Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
443 AM EDT Thu Mar 17 2022

Valid 12Z Thu Mar 17 2022 - 12Z Sun Mar 20 2022

...Central Rockies and Southern Plains...
Day 1...

A leading shortwave trough will push east of the southern Rockies
this morning while a reinforcing shortwave trough will dig
southeast across NM this afternoon. Lee cyclogenesis over the
southern High Plains combined with high pressure over the interior
Northwest will continue to bring convergent bands of snow to shift
south over CO and into northeastern NM this morning before the
trough and surface low shift over the southern Plains this
evening. Snow probabilities are moderately high over the Raton
Mesa along the CO/NM border and the Sangre de Cristos with low
values over the Palmer Divide. As the sfc low shifts east across
the southern Plains this afternoon/evening, ample moisture will
wrap around the system. While marginal thermal profiles are
expected on the NW side of the storm, there is an expectation for
snow bands to dynamically cool enough to warrant accumulations.
Day 1 snow probabilities for 2" are around 10 percent over
portions of central and western KS, but a few inches are possible
in localized areas. The GFS has been consistently more bullish
with this snow band potential system over the southern Plains to
Midwest.


...Midwest to Great Lakes and northern New England...
Days 2-3...

System organizing/turning northeast over the southern Plains this
evening will ride a southwesterly the upper trough and jet move
into the Great Lakes and Northeast Friday/Friday night. Northwest
side of the precip field will lie astride marginally-supportive
temperatures as cold air is drawn southward into the region.
Deformation band indicating by some of the models would support
periods of snow that could accumulate on at least grassy surfaces
and especially overnight. Guidance continues to indicate potential
for another area of deformation snow over parts of IA into WI
later Friday through Friday night as the surface low continues
northeastward and the upper low weakens into an open trough. WPC
probabilities for over 2" are around 10 to 15% over much of
southern/eastern WI.


...Pacific Northwest...
Days 1-3...

Weakening shortwave moving into today into early Day Thursday will
bring generally light snow to elevations above ~4000ft over the
Washington Cascades into northern Idaho and northwestern Montana.
By Friday night, a stronger trough and attendant cold front will
bring a leading surge of modest moisture (precipitable water
values up to +1 sigma) to the Northwest, including into northern
California. Snow levels will fall below 4000ft behind the front as
precipitation wanes over WA/OR. Snow levels over the Sierra Nevada
will start near 5000-6000ft late Saturday when snow starts to
accumulate a few inches over higher elevations in this brief bout
of snow.


For Days 1-3, the probability for receiving at least 0.10" of
freezing rain is less than 10 percent across the lower 48.

Jackson