Quantitative Precipitation Forecast
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000
FOUS11 KWBC 260854
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 AM EST SAT NOV 26 2016

VALID 12Z SAT NOV 26 2016 - 12Z TUE NOV 29 2016

DAY 1 TO 3...

...WESTERN U.S....

A RATHER UNSETTLED WEEKEND INTO MONDAY FOR THE WESTERN STATES...
AS WIDESPREAD MTN SNOW IS EXPECTED. A WALL OF MOISTURE WITH A
SPLIT FLOW UPPER TROUGH WILL MOVE INTO THE WEST COAST ON SAT...
THE SRN STREAM PRESSING THROUGH CA INTO THE DESERT SW AND FOUR
CORNERS REGION... WHILE THE NRN STREAM SHIFTS INTO THE PAC NW
BEFORE SHOWING SIGNS ON POSSIBLY DIGGING IN BEHIND THE SRN STREAM.
EXPECT HEAVY SNOWFALL FROM THE CASCADES TO THE NRN CA MTNS AND
SPINE OF THE SIERRA INTO THE WASATCH AND SAN JUANS OF CO. THE SRN
STREAM FEATURE EJECTS OUT INTO THE PLAINS ON SUN... THE NRN STREAM
UPPER DYNAMICS DIGS INTO THE FOUR CORNERS REGION OR BASE OF THE
UPPER TROUGH... WHILE ANOTHER UPSTREAM DYNAMIC SHORT WAVE TROUGH
SLIDES THE NWRLY COMPONENT INTO THE PAC NW. THE RESULTANT WILL BE
WIDESPREAD HEAVY SNOWFALL ACROSS THE WESTERN STATES FROM THE NW TO
THE FOUR CORNERS REGION. FINALLY ON MON... THE DYNAMICS ARRIVING
INTO THE FOUR CORNERS ON SUN WILL EJECT OUT INTO THE PLAINS...
WHILE THE ARRIVING INTO THE NW WILL DIG SOUTH AND EAST TOWARD THE
SRN ROCKIES. EXPECT HEAVY SNOW ONCE AGAIN FROM THE CASCADES INTO
THE INTER-MOUNTAIN WEST AND CENTRAL/SRN ROCKIES.

...NORTHERN PLAINS/UPPER MIDWEST...

A SIGNIFICANT SNOWSTORM IS EXPECTED SUN AND MON ACROSS THE NRN
PLAINS/UPPER MIDWEST. A SRN STREAM DYNAMIC SHORT WAVE TROUGH
MOVING INTO CA AND THE FOUR CORNERS REGION TODAY WILL EJECT OUT
INTO THE PLAINS COME SUNDAY. THIS SHORT WAVE WILL INDUCE A SURFACE
LOW OVER CENTRAL NE AND THIS CIRCULATION WILL GO THROUGH A RAPID
CYCLE OF SURFACE CYCLOGENESIS ACROSS THE DAKOTAS. THE MOISTURE
ADVECTION AHEAD OF THE SYSTEM WILL EVENTUALLY WRAP AROUND THE AREA
OF LOW PRESSURE ALLOWING A SOLID DEFORMATION ZONE/COMMA HEAD TO
FORM WITH STRONG DYNAMIC COOLING ON THE BACKSIDE OF THE SYSTEM.
THE EXPECTED ZONE OF HEAVY SNOWFALL APPEARS LIKELY FROM CENTRAL SD
INTO WEST AND CENTRAL ND STARTING LATE SUN THROUGH MON... AS THE
CIRCULATION BECOMES STACKED AND RELATIVELY STATIONARY. WPC
FOLLOWED A COMPROMISE BETWEEN THE LATEST GFS/ECMWF FOR HEAVY SNOW
PROBS... DESPITE SOME SPREAD IN THE MASS FIELDS AND QPF... THE
PTYPE OF EACH GLOBAL MODEL IS ALMOST IDENTICAL.

...MAINE...

A SHORT WAVE ROUNDING THE BASE OF A MODERATELY AMPLIFIED UPPER
TROUGH OVER THE NERN QUAD OF THE COUNTRY WILL INDUCE A SURFACE LOW
OFFSHORE OF THE NORTHEAST. THIS LOW WILL INTENSIFY RAPIDLY WHILE
LIFTING NORTHWARD BEFORE SHIFTING OR RETROGRADING MORE NORTHWEST
OVER TIME. THE MORE NWRLY TRAJECTORY IS FROM THE INFLUENCE OF A
CLOSED MID TO UPPER LOW OVER QUEBEC AND NEG TILT TO THE UPPER
TROUGH AXIS. NEEDLESS TO SAY... DESPITE THE BULK OF THE SENSIBLE
WEATHER OCCURRING OFFSHORE FROM NEW ENGLAND... ENOUGH ATLANTIC
MOISTURE WILL FEED ALONG A RELATIVELY NARROW AXIS OR INVERTED
TROUGH AXIS INTO MAINE. EXPECT MODERATE TO LOCALLY HEAVY SNOW
ACROSS NRN MAINE ON SAT BEFORE DISSIPATING ON SUN WITH THE UPPER
LOW WEAKENING.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

MUSHER

$$





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