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Winter Weather Forecast Discussion
 
(Caution: Version displayed is not the latest version. - Issued 0728Z May 11, 2014)
 
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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
328 AM EDT SUN MAY 11 2014

VALID 12Z SUN MAY 11 2014 - 12Z WED MAY 14 2014

...DAYS 1 TO 3...

...ROCKIES/ADJACENT HIGH PLAINS...

MAJOR WINTER STORM AFFECTING THE CENTRAL ROCKIES THROUGH MONDAY.

OTHER THAN THE 00Z NAM WHICH BECOMES SUSPICIOUSLY DEEP CROSSING
THE ROCKIES AND THUS HEAVIER WITH THE SNOW AND COLDER WITH
TEMPERATURES INTO THE ADJACENT HIGH PLAINS...AND THE 21Z SREF
WHICH MIRRORS MANY ASPECTS OF THE HEAVIER AND COLDER NAM...00Z
GUIDANCE IS REASONABLY WELL CLUSTERED WITH THE TRACK AND DEPTH OF
THE LOW CROSSING THE ROCKIES.  PREFERRED AN ARRAY OF GUIDANCE THAT
ENCOMPASSES THE PREFERRED SIDE OF THE SOLUTION ENVELOPE THAT
INCLUDES THE GFS/ECMWF/CANADIAN/ECMWF ENSEMBLE MEAN DAY
1...GFS/ECMWF/UKMET/GEFS MEAN DAY 2...AND GFS/GEFS MEAN/ECMWF
DAY3...WITH NO NAM OR SREF USED. 

THE RESULT IS HIGH PROBABILITIES OF A FOOT OR MORE OF SNOW FOR
NORTHERN PORTIONS OF THE CENTRAL ROCKIES INCLUDING THE LARAMIE
MOUNTAINS THROUGH SUNDAY NIGHT...
WITH MODERATE PROBABILITIES OF 12 INCHES EXTENDING SOUTHWARD INTO
THE SAN JUANS AND SANGRE DE CRISTO RANGES ON MONDAY AS THE BASE OF
THE LOW MOVES OVERHEAD.  LOW TO MODERATE PROBABILITIES OF 4 AND 8
INCHES OF SNOW INCLUDE MOST AREAS ABOVE 4 TO 5 THOUSAND FEET
INCLUDING THE WASATCH RANGES/TETONS/BIG HORNS/BLACK HILLS.  SOME
PARTS OF THE FRONT RANGE IN COLORADO COULD RECEIVE UPWARDS OF 2
FEET OR MORE...
PARTICULARLY ELEVATIONS ABOVE 8 THOUSAND FEET. 

THE FINAL PROBABILITIES FOR HEAVY SNOW WERE ADJUSTED SLIGHTLY
WESTWARD ACROSS THE HIGH PLAINS FROM THE PRIOR ISSUANCE TO REFLECT
A PREFERENCE FOR SNOW REMAINING LARGELY CONFINED TO THE HIGHER
ELEVATIONS AS INDICATED BY THE GFS/ECMWF SOLUTIONS THAT ARE WARMER
THAN THE NAM/SREF.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT FOR
ALL 3 DAYS.

JAMES