911
FOUS11 KWBC 241935
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
235 PM EST TUE FEB 24 2026
VALID 00Z WED FEB 25 2026 - 00Z SAT FEB 28 2026
..GREAT LAKES TO NEW ENGLAND
DAYS 1-3...
A CLIPPER-TYPE LOW PRESSURE WILL MOVE ACROSS ONTARIO, CANADA
TONIGHT BEFORE LIFTING ACROSS QUEBEC ON WEDNESDAY NIGHT. DOWNSTREAM
AND TO THE SOUTH OF THIS LOW PRESSURE, A SECONDARY LOW PRESSURE
WAVE MAY DEVELOP ALONG A TRIPLE POINT MOVING INTO NORTHERN MAINE,
HOWEVER, THE GREATEST ASCENT WILL BE ASSOCIATED WITH THE FRONTAL
STRUCTURE DUE TO WAA ALONG A WARM FRONT EAST OF THE TRIPLE POINT,
FOLLOWED BY CONVERGENCE ALONG THE FOLLOWING COLD FRONT INTO THE
MOISTENING AIRMASS. OVERALL, ASCENT APPEARS MODEST AND OF SHORT
DURATION DUE TO THE TRANSIENT NATURE OF THIS SYSTEM. HOWEVER, A
SURGE IN IVT REACHING 500 KG/M/S THANKS TO SWLY 850-500MB FLOW WILL
BRING PWS TO AROUND NORMAL VALUES, SUPPLYING MOISTURE TO BE WRUNG
OUT AS SNOWFALL ACROSS THE REGION. IN GENERAL, THIS SNOW WILL BE
LIGHT, WITH SOME MODERATE RATES POSSIBLE ACROSS COASTAL MAINE. WPC
PROBABILITIES D2 ARE LOW (10-30%) FOR AT LEAST 4 INCHES IN THIS
AREA, AS WELL AS THE HIGHER TERRAIN OF NEW ENGLAND AND UPSTATE NY.
ADDITIONALLY, SOME POST-FRONTAL LAKE EFFECT SNOW (LES) WILL
DEVELOP DOWNSTREAM OF THE GREAT LAKES THANKS TO INCREASED CAA.
WHILE MOST OF THIS SHOULD BE GENERALLY LIGHT, SOME HEAVIER BANDING
IS POSSIBLE EAST OF LAKE ONTARIO WHERE LAPSE RATES AND ASCENT ARE
MORE ROBUST. HERE, WPC PROBABILITIES FOR AT LEAST 4 INCHES OF SNOW
REACH 50-70%, WITH LOCALLY MORE THAN 8 INCHES POSSIBLE ACROSS THE
TUG HILL PLATEAU.
AFTER A BRIEF BREAK IN ACTIVITY D2 /WEDNESDAY NIGHT INTO THURSDAY/,
ANOTHER WAVE OF LOW PRESSURE IS EXPECTED TO DEVELOP ACROSS THE
MID-ATLANTIC AND THEN SHIFT RAPIDLY NORTHEAST INTO FRIDAY. THERE
REMAINS SOME LATITUDINAL SPREAD IN THE TRACK OF THIS FEATURE, WITH
A SUBTLE SOUTHWARD TREND NOTED IN RECENT GUIDANCE. THIS EVENT IS
EXPECTED TO BE FAST MOVING AND WEAK, BUT A FEW INCHES OF SNOWFALL,
REFLECTED BY WPC PROBABILITIES FOR 2+ INCHES REACHING 10-30% ACROSS
SOUTHERN NEW ENGLAND, ARE POSSIBLE. WHILE THIS IN ITSELF IS NOT
LIKELY TO BE IMPACTFUL, THE ADDITION OF THIS LIGHT SNOW ACROSS
AREAS STILL DIGGING OUT FROM THE HISTORIC BLIZZARD THIS WEEKEND,
COULD PROLONG OR AMPLIFY REGIONAL IMPACTS.
..NORTHERN AND CENTRAL ROCKIES
DAYS 1-2...
