Quantitative Precipitation Forecast
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FOUS11 KWBC 242059
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
458 PM EDT FRI APR 24 2015

VALID 00Z SAT APR 25 2015 - 00Z TUE APR 28 2015


DAYS 1 TO 3...

...NORTHERN NEW ENGLAND...

COLD CYCLONIC FLOW WITH HIGH RH WILL LINGER OVER PARTS OF THE
NORTHEAST UNITED STATES TONIGHT INTO SATURDAY MORNING.  BETWEEN
THE SYNOPTIC SCAL FORCING AND OROGRAPHIC LIFT BEING FORCED AT LOW
LEVELS...LIGHT SNOW SHOULD CONTINUE TO FALL IN THE NORTH AND WEST
ASPECTS OF THE WESTERN ME MOUNTAINS AND THE NORTHERN NEW HAMPSHIRE
MOUNTAINS.  SNOWFALL AMOUNTS ON THE ORDER OF 1 TO 3 INCHES ARE
EXPECTED...ALTHOUGH THERE WAS ENOUGH SUPPORT TO WARRANT A SLIGHT
RISK OF 4 INCHES OF SNOW ARE POSSIBLE NEAR THE BOUNDARY MOUNTAINS
OF MAINE TONIGHT.  AFTER THAT...THE DEEPEST MOSITURE SHOULD MOVE
OFF SHORE AND THE THREAT OF AN ADDITIONAL 4 OR MORE INCHES OF SNOW
DECREASES.


...PACIFIC NORTHWEST/NORTHERN AND CENTRAL ROCKIES/GREAT BASIN...

A RATHER UNSETTLED PERIOD FOR A LARGE PORTION OF THE WESTERN
UNITED STATES THROUGH THE UPCOMING WEEKEND WHICH INCLUDES THE
THREAT FOR HEAVY MTN SNOW.

A LARGE CLOSED MID TO UPPER LOW NEAR VANCOUVER ISLAND EARLY THIS
AFTERNOON WILL CONTINUE TO DRIFT SLOWLY TO THE SOUTH AND EAST
ACROSS WA OVER THE NEXT 24 HOURS.  HEIGHT FALLS WILL PRECEDE THIS
LOW THROUGH THE NORTHERN AND CENTRAL PORTIONS OF THE INTERMOUNTAIN
WEST AND EVENTUALLY ACROSS THE ROCKIES...USHERING IN A SHARPLY
COLDER AIRMASS.  THE RESULT WILL BE AN INCREASING AREA OF SNOW
FROM THE COASTAL RANGES...NORTHERN ROCKIES AND PARTS OF THE
INTERMOUNTAIN WEST TONIGHT INTO SATURDAY.  THE AREA WILL CONTINUE
TO PUSH SOUTH AND EAST SUNDAY AND MONDAY...FINALLY CROSSING THE
CENTRAL ROCKIES BY LATE MONDAY/EARLY TUESDAY.

BEST SNOWFALL SHOULD OCCUR ON SAT AND SUNDAY DESPITE THE UPPER LOW
BEGINNING TO FILL.  THE WEAKENING DYNAMICS WOULD BE OFFSET BY A
VERY DYNAMIC JET STREAK AND BATCH OF UPPER DYNAMICS WHICH DIGS
THROUGH NRN CA INTO THE WRN PORTION OF THE FOUR CORNERS REGION.

WPC USED THE  FAVORED A BLEND OF THE GFS/NAM/ECMWF FOR THERMAL
PROFILES ON 4 AND 8 INCH HEAVY SNOW PROBS... ESPECIALLY INTO THE
UT UINTAS AND SRN ABSAROKA TO THE WIND RIVER RANGE IN WY.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

BANN


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