Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
416 PM EDT Fri Mar 25 2022

Valid 00Z Sat Mar 26 2022 - 00Z Tue Mar 29 2022

...Upper Midwest/Great Lakes/Central Appalachians...
Days 1-3...

Strong cyclonic flow over the region with embedded potent
shortwave energy will lead to a busy and wintry regime through
this weekend featuring heavy Lake Effect Snow (LES), upslope snow,
and potentially convective snow showers that could lead to
localized hazardous conditions.

Water vapor imagery this afternoon shows a potent shortwave trough
dropping quickly southeast out of the Upper Mississippi River
Valley and will reach the Chicago area by this evening. This
feature is expected to close off at 500 mb as it swings through
the lower Great Lakes tonight into early Saturday. The forcing for
ascent combined with available moisture will produce light snow
across the Great Lakes and central Appalachians. The more
impressive snowfall totals are favored in the W/NW snow belts off
Lake Superior, Michigan, and Erie where the cold air advection
becomes quite impressive behind the surface front. Steepening low
level lapse rates and supportive lake temperatures should lead to
enhanced local ascent and an extended period of lake effect snow.
The western lakes will see the greatest totals during D1 /ending
00Z Sunday/ while the setup will continue to favor Lake Erie LES
through early D2. WPC probabilities for 4 inches or more are
moderate to high in the favored W/NW snow belt areas off the lakes
with a slight signal for 8" totals off Lake where a prolonged
period of LES is expected.

The anomalously deep/cold heights aloft swinging overhead and W/NW
flow regime will also drive impressive upslope snow over the
favored high terrain of the central Appalachians of WV into the SW
portion of the Laurel Highlands. WPC probabilities for 4 inches or
more are above 60-80 percent and total snowfall through early next
week could total 8-10" with isolated amounts exceeding a foot.

Finally, isolated to scattered convective snow showers are likely
through Saturday evening as the main PV anomaly swings through.
Nearly saturated column with steep lapse rates and some marginal
but sufficient instability favors convective snow showers through
this evening over the Great Lakes and then moving toward the
eastern Great Lakes and Northeast tomorrow and tomorrow evening.
Some isolated stronger convective showers or snow squalls will be
possible with snow rates approaching 1"/hr briefly which could
lead to hazardous travel due to limited visibility.


...Sierra Nevada...
Day 3...

Anomalously deep upper low will approach California during the D3
period and a plume of above normal moisture will stream onshore
and directed at the Sierra Nevada. Favorable forcing for ascent /
upper diffluence interacting with the moisture will combine to
produce widespread precipitation late Sunday into Monday. This
system is relatively warm so snow levels will be high, but the
higher peaks of the Sierra are expected to see heavy snow where
the latest WPC probabilities for 4 inches or more are high for the
highest peaks with a slight to moderate signal already for 8" or
greater totals during D3.


Weiss/Taylor