Expectations are for heavy snow impacting the Thursday Evening
commute across the Detroit Metro Area and points south, as strong
upper level wave comes out of southern Arizona and becomes absorbed
within the strong southwest flow of the northern stream trough.
Combined 6hr 500 MB height fall center looks to be tracking along the
southern Michigan/northwest Ohio border, and favor heaviest band of
snow along/just above 850 MB shear axis/fgen zone. Short duration
(~21-3z) of the intense lift, but at least several hours of snowfall
rates of 1+ inch/hr at any given location. Very sharp NW-SE moisture
gradient in place, but still strong consensus of 4 g/kg in the
850-700 MB layer lingering around I-94 corridor in the early evening
before aggressive drying then takes place for the rest of the evening
and Thursday night. Despite the 12z Euro coming in rather
progressive and unimpressive from a QPF perspective (compared to
RAP/NAM), have elected to issue a winter storm warning for Detroit
Metro Area and points south for 4-8" (especially after giving the 18z
NAM a quick peak, which is very agressive). With the peak timing
occuring during the Thursday evening commute, and some wind and drier
snow on the back end, seems like this event will be highly impactful
for travel concerns, especially if a layer of ice develops under the
snow as well.
Far southeast areas TTF-DET could still be under influence of the
leftover marginal warm layer aoa 5000 feet to lead to sleet
initially Thursday afternoon, which would cut down on snow amounts
for those areas. On flip side, locations north of I-94 have chance
to overachieve if snow to liquid ratios end up higher than forecast
or if we are able to tap into the instability/negative EPV above the
frontal zone indicated in cross sections.
very interesting