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Winter Weather Forecast Discussion
 
(Latest Discussion - Issued 0819Z Oct 22, 2017)
 
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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
419 AM EDT SUN OCT 22 2017

VALID 12Z SUN OCT 22 2017 - 12Z WED OCT 25 2017


DAYS 1 THROUGH 3...

...PACIFIC NORTHWEST/NORTHERN ROCKIES...

DAY 1...

THE LIFT WITH THE SHORT WAVE CROSSES THE NORTHERN ROCKIES TODAY IN
THE MOIST WEST FLOW 850-500 MB. THE COMBINATION OF SYNOPTIC SCALE
LIFT AND UPSLOPE FLOW BEHIND A PACIFIC FRONTAL BOUNDARY WILL
PRODUCE CONTINUING SNOW IN THE HIGHER ELEVATIONS OF
THE WA CASCADES..CONTINUING INLAND TO THE ROCKY MOUNTAIN FRONT
RANGE IN MT...AS WELL AS THE GRAND TETONS.  IN THESE LOCATIONS...
THERE WAS A MODEL SIGNAL FOR LOCALIZED 4 TO 8 INCHES OF SNOWFALL. 
THESE AMOUNTS ARE SUPPORTED MEMBERS OF THE 21Z SREF AND 12Z ECMWF
ENSEMBLES SHOWING 4+ INCHES OF SNOWFALL.  SUNDAY NIGHT INTO MONDAY
LAPSE RATES DECREASE AND DRY AIR AND SINKING MOTION ALOFT DEVELOP
IN RESPONSE TO THE APPROACHING MID LEVEL RIDGE ACROSS THE PACIFIC
NORTHWEST. SNOW COVERAGE/INTENSITY DECREASE AS A RESULT.

DAY 2/3...

THE PROBABILITY OF HEAVY SNOW IS LESS THAN 10 PERCENT.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT DAYS
1-3.

PETERSEN