Originally posted by rdewey
Just got done reviewing all of the data for the Great Lakes area...
Currently, it's snowing moderately with around one half inch in the past hour (it just started). Some locations in western lower MI have already seen 8 inches of snow...
Anyway, cross sections across MI show >80% RELH all the way through 500MB, with VV's of 4 -ub/s or lower for the next 12-15 hours (best between 00Z and 15-18Z tomorrow). This is all within the -20C (and lower) layer, when typically big flakes start to occur when you hit -15C, so we're good in that department. Cross sections also show a decent layer of negative EPV between 850MB and 600MB, and widely spaced theta-e surfaces, and again, well within the best snow growth layer. That lasts about 6-9HRS before moving off. That indicates a rather extended period that convective/banded snows could occur, but somewhat marginal vv's may inhibit actual lightning and thunder.
850/700MB lows track nearly overhead, which will enhance lift somewhat across the region, before being abosrbed into the east coast system around 18Z tomorrow. A strong TROWAL is in place, from New England to MI, with a strong easterly flow helping to pump Atlantic moisture into the system.
A look at the latest 21Z RUC continues to show this same scenario, and actually increases vv's by a whopping 1 -ub/s.
