Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 030935
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
435 AM EST SAT DEC 03 2016

VALID 12Z SAT DEC 03 2016 - 12Z TUE DEC 06 2016


DAYS 1-3...

...PACIFIC NORTHWEST/NORTHERN ROCKIES...

A SHORTWAVE TROUGH AND ITS ASSOCIATED COLD FRONT ARE EXPECTED TO
DROP SOUTH INTO THE PACIFIC NORTHWEST SAT NIGHT/SUN
MORNING...USHERING IN THE COLDEST AIR OF THE SEASON THUS FAR.
HEAVY SNOWS ARE EXPECTED ALONG THE FRONT IN THE NORTHERN
CASCADES...WHERE ACCUMULATIONS EXCEEDING A FOOT ARE LIKELY BY
EARLY SUN.  AS THE SHORTWAVE CONTINUES TO DIG TO THE SOUTHEAST AND
SURFACE LOW PRESSURE  DEVELOPS EAST OF THE DIVIDE...HEAVY SNOWS
ARE FORECAST TO SPREAD EAST ACROSS THE NORTHERN ROCKIES...WITH
SEVERAL INCHES LIKELY ACROSS THE RANGES OF NORTHERN AND CENTRAL
ID...NORTHWESTERN MT AND NORTHWESTERN WY SUN INTO EARLY MON.
MEANWHILE BACK TO THE WEST...HEAVY SNOWS ARE EXPECTED TO SHIFT
SOUTH ALONG THE TRAILING FRONT BEFORE TAPERING OFF AS THE FRONT
PUSHES FURTHER TO THE SOUTH INTO THE OREGON CASCADES LATE SUN.  AS
COLD AIR CONTINUES TO SPILL IN BEHIND THE FRONT...SNOW LEVELS WILL
CONTINUE TO DROP TO AROUND 500 FT ACROSS WESTERN WA/OREGON ON MON.
 WITH THE COLD AIR IN PLACE...AN UPSTREAM SHORTWAVE APPROACHING
FROM THE NORTHWEST WILL BRING A RENEWED CHANCE FOR PRECIPITATION
TO THE REGION BY MIDDAY ON MON.

...NORTHERN PLAINS...

THE LEADING SHORTWAVE MOVING ACROSS THE PACIFIC NORTHWEST ON SUN
IS FORECAST TO SWING ACROSS THE NORTHERN PLAINS ON MON...ASSUMING
A NEGATIVE TILT/CLOSED MID LEVEL CENTER AS IT LIFTS ACROSS THE
NORTHERN ND/MN BORDER INTO CANADA MON NIGHT.  LOW/MID LEVEL
FRONTOGENESIS ON THE NORTHWEST SIDE OF THE ASSOCIATED SURFACE LOW
IS EXPECTED TO SUPPORT SNOWS ACROSS NORTHEASTERN ND/NORTHWESTERN
MN...WHERE SOME MODERATE TO LOCALLY HEAVY ACCUMULATIONS ARE
POSSIBLE BEFORE THE SYSTEM LIFTS INTO CANADA TUE MORNING.  THIS
AXIS OF HEAVIER AMOUNTS WILL DEPEND IN LARGE PART ON THE TRACK OF
THE LOW.  UNFORTUNATELY MODELS UP TO THIS POINT HAVE SHOW A GOOD
DEAL OF SPREAD AND POOR RUN-TO-RUN CONSISTENCY AND THEREFORE
FORECAST CONFIDENCE IS LIMITED.  TO ADDRESS THE UNCERTAINTY...THE
WPC FORECAST FOLLOWED A MIDDLE OF THE ROAD SOLUTION REFLECTED BY A
BLEND OF THE LAST FEW GFS/ECMWF/UKMET RUNS.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

PEREIRA

$$





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