridge and the ability for the initial boundary on Monday to slide south a bit and not wash out so soon.
Even though the Euro is the more “wintry” solution for us it is actually the more reasonable/less extreme synoptic setup. The op GFS seems to be a bit too bullish dropping the PV due south into the Great Lakes with sub-480 1000-500mb thicknesses over Lake Superior at 144 hours.
As usual, when the op GFS and op Euro disagree, any the op GFS only has marginal ensemble support it’s time to embrace our friends overseas at ECMWF.
Cold and snow chances will be increasing over the last 2 weeks of January. More on that coming soon!