Prognostic Meteorological Discussion
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FXUS01 KWBC 210803
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
303 AM EST FRI NOV 21 2014

VALID 12Z FRI NOV 21 2014 - 12Z SUN NOV 23 2014

***UNSETTLED WEATHER PATTERN FOR THE WESTERN U.S.***

***INCREASING MOISTURE FOR THE CENTRAL U.S.***

***MODERATING TEMPERATURES FOR THE EASTERN U.S. THIS WEEKEND***

A PACIFIC STORM SYSTEM APPROACHING THE COAST ON FRIDAY IS EXPECTED
TO BRING WIDESPREAD PRECIPITATION FROM THE PACIFIC NORTHWEST TO
THE CENTRAL ROCKIES, AND THIS SHOULD LAST INTO THE WEEKEND AS THE
MOISTURE PLUME WORKS ITS WAY INLAND.  A SWATH OF STEADY RAIN AND
HIGH MOUNTAIN SNOW IS FORECAST ALONG AND JUST AHEAD OF THE FRONT,
AND SCATTERED RAIN/SNOW SHOWERS FOR MUCH OF THE GREAT BASIN AND
EVENTUALLY THE ROCKIES.  ELEVATION WILL BE A BIG FACTOR IN
DETERMINING PRECIPITATION TYPE.

FOR THE CENTRAL U.S., RETURN FLOW AROUND THE DEPARTING SURFACE
HIGH OVER THE EAST COAST WILL ALLOW FOR STEADILY INCREASING
MOISTURE FROM THE WESTERN GULF COAST TO THE OHIO VALLEY.  THE
NORTHERN EXTENT OF THIS MOISTURE MAY MANIFEST ITSELF AS FREEZING
DRIZZLE OR LIGHT FREEZING RAIN FROM NORTHERN MISSOURI TO THE
SOUTHERN GREAT LAKES REGION BEFORE WARMER AIR ARRIVES.  FARTHER
SOUTH, SHOWERS AND SOME THUNDERSTORMS WILL LIKELY INCREASE IN
COVERAGE THROUGH THE WEEKEND AS MOISTURE FROM THE GULF OF MEXICO
INTERACTS WITH A DEVELOPING SURFACE LOW OVER THE CENTRAL PLAINS BY
LATE SATURDAY.

AFTER A COLD DAY ON FRIDAY, TEMPERATURES FOR THE EASTERN U.S. WILL
FINALLY START A WARMING TREND BEGINNING ON SATURDAY AND LASTING
THROUGH MONDAY.  THE WARMER SOUTHERLY FLOW WILL ALLOW FOR READINGS
TO REACH THE 40S AND LOW 50S FOR MANY AREAS BY SATURDAY, AND ABOUT
5 TO 10 DEGREES WARMER ON SUNDAY.  SOME ISOLATED TO SCATTERED
SHOWERS AND STORMS ARE ALSO EXPECTED FOR SOUTH FLORIDA THROUGH THE
WEEKEND.

D. HAMRICK


GRAPHICS AVAILABLE AT WWW.WPC.NCEP.NOAA.GOV
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