Quantitative Precipitation Forecast
Issued by NWS

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14
000
FOUS11 KWBC 172057
QPFHSD

PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
357 PM EST FRI FEB 17 2017

VALID 00Z SAT FEB 18 2017 - 00Z TUE FEB 21 2017

DAYS 1 TO 3...

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

AN ACTIVE PATTERN WILL CONTINUE ACROSS THE WESTERN U.S. THIS
WEEKEND AND INTO EARLY NEXT WEEK...WITH WIDESPREAD SNOW EXPECTED
OVER THE HIGHER ELEVATIONS OF THE PACIFIC
NORTHWEST...CALIFORNIA...CENTRAL GREAT BASIN...AND ROCKIES.

AN ELONGATED UPPER TROUGH AND ASSOCIATED COLD FRONT EDGING INLAND
OVER CALIFORNIA AND THE SOUTHWEST FRIDAY NIGHT INTO SATURDAY WILL
BE THE INITIAL FOCUS OF THE FORECAST.  THE COMBINATION OF LOWERING
HEIGHTS AND DEEP SOUTHERLY FLOW TRANSPORTING ANOMALOUS MOISTURE
NORTHWARD AHEAD OF THESE FEATURES WILL BRING WIDESPREAD
PRECIPITATION ACROSS THE WESTERN U.S....WITH OROGRAPHIC EFFECTS
ENHANCING SNOWFALL TOTALS ALONG THE WINDWARD TERRAIN OF THE SIERRA
NEVADA RANGE...CENTRAL GREAT BASIN...AND EVEN WITHIN THE HIGHER
ELEVATIONS OF THE SAN BERNARDINO AND SAN GABRIEL MOUNTAINS OF
SOUTHERN CALIFORNIA.  AS THE ELONGATED UPPER TROUGH AND COLD FRONT
CONTINUE TO PRESS INLAND SATURDAY INTO EARLY SUNDAY...THE BEST
LIFT AND MOISTURE TRANSPORT...AND GREATEST CHANCE FOR SNOW...WILL
SHIFT EASTWARD OVER THE SOUTH FACING SLOPES OF THE WASATCH AND
UINTA MOUNTAINS OF UTAH...SAN JUANS OF SOUTHWEST COLORADO...AND
MOGOLLON RIM IN ARIZONA.  MEANWHILE...PERIODS OF HEAVY SNOW WILL
ALSO BE POSSIBLE FARTHER NORTH OVER THE CASCADES...NORTHERN
ROCKIES...AND HIGHER ELEVATIONS OF THE SHASTA RANGE IN NORTHERN
CALIFORNIA AS NORTHERN STREAM SHORTWAVE ENERGY LIFTS THROUGH THE
PACIFIC NORTHWEST ON SATURDAY AND AN UPSTREAM WEAKENING PACIFIC
COLD FRONT MOVES INLAND ON SUNDAY.

TOWARDS THE END OF THE FORECAST PERIOD...ATTENTION WILL SHIFT
TOWARDS THE NEXT UPPER TROUGH AND SURGE OF ANOMALOUS MOISTURE
APPROACHING THE WESTERN U.S. SUNDAY NIGHT INTO MONDAY.  DESPITE
SOME UNCERTAINTY WITH THE EXACT AMPLITUDE OF THE TROUGH AND
DETAILS OF THE ASSOCIATED SURFACE LOW/LOWS...THERE IS A STRONG
SIGNAL FOR SIGNIFICANT SNOWFALL TOTALS OVER THE SHASTAS AND
ESPECIALLY ALONG THE SIERRA RANGE.

FOR DETAILS ON THE HEAVY RAINFALL THREAT IN CALIFORNIA AND THE
SOUTHWEST PLEASE REFER TO THE QPFPFD...AND PLEASE REFER TO PMDHMD
FOR INFORMATION ON MODEL SPREAD AND PREFERENCES.


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


GERHARDT

$$





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.