Quantitative Precipitation Forecast
Issued by NWS

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FOUS11 KWBC 210738
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
238 AM EST SAT JAN 21 2017

VALID 12Z SAT JAN 21 2017 - 12Z TUE JAN 24 2017

DAYS 1-3...

...WESTERN U.S....

THE LAST IN A SERIES OF POWERFUL WEATHER SYSTEMS THAT HAVE BROUGHT
AND WILL CONTINUE TO BRING EXCESSIVE SNOWFALL IN FORMERLY PARCHED
CENTRAL AND NORTHERN CALIFORNIA WILL AGAIN PRODUCE SNOWFALL
AMOUNTS OF SEVERAL FEET OVER THE NEXT 3 DAYS.  HOWEVER...THE END
OF THE 3 DAY FORECAST WILL FINALLY SEE THE END OF THE RECENT
ONSLAUGHT OF WESTERN STORMS THAT HAS BEEN A HUGE STORY IN
RESTORING WESTERN SNOWPACK AND AT LEAST PARTIALLY ALLEVIATING THE
LONGSTANDING DROUGHT.

ON SATURDAY INTO SUNDAY MORNING/DAY 1...THE STRONG PACIFIC SYSTEM
NOW AFFECTING THE WEST COAST WILL CONTINUE EASTWARD ACROSS THE
INTERMOUNTAIN WEST INTO THE SOUTHWEST WITH SOME OF THE HEAVY SNOWS
CONTINUING TO FALL ACROSS MUCH OF THE SIERRA WITH MODERATE TO HIGH
PROBABILITIES OF GREATER THAN A FOOT OF SNOW AS WELL AS ACROSS THE
MOUNTAINS OF NORTHERN CALIFORNIA.  SIGNIFICANT SNOW ON THE ORDER
OF 4 TO 8 INCHES IN GENERAL WILL BE ALSO FOUND ACROSS THE WASATCH
IN UTAH...ACROSS MUCH OF WESTERN COLORADO AND ACROSS THE MOGOLLON
RIM IN CENTRAL AND EASTERN ARIZONA.

THE NEXT AND FINAL SERIES OF CYCLONES WILL AGAIN PRODUCE A HUGE
INFLUX OF MOISTURE AS WELL AS A SIGNIFICANT CYCLONE ACROSS THE
WEST COAST...AGAIN FOCUSING MUCH OF THE WINTER WEATHER IMPACTS
ACROSS THE SIERRA WHERE 1 TO GREATER THAN 3 FEET OF SNOW IS LIKELY
ON DAY 2/SUNDAY INTO MONDAY MORNING. MUCH OF THE WEST WILL SEE
SIGNIFICANT SNOW ON DAY 2...ESPECIALLY ACROSS NEVADA AND ACROSS
THE MOUNTAINS OF SOUTHERN CALIFORNIA WITH MUCH OF NEVADA EXCEPT
THE EXTREME SOUTH IN FOR WIDESPREAD SIGNIFICANT SNOW.  HEAVY SNOW
WILL ALSO FALL ACROSS THE WASATCH AND ACROSS THE MOUNTAINS OF
WESTERN AND CENTRAL COLORADO.

THIS POWERFUL SYSTEM WILL WEAKEN AND BECOME SHUNTED SOUTHWARD
ALONG THE WEST COAST ON DAY 3/MONDAY INTO TUESDAY MORNING.  HEAVY
SNOW WILL FINALLY BEGIN TO TAPER OFF ACROSS THE SIERRA ALTHOUGH AN
ADDITIONAL 4 TO 8 INCHES ARE LIKELY WHILE THE BULK OF THE SNOW
MOVES EASTWARD AS THE LARGE UPPER TROUGH CROSSES THE WESTERN
UNITED STATES WITH WIDESPREAD MOUNTAIN SNOW ACROSS ARIZONA/NEW
MEXICO/COLORADO/UTAH/EASTERN NEVADA/WYOMING AND IDAHO INTO
SOUTHERN NEVADA AND THE DAKOTAS.  HEAVIEST SNOW WILL BE ON THE
ORDER OF 6 TO 12 INCHES WITH HEAVIEST SNOW ACROSS SOUTHWESTERN
COLORADO/UTAH INTO WESTERN WYOMING.  HEAVY SNOW WILL ALSO CONTINUE
ACROSS THE MOGOLLON RIM IN ARIZONA.

DAY 3...

INTERIOR NORTHEAST...

THE SYSTEM CURRENTLY AFFECTING THE WEST COAST WILL SHIFT EASTWARD
ACROSS THE SOUTHERN ROCKIES WITH A CLOSED LOW DEVELOPING OVER THE
SOUTHERN PLAINS BY SATURDAY EVENING/DAY 1.  THIS LOW IS EXPECTED
TO MOVE ACROSS THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST ON
SUNDAY BUT WILL BE ACCOMPANIED BY MILD TEMPERATURES WITH LITTLE OR
NO WINTER WEATHER LIKELY.  AS IT LIFTS NORTHWARD ALONG THE EAST
COAST ON MONDAY...THE SYSTEM WILL BEGIN TO INTERACT WITH COLDER
AIR ASSOCIATED WITH HIGH PRESSURE NORTH OF NEW ENGLAND.   WHILE
THERE ARE DIFFERENCES IN PRECIPITATION AMOUNT AND TYPE TO VARYING
DEGREES...OFFERING A PERIOD OF MIXED PRECIPITATION WITH
ACCUMULATING SNOWS ALONG THE NORTHERN PERIPHERY OF THE
PRECIPITATION SHIELD AS IT REACHES INTO NORTHERN PA...UPSTATE NY
AND CENTRAL TO NORTHERN NEW ENGLAND WILL OCCUR ON MONDAY INTO
MONDAY NIGHT/DAY 3.  FREEZING RAIN/SLEET AND SNOW WILL BE COMMON
FROM NORTHERN PENNSYLVANIA/NEW YORK AND ACROSS INTERIOR NEW
ENGLAND WITH MODERATE CHANCES FOR GREATER THAN 4 INCHES OF SNOW
ESPECIALLY ACROSS PORTIONS OF UPSTATE NEW YORK INTO WEST CENTRAL
NEW ENGLAND.

KOCIN

$$





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