Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
308 AM EDT Sun Apr 7 2024

Valid 12Z Sun Apr 07 2024 - 12Z Wed Apr 10 2024


...Northern High Plains/Rockies...
Days 1-2...

Mature, wrapped-up, stacked occluded cyclone over north central
Nebraska this morning will eject eastward today with a decrease in
QPF coverage/intensity through the day into the overnight hours
from eastern Wyoming into the Dakotas. Thermal profiles will
continue to favor snow over Wyoming into the Black Hills but rain
over much of the Plains until perhaps overnight when colder air
gets drawn in from the north (minor accumulation). Lower-level
FGEN/deformation axis and a surface boundary will be the focus for
heavier snow this morning over the Bighorns and Black Hills into
the Laramie Mountains to the Pine Ridge in northwestern NE (aided
by upslope flow into these elevated areas) with continued blowing
snow on N to NW winds. By Monday morning, lingering moisture and
vort maxes rotating around the departing upper low will maintain
light snow across the mountains with only minor accumulations by
then. Over the next 36 hours, WPC probabilities for an additional 8
inches of snow are >50% over the Bighorns eastward to the Black
Hills, with much lower probabilities in the shadowed areas.


...Northwest...
Days 2-3...

Incoming jet off the northeast Pacific will bring in some moisture
to the Olympics and WA Cascades with snow levels rising to
4500-5000 ft Mon/Tue, keeping much of the accumulating snow above
the passes. Additional snow is forecast over northern ID into
northwestern Montana, especially above 5500ft or so.


The probability of significant icing of at least 0.25 inches is
less than 10 percent.


Fracasso