Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS11 KWBC 192039
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
339 PM EST SUN FEB 19 2017

VALID 00Z MON FEB 20 2017 - 00Z THU FEB 23 2017

DAYS 1 TO 3...

...RANGES OF THE PACIFIC NORTHWEST/CALIFORNIA/GREAT
BASIN/ROCKIES...

AN ACTIVE PERIOD WILL CONTINUE ACROSS THE WEST INTO MID WEEK AS
LONGWAVE TROUGHING BUILDS IN. AN IMPRESSIVE ATMOSPHERIC RIVER WILL
BE FOCUSED INTO CENTRAL CA...BRINGING A LONG DURATION SIGNIFICANT
SNOWFALL TO THE HIGHER ELEVATIONS OF THE CENTRAL AND NORTHERN
SIERRAS TONIGHT INTO THE DAY TUESDAY...WITH THE HEAVIEST RATES
LATE TONIGHT THROUGH MONDAY NIGHT. SEVERAL FEET OF SNOW ARE LIKELY
THROUGH TUESDAY. WHILE AMOUNTS WILL BE LESS...A COUPLE FEET OF
SNOW IS ALSO LIKELY ACROSS THE NORTHERN CA MOUNTAINS IN THE MT
SHASTA VICINITY.

MULTIPLE SHORTWAVES MOVING NORTH OF THE ATMOSPHERIC RIVER WILL
BRING SEVERAL PERIODS OF SNOWFALL TO THE WA AND OR CASCADES INTO
TUESDAY AS WELL...ALTHOUGH AMOUNTS WILL NOT BE AS SIGNIFICANT AS
FURTHER SOUTH. GENERALLY LOOKING AT TOTALS OF 10-20 INCHES
(LOCALLY HIGHER) IN THE FAVORED TERRAIN.

SIGNIFICANT SNOWFALL IS ALSO EXPECTED FURTHER INLAND AS THE
TROUGHING...BROAD SOUTHWEST FLOW AND ANOMALOUS MOISTURE FLUX MOVES
INTO THE NORTHERN GREAT BASIN AND NORTHERN ROCKIES. ONE TO TWO
FEET PLUS OF SNOWFALL IS THUS EXPECTED ACROSS THE SAWTOOTH RANGE
OF CENTRAL ID AND THE HIGHER TERRAIN OF NORTHWEST WY. THE GREATEST
AMOUNTS ARE LIKELY DURING THE DAY 2 PERIOD (OZ TUE-0Z WED)...WHICH
IS WHEN PWAT AND MOISTURE FLUX ANOMALIES ARE GREATEST INTO THE
FAVORED TERRAIN.

...NORTHERN U.S...

TROUGHING MOVING ACROSS THE PLAINS ON MONDAY WILL CONTINUE TO
SHEAR AS IT MOVES EAST...WITH SOME OF THE ENERGY LIFTING TO THE
NORTH INTO CANADA...AND THE ENERGY AT THE BASE OF THE TROUGH
CLOSING OFF AND SINKING INTO THE GULF OF MEXICO. A WEAK COLD FRONT
WILL ACCOMPANY THIS TROUGH...AND COULD RESULT IN SOME LIGHT ICING
ACROSS PORTIONS OF CENTRAL/NORTHERN NEW ENGLAND ON TUESDAY NIGHT.
ALTHOUGH NOTHING SIGNIFICANT IS EXPECTED.

AN AREA OF LOW PRESSURE IS FORECAST TO EJECT EAST OUT OF MT INTO
THE NORTHERN PLAINS TUESDAY INTO WEDNESDAY. STILL QUITE A BIT OF
SPREAD WITH THIS FEATURE...BUT DEPENDING ON THE EXACT TRACK AND
STRENGTH OF THE LOW...SOME LIGHT SNOW ACCUMULATIONS ARE POSSIBLE
ACROSS NORTHERN MT/ND/MN.

THE PROBABILITY OF 0.25 INCHES OF ICE IS LESS THAN 10 PERCENT DAYS
1-3.

CHENARD



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