Prognostic Meteorological Discussion
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FXUS01 KWBC 220743
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
342 AM EDT TUE AUG 22 2017

VALID 12Z TUE AUG 22 2017 - 12Z THU AUG 24 2017

...COLD FRONT SWEEPING ACROSS THE EASTERN U.S. WILL BRING WITH IT
HEAVY RAINFALL AND SEVERE WEATHER...

...SHOWERS AND THUNDERSTORMS EXPECTED TO CONTINUE ACROSS THE
SOUTHERN ROCKIES...


A COLD FRONT STRETCHED FROM SOUTHEASTERN CANADA TO THE ROCKIES
WILL BE THE FOCUS FOR WEATHER ACROSS THE EASTERN U.S. DURING THE
SHORT TERM PERIOD.  ON TUESDAY, THIS FRONT WILL MOVE SOUTHEASTWARD
ACROSS THE GREAT LAKES, TENNESSEE VALLEY, MISSISSIPPI VALLEY AND
THE SOUTHERN PLAINS.  WITH COPIOUS AMOUNTS OF MOISTURE IN PLACE
ALONG WITH INSTABILITY, CONVECTION WILL CONTINUE DEVELOPING ALONG
AND AHEAD OF THE FRONT.  ON TUESDAY THE HEAVIEST RAINFALL WILL
MOVE FROM THE MIDDLE MISSISSIPPI VALLEY AND INTO THE SOUTHERN
PLAINS/LOWER MISSISSIPPI VALLEY. FARTHER NORTH, THE COLD FRONT
WILL ALSO BEGIN APPROACHING THE LOWER GREAT LAKES AND NEW
ENGLAND--BRINGING CHANCES OF FLASH FLOODING AND SEVERE WEATHER TO
THESE REGIONS. AS THE COLD FRONT SLOWS ALONG THE RED RIVER VALLEY
LATE TUESDAY NIGHT, HEAVY RAINFALL WILL ALSO DEVELOP IN THIS
REGION AND SLOWLY PUSH SOUTHWARD.  BY WEDNESDAY, THE COLD FRONT
WILL APPROACH THE EAST COAST WHILE SINKING SOUTHWARD ACROSS THE
SOUTHEAST.  ONCE AGAIN, PRECIPITATION WILL ALSO MOVE ALONG THE
FRONT. BY THURSDAY MORNING, SHOWERS AND THUNDERSTORMS WILL
CONCENTRATE IN THE COASTAL CAROLINAS AND NORTH/CENTRAL TEXAS.

THUNDERSTORMS ACROSS THE SOUTHERN ROCKIES WILL CONTINUE TO FIRE
OFF EACH AFTERNOON OVER THE SHORT TERM PERIOD.  EXPECT A MARGINAL
RISK FOR FLASH FLOODING AS SOME OF THESE STORMS COULD PRODUCE
HEAVY DOWNPOURS THAT MAY LEAD TO FLASH FLOODING.  A SLOW-MOVING
UPPER LEVEL LOW WILL LINGER ALONG THE CALIFORNIA COAST--WHICH WILL
GIVE WAY TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS AREAS IN
CALIFORNIA AND THE GREAT BASIN. THE HEAVIEST RAINFALL IS FORECAST
TO BE IN THE SIERRA NEVADA MOUNTAIN RANGE.  MEANWHILE, FARTHER
NORTH, A COLD FRONT WILL MOVE ACROSS THE PACIFIC NORTHWEST ON
WEDNESDAY NIGHT/THURSDAY MORNING, BRINGING LIGHT SHOWERS
ESPECIALLY IN THE NORTHERN ROCKIES.

TYPICAL SUMMERTIME THUNDERSTORMS WILL OCCUR ALONG THE GULF COAST
STATES EACH AFTERNOON.  THERE WILL BE AN INCREASE IN COVERAGE ON
WEDNESDAY AS THE COLD FRONT APPROACHES THE COASTLINE.  FLORIDA CAN
ALSO EXPECT AN INCREASE IN THUNDERSTORM ACTIVITY AS AN INVERTED
TROUGH APPROACHES ITS ATLANTIC COASTLINE THIS MORNING.  IN TERMS
OF TEMPERATURES, COOLER CONDITIONS WILL SETTLE IN BEHIND THE
STRONG COLD FRONT SWEEPING THE EASTERN U.S.  IN FACT, MOST OF THE
COUNTRY EAST OF THE ROCKIES WILL BE BELOW AVERAGE ON THURSDAY.
AHEAD OF THE INCOMING COLD FRONT, THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES WILL EXPERIENCE WARMER THAN NORMAL TEMPERATURES.
AS THE COLD FRONT PUSHES ACROSS THIS REGION, TEMPERATURES WILL
DROP BACK DOWN TO NEAR NORMAL OR SLIGHTLY BELOW NORMAL.


REINHART


GRAPHICS AVAILABLE AT
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP
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