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FOUS11 KWBC 251857
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
257 PM EDT SUN OCT 25 2026
VALID 00Z MON OCT 26 2026 - 00Z THU OCT 29 2026
..COLORADO
DAY 1...
EXITING UPPER LOW MOVING THROUGH COLORADO TONIGHT WILL BRING AN
ADDITIONAL FEW INCHES TO ELEVATIONS ABOVE 9000FT BEFORE ENDING BY
12Z MONDAY.
..NORTHERN PLAINS
DAYS 1-2...
AS THE UPPER LOW OVER COLORADO WEAKENS TO A TROUGH OVERNIGHT, A
SURFACE LOW WILL TRACK ACROSS KANSAS AND EASTERN NEBRASKA MONDAY
WITH ENOUGH COMMA HEAD PRECIP EXPANSION TO HAVE SOME SNOW BANDS ON
THE NORTHWEST SIDE OF THE PRECIP SHIELD. THIS SHOULD INTERSECT WITH
THE BLACK HILLS MONDAY ALONG WITH DYNAMIC ENOUGH BANDING FOR SOME
SNOW ACCUMULATION IN NORTHWESTERN SOUTH DAKOTA AND SOUTH-CENTRAL
NORTH DAKOTA. TEMPERATURES ARE MARGINAL, AND THE TREND WAS BEEN A
BIT SLOWER SUCH THAT MOST SNOW WOULD FALL BETWEEN 18-00Z WHEN IT IS
LESS LIKELY TO STICK. HOWEVER, ANY SNOW THAT FALLS BEFORE SUNRISE
OR AFTER SUNSET MONDAY WOULD HAVE A BETTER CHANCE OF ACCUMULATING.
MOST LIKELY FORECAST IS FOR A BROAD SWATH OF T-0.5" SNOW WITH SOME
POTENTIAL FOR AN AXIS OF 1-2" FROM THE BLACK HILLS NORTHEASTWARD.
WPC PROBABILITIES OF AT LEAST 4 INCHES OF SNOW ARE ABOUT 10% IN
OVER PARTS OF CENTRAL SD AND AROUND 20-40% FOR AT LEAST 2" OF SNOW.
..CASCADES AND NORTHERN ROCKIES
DAYS 1-3...
A MODESTLY ROBUST UPPER LOW JUST WEST OF THE WA COAST THIS EVENING
WILL MOVE INLAND INTO THE NORTHERN GREAT BASIN ON MONDAY WITH
TRAILING/REINFORCING SHORTWAVE TROUGHS MAINTAINING LOW PRESSURE
OVER THE NORTHWEST STATES FOR MUCH OF THE WEEK. HIGHER SNOW LEVELS
ABOVE 5000-8000FT AHEAD OF THE INITIAL UPPER LOW MONDAY WILL LOWER
TO 4000-5500FT OR SO BY WEDNESDAY AS ANOTHER STRONGER UPPER LOW
DIPS IN FROM THE BC COAST, WHICH COULD PUSH SNOW LEVELS TO AROUND
3500FT OVER THE WA CASCADES. WPC PROBABILITIES FOR AT LEAST 8
INCHES OF SNOW OVER THE NEXT THREE DAYS ARE >50% ABOVE ABOUT
5000-6000FT FROM NORTH TO SOUTH ALONG THE CASCADES FROM WA TO OR,
AND ABOUT 5000FT OVER IDAHO AND WESTERN MT. OVER NORTHWESTERN WY,
SNOW LEVELS WILL BE HIGHER AND SIGNIFICANT SNOW WILL BE ABOVE
9000FT.
BY WEDNESDAY, SNOW WILL LIKELY START TO FALL AT SOME OF THE PASS
LEVELS INCLUDING WASHINGTON, STEVENS, AND ALSO SNOQUALMIE PASSES.
THE PROBABILITY OF AT LEAST 2 INCHES OF SNOW AT SNOQUALMIE PASS
THROUGH 00Z THU IS ABOUT 70%.
FOR DAYS 1-3, THE PROBABILITY OF SIGNIFICANT ICE ACROSS THE CONUS
IS LESS THAN 10 PERCENT.
FRACASSO
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