558
FOUS11 KWBC 051821
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
221 PM EDT SUN OCT 5 2025
VALID 00Z MON OCT 06 2025 - 00Z THU OCT 09 2025
..NORTHERN ROCKIES
DAY 1...
BROAD POSITIVELY TILTED UPPER TROUGH ACROSS THE NORTHERN ROCKIES
WILL MAINTAIN PREVALENCE OVER THE NEXT 12-24 HRS WITH A STRONG
SURFACE RIDGE PRESSING DOWN OUT OF ALBERTA IN TANDEM WITH A
SHORTWAVE PROGRESSING AROUND THE TROUGH BASE, CURRENTLY ANALYZED
OVER THE SOUTHERN PORTION OF THE ID/MT BORDER. FORECAST HAS BEEN
LARGELY UNCHANGED WITH THE CURRENT RADAR/SAT COMPOSITE INDICATING A
PREVAILING UPSLOPE REGIME ACROSS THE ABSAROKA AND NORTHERN BIG
HORNS WITH AN EXPECTATION FOR PRECIP TO IGNITE OVER THE COURSE OF
THE AFTERNOON AND EVENING AS WE MOVE INTO THE WIND RIVER RANGE.
THIS IS THANKS TO THE PROGRESSION OF THE SHORTWAVE MIGRATING OUT OF
ID LEADING TO THE FINAL CHAPTER IN THE FIRST HEAVY SNOW EVENT OF
THE SEASON FOR THE NORTHERN ROCKIES. ADDITIONAL ACCUMULATIONS OF
4-8", LOCAL TO 12" ARE ANTICIPATED ACROSS THE HIGHER TERRAIN
(>8000FT MSL) WITH A RESPECTABLE 3-6" FOR AREAS BETWEEN
5500-7000FT MSL. LIGHT SNOW ACCUMULATIONS WILL BE FORECAST BELOW
5000FT MSL, BUT IMPACTS WILL BE NEGLIGIBLE IN THE GRAND SCHEME.
WPC PROBABILITIES FOR THE REMAINDER OF THE EVENT (00-12Z MONDAY)
STILL HOVER BETWEEN 50-70% FOR AN ADDITIONAL 4+" OVER THE WIND
RIVER RANGE, BUT A SURGE OF DRIER AIR WITH THE INCOMING SURFACE
RIDGE AND VACATING SHORTWAVE WILL LEAD TO A QUICK DECAY OF SNOW
CHANCES FROM NORTH TO SOUTH AS WE MOVE THROUGH THE REST OF THE D1.
BY TOMORROW MORNING, SNOW WILL TAPER OFF TO JUST SCATTERED LIGHT
SNOW WITH ONLY SMALLER ADDITIONAL ACCUMS EXPECTED. THE THREAT FOR
WINTER WEATHER WILL BE OVER PRIOR TO 18Z.
THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.
KLEEBAUER
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