348
FOUS11 KWBC 282111
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
511 PM EDT FRI MAR 28 2025
VALID 00Z SAT MAR 29 2025 - 00Z TUE APR 01 2025
..NORTHERN/CENTRAL ROCKIES
DAYS 1/2...
A SHORTWAVE TROUGH EJECTING FROM THE REMNANT/OCCLUDED LOW OFF WA
CROSSES THE PACNW TONIGHT AND THE GREAT BASIN THROUGH SATURDAY
NIGHT. THIS MAINTAINS MOISTURE SPREADING ACROSS THE NORTHERN GREAT
BASIN AND ROCKIES WILL BEGIN TO INTERACT WITH A DEVELOPING LOW-TO-
MID LEVEL BAROCLINIC ZONE AND PERIODS OF ENHANCED FORCING
ASSOCIATED WITH THE INLAND MOVING TROUGHS TO PRODUCE LIGHT-TO-
MODERATE PRECIPITATION, INCLUDING MOUNTAIN SNOW FROM THE NORTHERN
TO THE CENTRAL ROCKIES. PRECIPITATION COVERAGE IS EXPECTED TO
INCREASE TONIGHT, WITH UNSETTLED WEATHER CONTINUING INTO SUNDAY
WITH A WEAK AREA OF CONVERGENCE ON SUNDAY BETWEEN WESTERN MT AND
NORTHERN CO. SNOW LEVELS BEGINNING ABOVE 5000FT IN THE NORTHERN
ROCKIES ARE FORECAST TO DIP BELOW 4000FT IN SOME LOCATION BY LATE
SATURDAY. IN THE CENTRAL ROCKIES, SNOW LEVELS WILL DROP TO
7000-8000FT IN THE COLORADO RANGES AND AROUND 5000-6000FT ACROSS
NORTHERN UTAH. WPC DAY 2 PROBABILITIES FOR >8" OF SNOW ARE
GENERALLY 40-70% OVER SOUTHWEST MT, THE ABSAROKAS AND WIND RIVER
RANGE, AND THE PARK RANGE AND MEDICINE BOW MOUNTAINS OF NORTHERN CO.
..SOUTH DAKOTA, MINNESOTA, AND NORTHERN WISCONSIN/MICHIGAN
DAYS 1/2...
..BACK TO BACK IMPACTFUL WINTER SYSTEMS THROUGH SUNDAY
INVERTED TROUGH FROM CENTRAL HIGH PLAINS UP THROUGH LOWER MI
PERSISTS TONIGHT AS AN UPPER LOW APPROACHING THE NORTHERN ROCKIES
THIS AFTERNOON ALLOWS LEE-SIDE CYCLOGENESIS TO FOCUS OVER WESTERN
KS THROUGH SATURDAY MORNING WITH A MORE POTENT LOW TRACK FROM KS TO
MI SATURDAY THROUGH SUNDAY EVENING.
A VERY STRONG BAROCLINIC ZONE (IT'S CURRENTLY LOW 80S IN SOUTHWEST
MN AND MID 20S IN THE ARROWHEAD) MAINTAINS COLD OVER NORTHERN
MN/WI/THE U.P. THROUGH THIS WEEKEND WHILE WARM AIR RIDES OVER THE
BOUNDARY TO THE SOUTH. ONGOING WINTRY MIX CONTINUES TONIGHT WITH A
SLOW SOUTHWARD SHIFT. DAY 1 ICE PROBS FOR >0.1" ADDITIONAL AFTER
00Z IS ABOUT 20% OVER FAR NORTHERN WI INTO THE WESTERN U.P., BUT
50-80% OVER FAR NORTHEAST WI AND CENTRAL/EASTERN U.P. AND NORTHERN
L.P. WITH 70% PROBS FOR >0.25" OVER THE NORTHERN L.P.
THE DEVELOPING LOW TRACK OVER KS ON SATURDAY ALLOWS
FGEN/DEFORMATION BANDING TO DEVELOP OVER OVER SOUTHWEST SD INTO
NORTHWEST NEB. LOCALIZED BANDING SHOULD OVERCOME THE STRONG MARCH
DIURNAL INSOLATION, BUT THAT SHOULD BE FAIRLY NARROW. DAY 1.5 SNOW
PROBS FOR >4" ARE 30-60% MAINLY OVER SOUTH-CENTRAL SD AND THE BLACK
HILLS.
