Quantitative Precipitation Forecast
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000
FOUS11 KWBC 220844
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
344 AM EST MON JAN 22 2018

VALID 12Z MON JAN 22 2018 - 12Z THU JAN 25 2018


...CENTRAL PLAINS AND UPPER MS VALLEY INTO GREAT LAKES/NORTHERN
NEW ENGLAND...

A MAJOR WINTER STORM WITH BLIZZARD CONDITIONS AND EXTREMELY HEAVY
SNOWFALL WILL INUNDATE PARTS OF NEBRASKA, IOWA, MINNESOTA AND
WISCONSIN ON MONDAY.

A PRONOUNCED SOUTHERN STREAM TROUGH IS LOCATED OVER THE CENTRAL
PLAINS/MID MS VALLEY EARLY THIS MORNING. THIS INTENSE STORM SYSTEM
FEATURING A LARGE BUT COMPACT CLOSED 500MB LOW CENTER AND
DEEPENING SURFACE LOW WILL GRADUALLY PRESS OFF DOWNSTREAM TO THE
NORTH AND EAST. THE 500MB LOW CENTER SHOULD TRANSITION FROM KS TO
LOWER MI/NORTHERN IN, WHILE THE INTENSIFYING SURFACE LOW SLIDES
FROM SWRN IA/NWRN MO TO SERN IA/NERN MO WITH A POSSIBLE TRIPLE
POINT/SECONDARY AREA OF LOW PRESSURE FORMS OVER NORTHERN IL MON
EVENING. THE WINTER CYCLONE CONTINUES TO CAPITALIZE ON ANOMALOUS
MOISTURE CONTENT FROM THE GULF OF MEXICO FOR A VARIETY OF PTYPES.
THE OVERNIGHT GUIDANCE SHOWS VERY SMALL SPREAD WITH MASS FIELDS
AND CONVERGING MODEL SOLUTIONS PROVIDED CONFIDENCE ON CRITICAL
THERMALS. IN FACT, WPC WAS ABLE TO USE A MULTI-MODEL CONSENSUS FOR
PTYPE. THE NWRN SECTION OF THE STORM SYSTEM WILL LIKELY SEE A
FLOURISHING DEFORMATION ZONE AND COMMA HEAD OF INTENSE BANDING
SNOW LINGER FROM NERN NE/NWRN IA/SERN MN THROUGH NORTH CENTRAL WI
INTO THE UP OF MI. THIS AXIS WILL LIKELY B EXTREMELY NARROW AND
APPEARS MORE THAN LIKELY TO INCLUDE THE MSP/STP METRO AREA IN A
HIGH END EVENT. THE ICING COULD BE A CONSIDERABLE PROBLEM FROM
EAST CENTRAL WI AND NORTHERN LOWER MI INTO SERN ONTARIO AND
SPILLING INTO PARTS OF NEW ENGLAND, AS THE SHALLOW COLD AIR MASS
HAS DIFFICULTY ERODING.

THEN ON TUES, THE POWERFUL BUT PROGRESSIVE WINTER STORM WILL SWEEP
UP INTO AND THROUGH THE NERN QUAD OF THE COUNTRY, WITH THE MAIN
SURFACE LOW MOVING INTO SOUTHERN QUEBEC GRADUALLY GIVING WAY TO A
TRIPLE POINT LOW OVER NOVA SCOTIA BY WEDNESDAY MORNING. THE BULK
OF THE HEAVY SNOW WILL IMPACT QUEBEC BUT MAY CLIP NORTHERN MAINE,
WHILE DEVELOPING CYCLONIC FLOW ON THE BACKSIDE OF THE SYSTEM COULD
START LAKE EFFECT SNOW DOWNWIND OF THE GREAT LAKES.

...NORTHWEST/CA INTO NORTHERN INTER-MOUNTAIN WEST...

AN EVOLVING UPPER VORTEX AND TROUGH NEAR THE GULF OF AK/NERN PAC
WILL STEER A RATHER POTENT SHORT WAVE TROUGH WITH A TREMENDOUS
FETCH OF SWRLY UPPER DIFLUENT FLOW AND PAC MOISTURE TRANSPORT INTO
THE NW ON TUES. SNOW LEVELS MAY INCREASE WITH THIS TYPE OF SYSTEM
ARRIVING INTO THE PAC NW BUT HEAVY OROGRAPHIC SNOW IS ANTICIPATED
FOR THE WA/OR CASCADES INTO THE BLUE MTNS AND NORTHERN
BITTERROOTS. THEN ON WED, THE ENTIRE LARGE SCALE TROUGH OVER THE
EASTERN PAC MOVES INLAND ACROSS THE WEST WITH CRASHING UPPER
HEIGHTS AND A RATHER ACTIVE UPPER-LEVEL JET. THIS SHOULD RESULT IN
WIDESPREAD HEAVY SNOWFALL FOR THE WA/OR CASCADES INTO THE NORTHERN
CA MTNS AND ENTIRE SPINE OF THE SIERRA AND SPREAD INTO THE
INTER-MOUNTAIN WEST FAVORED TERRAIN OF THE BLUE
MTNS/SAWTOOTH/BITTERROOTS AND NORTHERN ROCKIES.

MUSHER




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