Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 282058
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EST FRI NOV 28 2014

VALID 00Z SAT NOV 29 2014 - 00Z TUE DEC 02 2014

DAYS 1 TO 3...

...PACIFIC NORTHWEST/NORTHERN ROCKIES/NORTHERN PLAINS/UPPER
MIDWEST...

LITTLE HAS CHANGED WITH THE FORECAST FOR THE NEXT 3 DAYS IN THE
BIG PICTURE. HEIGHT FALLS IN BOTH THE SOUTHERN AND NORTHERN STREAM
WILL CARVE OUT A TROF OVER WESTERN NORTH AMERICA.  IN ADDITION...A
COMPACT SHORTWAVE TROUGH EMBEDDED WITHIN THE NORTHERN STREAM
SHOULD DROP SOUTH AND EAST FROM BRITISH COLUMBIA WILL MOVE ACROSS
THE NORTHWEST PORTION OF THE COUNTRY...CREATING THE POTENTIAL FOR
HEAVY SNOW IN THE NORTHWEST MOUNTAINS.

THE GREATEST RISK FOR HEAVY SNOW SHOULD BE FROM LATER TONIGHT
THOUGH THE DAY ON SATURDAY ACROSS THE NORTHERN ROCKIES WHERE 1 TO
2 FEET OF SNOW ARE POSSIBLE IN NORTHWEST MONTANA.  A COMBINATION
OF ENHANCED UPSLOPE FLOW OF A COLD AND NEARLY SATURATED AIRMASS IN
ROUGHLY CO-LOCATED WITH UPPER LEVEL DIVERGENCE IN THE RIGHT
ENTRANCE REGION OF A 120 TO 140 KT UPPER LEVEL JET.  THE PRIMARY
UNCERTAINTY REMAINS IN THE RANGES FURTHER WEST AS WARM AIR FROM
THE PACIFIC MOVES ONSHORE AND INLAND...KEEPING SNOW ELEVATIONS
HIGH AND LIMITING SNOW AMOUNTS IN THE LOWER ELEVATIONS OF THE
OREGON CASCADES.

THE RISK OF SNOW BUILDS SOUTH ON SATURDAY AS MID LEVEL TROF
AMPLIFIES...WITH THE POTENTIAL FOR HEAVY SNOW REACHING THE
NORTHERN SIERRA NEVADA MOUNTAINS FROM SATURDAY INTO SUNDAY
EVENING.

HOWEVER...CONDITIONS BECOME LESS FAVORABLE FOR HEAVY SNOW ACROSS
THE WESTERN STATES ON DAY 3 AS DRIER AIR BUILDS INTO THE MINUS 12
TO MINUS 18 DEG C LAYER.

THE PROBABILITY FOR SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

BANN

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