492
FOUS11 KWBC 281813
QPFHSD
PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
213 PM EDT TUE APR 28 2026
VALID 00Z WED APR 29 2026 - 00Z SAT MAY 02 2026
..CENTRAL & SOUTHERN ROCKIES
DAYS 2-3...
TWO DISTINCT MID-LEVEL IMPULSES WILL INTERACT AS THEY MOVE ACROSS
THE GREAT BASIN AND INTO THE CENTRAL ROCKIES TO BRING HEAVY SNOW TO
THE HIGHER ELEVATIONS OF CO AND NM. DURING THE PAST FEW MODEL RUNS
THE TRENDS HAVE BEEN FOR MORE SUBSTANTIAL SNOW BUT WITH A FARTHER
SOUTH FOOTPRINT, WITH SIGNIFICANT ACCUMULATIONS NOW EXPECTED TO
MISS WYOMING, BUT AFFECT COLORADO AND NEW MEXICO WEDNESDAY NIGHT
THROUGH FRIDAY NIGHT.
AT THE BEGINNING OF THE PERIOD /00Z WEDNESDAY/ THESE IMPULSES WILL
BE POSITIONED OVER CA, AND WEST OF BAJA, RESPECTIVELY. THROUGHOUT
D1, THE LEAD IMPULSE OVER CA WILL OPEN AND BECOME EMBEDDED IN THE
LARGER TROUGH OVER THE GREAT BASIN, WHILE THE STRONGER IMPULSE
(REALLY A CUTOFF LOW) WILL HANG BACK AND MOVE LITTLE UNTIL OPENING
ON THURSDAY AS IT DRIFTS EASTWARD OVER BAJA. AS THIS SECONDARY
EVOLUTION OCCURS, THE RESULT WILL BE A LONGWAVE POSITIVELY TILTED
TROUGH ANCHORED NE TO SW ACROSS THE CENTRAL AND SOUTHERN ROCKIES,
WITH 500MB HEIGHTS FALLING BELOW THE 10TH PERCENTILE WITHIN THE
CFSR DATABASE ACROSS THE DESERT SOUTHWEST. THIS EVOLUTION WILL
RESULT IN BROAD HEIGHT FALLS AND THE AMPLIFICATION OF AN
IMPRESSIVE SUBTROPICAL JET STREAK ARCHING FROM THE FOUR CORNERS
INTO THE OHIO VALLEY. WHERE THE LFQ OF THIS JET STREAK OVERLAPS
WITH THE HEIGHT FALLS, BROAD SYNOPTIC LIFT WILL OCCUR, LIKELY
FOCUSED OVER CO AND NM.
AT THE SAME TIME, SINCE THE PRIMARY TROUGH AXIS WILL LAG TO THE
WEST DURING THIS FORECAST PERIOD, PERSISTENT SW FLOW WITHIN THE
700-500MB LAYER WILL TRANSPORT MOISTURE NORTHEASTWARD, AND WHILE
THE CORE OF THE IVT WILL REMAIN SOUTH OF THE FOUR CORNERS, THERE
WILL BE SUFFICIENT MOISTURE TO RESULT IN HEAVY PRECIPITATION.
THE HEAVIEST PRECIPITATION IS LIKELY IN THE UPSLOPE REGIONS OF THE
EAST-FACING TERRAIN THANKS TO EASTERLY FLOW BEHIND A COLD FRONT,
BUT MODEST FGEN AND CONTINUED MID-LEVEL ISENTROPIC ASCENT WILL ALSO
EXPAND PRECIPITATION ACROSS MUCH OF CO AND NM BY 00Z-06Z FRIDAY.
SNOW LEVELS THROUGH THE EVENT WILL REMAIN ELEVATED, GENERALLY
AROUND 8000 FT, BUT MAY PERIODICALLY FALL TO 7000 FT THROUGH A
COMBINATION OF PRECIPITATION LOADING/DYNAMIC COOLING, LOWERING
HEIGHTS ALOFT, AND CAA BEHIND THE COLD FRONT. THIS WILL ALLOW FOR
SOME LIGHT ACCUMULATIONS EVEN OUT ONTO THE PALMER DIVIDE AND RATON
MESA. HOWEVER, THE HEAVIEST SNOWFALL IS LIKELY IN THE HIGHER
ELEVATIONS ALONG THE FRONT RANGE, SANGRE DE CRISTOS, AND AS FAR
WEST AS THE SAN JUANS. 2-DAY WPC PROBABILITIES ARE HIGH FOR MORE
THAN 12 INCHES OF SNOW ARE HIGH (>70%) IN THE HIGHER ELEVATIONS OF
THE FRONT RANGE, INCLUDING THE PIKE'S PEAK REGION, AND ALONG THE
SANGRE DE CRISTOS. LOWER ELEVATIONS WILL HAVE LESS SNOW, BUT I-25
WILL ALSO LIKELY EXPERIENCE SOME MODEST ACCUMULATIONS WHERE IT
CROSSES THE PALMER DIVIDE AND RATON MESA AS REFLECTED BY WPC
PROBABILITIES FOR 4+ INCHES IN THESE AREAS THAT RISE TO 30-50%.
THE PROBABILITY FOR SIGNIFICANT ICING OVER ONE-TENTH OF AN INCH IS
LESS THAN 10 PERCENT.
WEISS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page