Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS11 KWBC 152011
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
411 PM EDT FRI MAY 15 2015

VALID 00Z SAT MAY 16 2015 - 00Z TUE MAY 19 2015

DAYS 1 TO 3...

...WESTERN TERRAIN AND NORTHERN PLAINS...

A DEEP CLOSED UPPER LOW IS BEGINNING TO MOVE INTO THE WESTERN FOUR
CORNERS REGION THIS AFTN WITH A DYNAMIC SHORT WAVE TROUGH MOVING
THROUGH SRN CA. MEANWHILE DOWNSTREAM... ANOTHER POTENT SHORT WAVE
TROUGH IS LIFTING UP THROUGH CO TO WY AND IS EXPECTED TO DEEPEN
RAPIDLY OVER THE NEXT 24 HRS. THUS HEAVY SNOWFALL IS ANTICIPATED
IN TWO SPOTS ACROSS THE WEST ON FRI NIGHT AND SAT. EXPECT PRIME
SRLY TO SWRLY UPPER DIFLUENT FLOW TO IMPACT PARTS OF THE EASTERN
MOGOLLON RIM OF AZ AND SWRN/CENTRAL CO INCLUDING THE SAN JUANS.
THEN OVER NORTHERN TETONS AND ABSAROKA RANGES... EXPECT INTENSE
DYNAMIC COOLING NEAR THE 500-700MB LOW WITH UPSLOPE ENHANCED HEAVY
SNOWFALL.

THE INTENSIFYING SHORT WAVE IN THE BASE OF THE LARGE CLOSED LOW
WILL EJECT OUT OF THE FOUR CORNERS REGION SAT NIGHT AND DEEPEN ON
SUN WHILE INDUCING A SURFACE CIRCULATION OVER SD. THIS SURFACE
FEATURE BECOMING A STACKED LOW WILL TRACK TO ERN ND/NWRN MN. THE
HEAVY SNOWFALL PERSISTING OVER THE NRN ROCKIES TO ABSAROKAS/BIG
HORNS WILL GRADUALLY SUBSIDE DURING THE 24 HR PERIOD... WHILE
INTENSE COOLING ALOFT ON THE NW QUAD OF THE LOW COULD CONVERT
STEADY MDT TO HEAVY RAINFALL AND THERMAL PROFILES OVER TO A
MIXTURE OF SNOW OR EVEN ALL SNOW. THIS REMAINS A BIT UNCERTAIN
ESPECIALLY GIVEN THE TIME OF YEAR AND SLIGHT SPREAD OF THE
GUIDANCE BUT WPC KEPT A LOW PROB OF 4 INCHES ACROSS NRN ND.

THEN FINALLY SUN EVENING INTO MON... THE SYSTEM WILL SLOWLY TRACK
OFF TO THE NORTH AND EAST AND KEEP A SLIGHT THREAT FOR SNOW/SNOW
MIXTURE ON THE TAIL END OF THE DEFORMATION REGION FROM NERN ND
INTO NWRN MN. THIS IS WHERE A LOW PROB OF 4 INCHES WAS BASICALLY
PLACED. ALSO UPSTREAM... THE NEXT 700 MB TROUGH... LOWERING OF
UPPER HEIGHTS AND FRONT MAY DRIVE ANOTHER HEAVY SNOW FOR THE
CENTRAL CA SIERRA.

THE PROBABILITY OF SIGNIFICANT ICING IS LESS THAN 10 PERCENT.

MUSHER


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