A STRUNG-OUT VORTICITY LOBE ASSOCIATED WITH A MODEST SHORTWAVE WILL
BRIEFLY BUCKLE THE MID-LEVEL FLOW ACROSS THE WEST THROUGH THURSDAY
MORNING. THE COMBINATION OF THESE WEAK HEIGHT FALLS WITH THE LFQ OF
AN ACCOMPANYING UPPER JET STREAK WILL DRIVE SYNOPTIC LIFT, WHICH
WILL BE ENHANCED ALONG THE STATIONARY FRONT DRAPED NE TO SW ACROSS
THE REGION. THIS WILL TRANSITION INTO A COLD FRONT AS THE SHORTWAVE
DIGS EAST, MOVING AWAY AND THEN OUT OF THE REGION DURING WEDNESDAY.
THE CUMULATIVE ASCENT ACCOMPANYING THIS EVOLUTION WILL ACT UPON A
MOISTENING COLUMN AS IVT SURGES TOO 400-500 KG/M/S, WHICH WITH A
PRONOUNCED ZONAL COMPONENT WILL ALLOW IVT TO SPILLOVER WELL INTO
THE ROCKIES, LEADING TO IVT ABOVE THE 99TH PERCENTILE, AND EVEN THE
HIGHEST WITHIN THE CFSR DATABASE FOR PORTIONS OF THE ROCKIES. WHERE
THE MOST SIGNIFICANT LIFT OVERLAPS THIS MOISTURE, THE RESULT WILL
BE HEAVY SNOW, ESPECIALLY ABOVE 6000 FT WHICH WILL RESULT IN
IMPACTFUL ACCUMULATIONS ACROSS ID/WY/UT/CO. WPC PROBABILITIES ARE
HIGH (>70%) FOR AT LEAST 7 INCHES IN PARTS OF THE SAWTOOTH/SALMON
RIVER RANGES, THE TETONS AND WIND RIVERS, THE UINTAS, AND MUCH OF
THE CO ROCKIES. LOCALLY MORE THAN 12 INCHES IS POSSIBLE (30%
CHANCE) IN THE WIND RIVERS, TETONS, AND PARK RANGE OF CO.
..CASCADES INTO NORTHERN ROCKIES
DAYS 2-3...
GENERALLY WEST TO NORTHWEST MID-LEVEL FLOW WILL FUNNEL MODEST
MOISTURE ONSHORE LATE THIS WEEK AS IVT PUSHES TO AROUND THE 90TH
CLIMATOLOGICAL PERCENTILE FROM BRITISH COLUMBIA EAST-SOUTHEAST
TOWARDS MONTANA. MODEST ASCENT, MOSTLY DRIVEN BY JET-LEVEL
DYNAMICS, WILL ACT UPON THIS MOISTURE TO PRODUCE MODERATE
PRECIPITATION ACROSS THE CASCADES WHERE UPSLOPE ENHANCEMENT WILL
ALSO OCCUR. THIS IS REFLECTED BY WPC PROBABILITIES FOR 6+ INCHES
THAT REACH 30-50% IN THE NORTHERN WA CASCADES.
FARTHER EAST INTO D3, A COLD FRONT DIGGING OUT OF CANADA WILL ARC
ACROSS THE NORTHERN ROCKIES WHILE UPPER LEVEL SUPPORT PERSISTS.
THIS MAY RESULT IN A STRIPE OF HEAVIER SNOWFALL FROM THE NORTHERN
ROCKIES ALONG THE INTERNATIONAL BORDER INTO THE HIGH PLAINS, BUT
CONFIDENCE IN EXACT PLACEMENT REMAINS UNCERTAIN. CURRENT WPC
PROBABILITIES ARE 50-70% FOR 6+ INCHES IN THE HIGHER NORTHERN
ROCKIES, WITH A STRIPE OF 10% PROBABILITIES FOR 4+ INCHES EXTENDING
EASTWARDS INTO THE HIGH PLAINS OF MT.
WEISS
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