427
FOUS11 KWBC 051814
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
214 PM EDT SUN APR 5 2026
VALID 00Z MON APR 06 2026 - 00Z THU APR 09 2026
..GREAT LAKES & NORTHEAST
DAYS 1-2...
COMPACT SHORTWAVE DIGGING OUT OF MANITOBA WILL RACE SOUTHEAST,
CROSSING THE UPPER MIDWEST AND GREAT LAKES MONDAY BEFORE BECOMING
EMBEDDED INTO THE MORE SYNOPTIC CYCLONIC FLOW ACROSS THE NORTHEAST
BY TUESDAY. THIS WILL HELP SPAWN A WEAK WAVE OF LOW PRESSURE ALONG
AN INVERTED SURFACE TROUGH, WITH LOCALLY ENHANCED MOIST ADVECTION
IN THE VICINITY OF THIS LOW LEADING TO A SWATH OF LIGHT TO MODERATE
SNOWFALL. THE HEAVIEST SYNOPTIC SNOW SHOULD BE GENERALLY NORTH OF
THE INTERNATIONAL BORDER, BUT CAA IN THE WAKE OF THIS IMPULSE WILL
PUSH 850MB TEMPS DOWN TO AROUND -15C, PRODUCING A FAVORABLE
ENVIRONMENT FOR LAKE EFFECT SNOW (LES) IN THE FAVORED NW SNOW BELTS
DOWNSTREAM OF THE GREAT LAKES. THE DURATION AND INTENSITY OF THIS
LES MAY BE SOMEWHAT MODEST, BUT SIGNIFICANT ACCUMULATIONS EXCEEDING
4" ARE STILL POSSIBLE (30-70% CHANCE) ACROSS THE WESTERN U.P. ON
D1, AND 10-50% ALONG THE CHAUTAUQUA RIDGE EAST OF LAKE ERIE ON D2.
ADDITIONALLY, ALTHOUGH ACCUMULATIONS ARE EXPECTED TO BE GENERALLY
LESS THAN 2", POST IMPULSE NW FLOW WILL CREATE SOME UPSLOPE
SNOWFALL ACROSS THE ADIRONDACKS AND GREENS ON D2.
..MISSOURI VALLEY/CORN BELT
DAY 2...
AN INTERESTING EVOLUTION MONDAY NIGHT INTO TUESDAY MORNING COULD
RESULT IN A VERY NARROW CORRIDOR OF HEAVY SNOWFALL FROM EASTERN
NEBRASKA INTO IOWA AND MISSOURI. A MODEST SHORTWAVE DROPPING ACROSS
THE CENTRAL ROCKIES WILL CAUSE WEAK HEIGHT FALLS AND BROAD
DIVERGENCE ACROSS THE REGION MONDAY NIGHT INTO TUESDAY. AT THE SAME
TIME, A POTENT NW TO SE ORIENTED JET STREAK WILL ARC SOUTHWARD ON
THE UPWIND SIDE OF A TROUGH MOVING OVER THE GREAT LAKES/NORTHEAST,
LEAVING FAVORABLE RRQ DIFFLUENCE OVERLAPPING THE BEST MID-LEVEL
DIVERGENCE. THIS MID- LEVEL PATTERN WILL PUSH A COLD FRONT THROUGH
THE REGION MONDAY, BUT IT IS LIKELY THAT THIS FRONT WILL BEGIN TO
KINK AND RETURN NORTHWARD WITH WARM ADVECTION TUESDAY MORNING AS
850MB FLOW RETURNS TO THE S/SW CREATING A NARROW CORRIDOR OF
IMPRESSIVE FGEN AS MOIST ISENTROPIC UPGLIDE ASCENDS THE BOUNDARY.
THE OVERLAP OF THIS MOIST ISENTROPIC ASCENT WITH THE RRQ OF THE JET
STREAK ALOFT WILL CREATE A NARROW STRIPE OF INTENSE 850-600MB FGEN,
CREATING A STREAK OF HEAVY PRECIPITATION. WITH THE MOST INTENSE
ASCENT EXPECTED TO LIFT INTO THE DEEPENING DGZ (50% CHANCE OF AT
LEAST 50MB OF DGZ DEPTH ACCORDING TO THE SREF), DYNAMIC COOLING
SHOULD OVERCOME THE GENERALLY MARGINAL THERMAL STRUCTURE, LEADING
TO A STRIPE OF HEAVY SNOW WITH SNOWFALL RATES POTENTIALLY REACHING
1"/HR. THERE REMAINS CONSIDERABLE UNCERTAINTY INTO THE PLACEMENT
OF THIS BAND DUE TO ITS NARROW NATURE, AS WELL AS THE INTENSITY OF
ANY OF THE SNOW, BUT WPC PROBABILITIES HAVE INCREASED, AND NOW
FEATURE A 30-50% CHANCE OF AT LEAST 2" TUESDAY MORNING, POTENTIALLY
LEADING TO A HAZARDOUS MORNING COMMUTE.
WEISS
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