Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
439 PM EDT Sun Mar 10 2024

Valid 00Z Mon Mar 11 2024 - 00Z Thu Mar 14 2024

...Northeast...
Day 1...

Northern stream low over PA this afternoon will continue to swing
east through this evening before occluding north into the Gulf of
Maine as it phases with a trough from the southern stream that is
currently over Maine. This track and continued forcing will keep
allowing the surface low to develop as it lifts north from eastern
Maine into New Brunswick tonight. Cyclonic flow over the eastern
Great Lakes and over interior sections of northern New York and
New England will continue to allow wrap around snow, particularly
into the north side of the Adirondacks and the Green Mtns where
Day 1 PWPF for >6" are 50-90%. Weakening snow bands lift out of
Maine Sunday night as the low tracks northeast from Nova Scotia.

Snow Squalls: Continued gusty snow showers can be expected under
the upper low currently over eastern PA through into this evening.
Areas of southern New York, New Jersey, eastern Pennsylvania and
even northern Maryland/Delaware can expect showers. The flash
freeze concerns will continue to be over central/northeast PA into
southern Upstate NY where conditions are colder behind a
reinforcing cold front. Here, rapid reductions of visibility and
flash freezing of roadways will make for difficult travel
conditions.


...The West...
Days 1-3...

An active pattern continues over the Northwest through Tuesday
with the focus shifting to the central/southern Rockies on
Wednesday.

Confluent flow and WAA surging across the Northwest ahead of an
mid-level trough that is reaching the PacNW coast this afternoon
will promote snows over the Northern Rockies down to northern
California terrain tonight with snow levels generally 3000-4000
ft. Moisture ahead of the next wave reaches the PacNW coast Monday
afternoon with Cascades snow levels around 3000ft. Day 1 PWPF for
>8" is 40-80% for the Olympics, Cascades and a few ranges in
central and far northern ID as well as northwest MT.

Generous moisture advection with offshore PW of 1" surges into the
PacNW with the next system Monday afternoon with Monday evening
snow levels up around 4000ft for the Cascades before decreasing to
2500-3000 ft Tuesday under the upper trough as precip rates
diminish. This moisture surge crosses the northern Intermountain
West with Day 2 PWPF for >8" much more expansive than Day 1 with
50-90% values for the entire Cascades, Olympics, the
Shasta/Siskiyou, and northern Rockies in central ID/northeast OR
and along the ID/MT border (the Bitterroots).

Increasing ridging off the West Coast allows the PacNW wave to dig
south over the Intermountain West Tuesday night through Wednesday,
closing into a mid-level low in the process. This creates a
positively-tilted trough extending from the northern Plains to the
Desert Southwest which is similar to the system last week (that
produced heavy snow over the central Plains), but this one is much
more potent and focused west. Another inverted trough east of a
surface high pressure wedge down the east side of the Rockies
develops, but farther west than before which should allow snow to
focus over the CO Rockies and then eastern slopes/the CO High
Plains.

Day 3 PWPF for >8" are 40-60% over the Bighorns of WY, portions of
the Wasatch and southern UT ranges, and most of the
northern/western CO Rockies.


The probability of receiving at least 0.1" ice is less than 5%
across the CONUS through Day 3.


Jackson