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Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0617Z May 02, 2018)
 
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Abbreviations and acronyms used in this product
 
Geographic Boundaries -  Map 1: Color  Black/White       Map 2: Color  Black/White


PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
217 AM EDT WED MAY 2 2018

VALID 12Z WED MAY 2 2018 - 12Z SAT MAY 5 2018


DAYS 1 THROUGH 3...

THE FORECAST PERIOD WILL BEGIN ON WEDNESDAY MORNING WITH A
VERTICALLY STACKED CLOSED LOW CENTERED OVER THE LAS VEGAS AREA
THAT IS EXPECTED TO EVOLVE INTO A POSITIVELY TILTED LONG WAVE
TROUGH BY THURSDAY MORNING.  THIS WILL PLACE THE MOUNTAINS OF
EASTERN UTAH AND CENTRAL COLORADO UNDER THE FAVORABLE LEFT EXIT
REGION OF THE UPPER LEVEL JET.  THIS TROUGH AXIS THEN EXITS ACROSS
THE NORTHERN AND CENTRAL PLAINS BY THURSDAY NIGHT AND FORCING FOR
ASCENT WANES BY THE END OF DAY 2 OVER THIS REGION.  SURFACE
CYCLOGENESIS IS FORECAST TO ENSUE OWING TO DIVERGENCE ALOFT FROM
THE UPPER TROUGH OVER EASTERN COLORADO, AND STEADY UPSLOPE FLOW IN
THE BOUNDARY LAYER NORTH OF THE SURFACE LOW WILL ADVECT LOW LEVEL
MOISTURE TOWARDS THE FRONT RANGE. 

MODERATE TO HEAVY SNOWFALL IS EXPECTED FOR PORTIONS OF THE WASATCH
AND UINTA RANGES IN UTAH, AND ALSO THE SAN JUAN MOUNTAINS AND
NORTH CENTRAL COLORADO/SOUTH CENTRAL WYOMING ROCKIES AS FREEZING
LEVELS LOWER BEHIND THE FRONT.  THE COMBINATION OF MOISTURE IN THE
UPSLOPE FLOW AND MARGINAL INSTABILITY OWING TO STEEPENING LAPSE
RATES IS EXPECTED TO PRODUCE A MAXIMUM AREA OF 8 TO 12 INCHES OF
SNOWFALL, PRIMARILY CENTERED ON THE NORTHERN COLORADO FRONT RANGE.
 THERE WAS GOOD MODEL AGREEMENT WITH THE TIMING AND PLACEMENT OF
THE SYNOPTIC SCALE FEATURES, SO THE THERMAL PORTION OF THE
FORECAST WAS BASED ON A BLEND OF THE 00Z GFS/NAM AND 12Z ECMWF.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT
NATIONWIDE.

D. HAMRICK