THE IMPACTFUL WINTRY WEATHER CONTINUES RESUMES SATURDAY NIGHT OVER
MN/WI/MI AS SNOW BANDS INTENSIFY IN THE INCREASING RIGHT ENTRANCE
JET DYNAMICS AND THE COMMA HEAD FORCING FROM THE LOW TRACKING OVER
IA. THESE SNOW BANDS ARE INCREASINGLY LIKELY OVER NORTH-CENTRAL MN,
FAR NORTHERN WI AND WESTERN/CENTRAL U.P. WHICH WOULD PUT HEAVY WET
SNOW OVER AREAS CURRENTLY GETTING ICE ACCRETION. DAY 2 SNOW PROBS
FOR >4" ARE 30-60% FROM THE SISSETON HILLS OF NORTHEAST SD THROUGH
THE CENTRAL U.P. AND NORTH SHORE OF MN WITH 50-70% PROBS FOR >6"
OVER FAR NORTHERN WI THROUGH THE KEWEENAW PENINSULA. THE WINTRY MIX
SWATH IS JUST SOUTH OF THE SNOW WITH ACCUMULATING SLEET AND ICE
EXPECTED TO EXPAND SOUTH AS THE COLD AIR WINS/ADVANCES. DAY 2 ICE
PROBS FOR >0.25" ARE 30-70% FROM CENTRAL MN THROUGH NORTHERN
WI/SOUTHERN/EASTERN U.P. AND THE NORTHERN L.P. WITH A MAX AROUND
80% IN NORTHEAST WI.
..NORTHEAST
DAYS 1-3...
...PROLONGED WINTRY MIX OVER NORTHERN NY/NEW ENGLAND THROUGH
SUNDAY...
THE INVERTED TROUGH CAUSING A WINTRY MIX OVER THE NORTHERN GREAT
LAKES TODAY SPREADS EAST OVER NORTHERN NY AND CENTRAL NEW ENGLAND
THIS EVENING WITH THE STRONG BAROCLINIC ZONE MAINTAINING FGEN
PRECIP/WINTRY MIX THROUGH THIS WEEKEND FOR PORTIONS OF NEW
ENGLAND. THE APPROACHING LOW CROSSES NEW ENGLAND ON MONDAY.
THE HEAVY SNOWFALL THREAT PEAKS LATE TONIGHT FROM LAKE CHAMPLAIN
THROUGH NORTHERN NH INTO SOUTHERN MAINE AS A JET MAX PASSES TO THE
NORTH OF NEW ENGLAND AND 925-850MB WAA IS STRONGEST. 12Z HREF
DEPICTS 30-40% CHANCES FOR 1"/HR SNOWFALL RATES FROM 06Z TO 13Z
SATURDAY ACROSS THE NORTHERN TIP OF NY AND NORTHERN VT/NH. DAY 1
WPC SNOWFALL PROBABILITIES FOR >6" ARE 30-60% MAINLY OVER THE
NORTHERN GREENS AND THE PRESIDENTIAL RANGE OF NH.
SOUTH OF THIS HEAVY SNOW THREAT BETWEEN THE NORTHERN ADIRONDACKS
AND MUCH OF CENTRAL/SOUTHERN VT AND NH, 850-750MB WARM NOSE ALLOWS
FOR A TRANSITION ZONE OF SLEET/FREEZING RAIN. AFTER THE BRIEF
BURST OF HEAVIER PRECIP EARLY SAT, FORCING WEAKENS AND THERE IS
LEFT A WEAK STREAM OF MOISTURE OVERRUNNING A CAD SIGNATURE DUE TO A
STRONG 1030MB HIGH SITUATED OVER THE JAMES BAY. THIS POTENTIALLY
SIGNIFICANT ICING THREAT IS EXPECTED TO LINGER THROUGH SUNDAY UNTIL
THE SURFACE LOW ACROSS THE MIDWEST BEGINS TO STRENGTHEN AND PUSH
WARMER AIR NORTHWARD ACROSS NEW ENGLAND BY SUNDAY EVENING.
HOWEVER, THE CAD SIGNATURE IN PLACE WILL CONTINUE TO SUPPORT
FREEZING RAIN ACROSS THE TYPICALLY COLDER VALLEY LOCATIONS AND
AREAS BANKED ALONG THE GREEN/WHITE MOUNTAINS. DAY 1 WPC
PROBABILITIES FOR >0.25" ICE (ENDING 00Z/SUN) ARE 40-70% FOR THE
THOUSAND ISLANDS AREA, THE NORTHERN ADIRONDACKS AND SOUTH-CENTRAL
VT/NH. THIS IS FOLLOWED BY DAY 2 VALUES OF 20-50% FOR AN ADDITIONAL
0.25" OVER THE SAME AREAS WITH SOME EXPANSION THROUGH CENTRAL
VT/NH.
..OR CASCADES...KLAMATH...AND NORTHERN/CENTRAL SIERRA NEVADA
DAY 3...
THE NEXT COLD CORE LOW DRIFTS TOWARD OR, BUT REMAINS OFFSHORE
SUNDAY THROUGH MONDAY. A RICH PLUME OF MOISTURE SHIFTS INLAND
SUNDAY WITH RENEWED ENHANCEMENT FROM AN EJECTING SHORTWAVE TROUGH
SUNDAY NIGHT PRODUCING HEAVY PRECIP OVER THE NORTHERN HALF OF CA
MONDAY. DAY 3 SNOW PROBS FOR >8" ARE 40-90% IN THE SOUTHERN OR
CASCADES, THE KLAMATH/TRINITY ALPS, AND NORTHERN/CENTRAL SIERRA
NEVADA WITH SNOW LEVELS OF 5000-6000FT SUNDAY DROPPING TO
4000-5000FT BY MONDAY MORNING.
JACKSON
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