652
FOUS11 KWBC 011822
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
222 PM EDT THU MAY 1 2025
VALID 00Z FRI MAY 02 2025 - 00Z MON MAY 05 2025
..SIERRA NEVADA
DAY 3...
A POTENT CLOSED LOW WILL DIG ALONG THE CA COAST SATURDAY INTO
SUNDAY, WITH RAPID AMPLIFICATION OF THIS FEATURE EXPECTED BY SUNDAY
MORNING. THIS IS REFLECTED BY NAEFS HEIGHT ANOMALIES FALLING TO
BELOW THE 1ST PERCENTILE WITH RESPECT TO 700-500MB HEIGHTS OVER
SOUTHERN CA BETWEEN 12Z SUNDAY AND 00Z MONDAY. ALTHOUGH THE
ACCOMPANYING JET STREAK WILL INTENSIFY AS WELL AS IT PIVOTS AROUND
THE UPSTREAM SIDE OF THIS TROUGH AND THROUGH THE BASE, THE OVERALL
EVOLUTION WILL KEEP THE MOST INTENSE ASCENT DISPLACED SOUTH/EAST OF
THE SIERRA, BUT SUFFICIENT LIFT AND INCREASING MOISTURE WILL STILL
RESULT IN PERIODS OF SNOWFALL D3. SNOW LEVELS DURING THIS TIME
WILL BEGIN AROUND 8000-9000 FT, SO ONLY THE HIGHER SIERRA PASSES
WILL BEGIN AS SNOW, BUT AS THE UPPER LOW DIGS ACROSS CA, SNOW
LEVELS ARE PROGGED TO FALL TO AS LOW AS 7000 FT, BRINGING AT LEAST
SOME ACCUMULATIONS TO DONNER PASS AS WELL. OVERALL, SIGNIFICANT
SNOWFALL ACCUMULATION WILL BE CONFINED TO ABOVE PASS LEVEL, WHERE
WPC PROBABILITIES FOR MORE THAN 6 INCHES OF SNOW ARE AS HIGH AS
60%, BUT LIGHT SNOW DOWN TO MOST SIERRA PASS LEVELS IS ALSO LIKELY
BEFORE PRECIP WINDS DOWN BY SUNDAY MIDDAY.
THE PROBABILITY OF SIGNIFICANT FREEZING RAIN ACROSS THE CONUS IS
LESS THAN 10%.
WEISS/SNELL
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