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

Valid 00Z Mon Apr 08 2024 - 00Z Thu Apr 11 2024


...Northern High Plains/Rockies...
Day 1...

Mature, wrapped-up, stacked occluded cyclone over north central
Nebraska this afternoon will eject northeastward tonight with a
decrease in QPF coverage/intensity through Monday from eastern
Wyoming into the Dakotas. Thermal profiles will continue to favor
snow over Wyoming into the Black Hills but mostly rain over much
of the Plains until 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
evening 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 higher elevations
of Black Hills, with much lower probabilities in the shadowed
areas.


...Northwest...
Days 1-2...

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/Snell