Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 222023
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 PM EST SUN JAN 22 2017

VALID 00Z MON JAN 23 2017 - 00Z THU JAN 26 2017

DAYS 1-3...

...WEST INTO UPPER MIDWEST/UPPER MS VALLEY AND GREAT LAKES....

A VERY WRAPPED UP LOW PRESSURE SYSTEM OFF THE WEST COAST IS
DRIVING A STRONG UPPER JET INTO NRN CA THIS MORNING. WATER VAPOR
IMAGERY DEPICTS A LARGE LOW PRESSURE SYSTEM OFF THE PAC NW
COAST... TREMENDOUS COLD AIR ALOFT SWEEPING IN FROM THE ERN PAC
AND A LONG FETCH OF PAC AND SUBTROPICAL MOISTURE TRANSPORTING FROM
NEAR HAWAII INTO CENTRAL CA. EVEN THOUGH THIS IS THE LAST IN A
SERIES OF POWERFUL WEATHER SYSTEMS FROM THE PAC...  EXTREMELY
HEAVY SNOW WILL PUMMEL THE TERRAIN OF CA TODAY AND TMRW AND LINGER
INTO TUES.

THE FOCUS ON SUN EVENING THROUGH MON IS REALLY FROM THE SOUTHERN
SIERRA AND SOUTHERN CA TO THE INTER-MOUNTAIN WEST... THOUGH
ONSHORE FLOW WILL REMAIN INTACT ACROSS ALL OF CA. THE VERY ACTIVE
JET WITH EXTREMELY FAVORABLE LEFT EXIT REGION UPPER DYNAMICS AND
PHASED MOISTURE TRANSPORT WILL POUND THE CENTRAL/SRN SIERRA WITH
ANOTHER 1 TO 2 FEET... AFFECT THE SOUTHERN CA MTNS OF THE SAN
GABRIEL/SAN BERNADINO AND REALLY IMPACT THE INTERIOR TERRAIN WITH
DIFLUENT SWRLY FLOW ALOFT. A FOOT OR MORE WILL BE POSSIBLE ACROSS
PARTS OF THE WASATCH/TETONS AND CO ROCKIES.

BY MON EVENING THROUGH WED... THE ENTIRE STORM SYSTEM EMERGES FROM
THE CENTRAL ROCKIES... BEGINS TO EJECT OUT INTO THE CENTRAL PLAINS
AND ALLOWS A DEVELOPING AREA OF SURFACE LOW PRESSURE TO GO THROUGH
CYCLOGENESIS FROM THE CENTRAL PLAINS TO THE GREAT LAKES. A DECENT
AMOUNT OF SPREAD EXISTS AT THE MOMENT BUT THE OVERALL CONSENSUS IS
A STREAK OF HEAVY OVERRUNNING AND DYNAMIC COOLING SNOW. WPC
FOLLOWED A COMPROMISE AT THE MOMENT OF THE GFS/ECMWF WITH MORE
ECMWF FOR AN AXIS OF ACCUMULATING SNOW FROM WY THROUGH SD/NRN NE
INTO THE UPPER MS VALLEY.


...INTERIOR NORTHEAST AND NEW ENGLAND...

A LARGE AND VERY ACTIVE SOUTHERN STREAM SYSTEM ACROSS THE SOUTHERN
TIER OF THE COUNTRY TODAY... PRODUCING HEAVY RAIN AND SEVERE
WEATHER... WILL SHIFT TOWARD THE MID ATLANTIC STATES ON MON...
WHILE AN IMPRESSIVE BLOCKING RIDGE OF HIGH PRESSURE TO THE NORTH
WILL LOCK IN LOW LEVEL COLD AIR OVER NERN SECTION OF THE COUNTRY.
THUS ATLANTIC AND GULF MOISTURE ADVECTING INLAND AROUND THE
CIRCULATION AND ON THE NOSE OF THE LOW LEVEL JET SHOULD YIELD A
THREAT OF SNOW ACROSS NRN PA AND WRN NY. THE MID TO UPPER LOW WILL
BEGIN TO PHASE WITH THE NRN STREAM ON TUES AND THE ENTIRE UPPER
TROUGH WILL NEG TILT. A DEVELOPING AND INTENSIFYING AREA OF
SURFACE LOW PRESSURE WILL GRADUALLY LIFT NORTHWARD ALONG THE NERN
SEABOARD. ONCE AGAIN... OVERALL MINIMAL SPREAD BETWEEN THE
GFS/ECMWF INDICATES A VARIETY OF WINTRY PRECIP OF
SNOW/SLEET/FREEZING RAIN ACROSS THE INTERIOR NORTHEAST AND MUCH OF
NEW ENGLAND WITH THE LARGEST SNOW ACCUMULATIONS OCCURRING FROM
CENTRAL/UPSTATE NY INTO SOUTHERN QUEBEC. BY WED... THE ENTIRE
STORM SYSTEM WILL LIFT UP INTO THE CANADIAN MARITIMES.


MUSHER

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