Quantitative Precipitation Forecast
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FOUS11 KWBC 050941
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
441 AM EST MON DEC 05 2016

VALID 12Z MON DEC 05 2016 - 12Z THU DEC 08 2016


DAYS 1-3...

...PACIFIC NORTHWEST...

WITH SNOW LEVELS PLUNGING IN THE WAKE OF A STRONG COLD FRONT THAT
HAS PRESSED WELL SOUTH OF THE REGION...A SHORTWAVE TROUGH EMBEDDED
WITHIN STRONG NORTHWESTERLY FLOW WILL DIVE INTO THE PACIFIC
NORTHWEST...DELIVERING ADDITIONAL PRECIPITATION TO WESTERN
WASH/ORE ON MON.  IN ADDITION TO THE POTENTIAL FOR ADDITIONAL
MODERATE TO HEAVY SNOWS ALONG THE ORE CASCADES...PERHAPS OF MORE
SIGNIFICANT NOTE IS THE THREAT FOR LOWER ELEVATIONS SNOWS ACROSS
WESTERN WASH/ORE.  WITH SNOW LEVELS REMAINING LOW...THERE IS
INCREASING FORECAST CONFIDENCE IN ACCUMULATING SNOWS AT OR NEAR
SEA LEVEL AND ALONG OR JUST ABOVE THE VALLEY FLOORS OF WESTERN
WASH/ORE ON MON.  EXPECT DRYING CONDITIONS ACROSS THE REGION TUE
NIGHT INTO WED AS THE SYSTEM CONTINUES TO DIVE TO THE
SOUTHEAST...REACHING THE GREAT BASIN WHILE A SHORTWAVE RIDGE
BEGINS TO MOVE ACROSS THE NORTHWEST.

...NORTHERN PLAINS/UPPER MIDWEST...

MERGING ENERGY FROM THE NORTHERN U.S. ROCKIES/SOUTHERN CANADA ON
MON IS EXPECTED TO RESULT IN A NEGATIVE TILT TROUGH/MID LEVEL
CENTER DEVELOPING ALONG THE RED RIVER OF THE NORTH MON NIGHT/EARLY
TUE.  IN A REVERSAL OF THE MODEL TRENDS FROM 24-HRS AGO...THE
LATEST GUIDANCE HAS SHIFTED FURTHER SOUTH WITH THE LOW...ONCE
AGAIN REINTRODUCING THE THREAT FOR HEAVY SNOWS ACROSS PORTIONS OF
EASTERN ND AND MN.  ASSUMING NO FURTHER SHIFTS IN THE
GUIDANCE...SEVERAL INCHES OF SNOW MAY BE EXPECTED MON INTO TUE
ACROSS PORTIONS OF N-CENTRAL TO NORTHEASTERN ND AND NORTHWESTERN
MN.

...CENTRAL ROCKIES TO THE LOWER MO VALLEY...

THE PREVIOUSLY NOTED SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST
ON MON IS FORECAST TO MOVE ACROSS THE GREAT BASIN INTO THE CENTRAL
ROCKIES LATE TUE INTO WED...PRODUCING MAINLY LIGHT TO MODERATE
SNOWS ACROSS THE WESTERN CO RANGES.  BY EARLY WED...POST-FRONTAL
UPSLOPE FLOW BOLSTERED A SURFACE WAVE DROPPING SOUTHEAST ACROSS
SOUTHEASTERN CO WILL ENCOURAGE SNOWS ALONG THE FRONT RANGE INTO
THE HIGH PLAINS.  SNOWS ARE EXPECTED TO SHIFT EAST ACROSS
KS/SOUTHERN NEB INTO SOUTHERN IA/NORTHERN MO ON WED WHERE SOME
LIGHT TO MODERATE ACCUMULATIONS CAN BE EXPECTED.

...CENTRAL APPALACHIANS TO THE NORTHEAST...

A REMNANT SHORTWAVE TROUGH ASSOCIATED WITH THE LOW CURRENTLY
MOVING ACROSS NORTHERN MEX IS EXPECTED TO LIFT NORTHEAST THROUGH
THE MID ATLANTIC STATES WITH ON TUE.  AN INITIAL SURFACE MOVING
FROM THE TN/OH VALLEY WILL GIVE WAY TO A LOW DEVELOPING OFF OF THE
NC COAST.  WARM MOIST AIR MOVING ACROSS THE TOP OF COLD AIR
ALREADY IN PLACE IS EXPECTED TO SUPPORT A PERIOD OF MIXED
PRECIPITATION WITH SOME LIGHT ICE ACCUMULATIONS ALONG THE
MOUNTAINS OF EASTERN WV/WESTERN VA/FAR WESTERN MD ON TUE.
EVAPORATIVE COOLING WILL HELP SUPPORT SNOWS FURTHER TO THE NORTH
ACROSS WESTERN/CENTRAL PA INTO CENTRAL NY.  MARGINAL BOUNDARY
LAYER TEMPS AND ISOTHERMAL PROFILES ALOFT MAKE THIS A DIFFICULT
FORECAST...HOWEVER AT LEAST LIGHT SNOW ACCUMULATIONS APPEAR LIKELY
ESPECIALLY ACROSS THE HIGHER TERRAIN OF WESTERN/CENTRAL PA INTO
WESTERN NY AND THE SOUTHERN TIER.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

PEREIRA

$$





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