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975 
FXUS01 KWBC 210810
PMDSPD

SHORT RANGE FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
410 AM EDT TUE MAY 21 2013

VALID 12Z TUE MAY 21 2013 - 12Z THU MAY 23 2013

...WIDESPREAD SEVERE WEATHER AND HEAVY RAINFALL THREAT ARE
EXPECTED ALONG A SLOW-MOVING COLD FRONT MIGRATING THROUGH THE
NATION'S MID-SECTION...

...WINDY...COOL AND WET CONDITIONS ARE IN THE FORECAST FOR THE
PACIFIC NORTHWEST AND NORTHERN ROCKIES... AND

...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER FLORIDA
AND UP INTO THE MID-ATLANTIC REGION...

A COLD FRONT EDGING EASTWARD THROUGH THE NATION'S MID-SECTION WILL
CONTINUE TO BE A BIG WEATHER MAKER DURING THE SHORT RANGE PERIOD. 
ANOMALOUS AMOUNTS OF MOISTURE SURGING NORTHWARD OUT OF THE
GULF...COMBINED WITH STRONG DYNAMICS ALOFT...SHOULD PRODUCE
ORGANIZED CONVECTION ALONG AND AHEAD OF THE SLOW-MOVING FRONTAL
BOUNDARY. HEAVY RAINFALL MAY ACCOMPANY THE MORE INTENSE SHOWERS
AND THUNDERSTORMS WITH SEVERE WEATHER EXPECTED FROM THE SOUTHERN
PLAINS TO UPPER MIDWEST/UPPER GREAT LAKES. A MODERATE RISK OF
SEVERE STORMS WILL BE LOCATED TODAY AND TONIGHT FOR NORTHEAST
TEXAS INTO THE ARK-LA-TEX AND SOUTHERN OZARKS. PLEASE REFER TO THE
STORM PREDICTION CENTER FOR THE LATEST INFORMATION AND UPDATES FOR
SEVERE WEATHER. FARTHER NORTH...MOISTURE WRAPPING AROUND A
SLOW-MOVING UPPER-LEVEL LOW ANCHORED IN THE UPPER MISSISSIPPI
VALLEY AND A STATIONARY FRONT DRAPED TO THE EAST OF THIS LOW WILL
BE THE FOCUS FOR LIGHT TO MODERATE RAINFALL AND EMBEDDED
THUNDERSTORMS FROM THE NORTHERN PLAINS TO THE GREAT LAKES AND INTO
SOUTHERN NEW ENGLAND DURING THE NEXT FEW DAYS. 

A VIGOROUS UPPER VORTEX SETTLING IN OVER THE PACIFIC NORTHWEST
WILL SLOWLY PUSH A COLD FRONT INLAND THROUGH THE WEST AND NORTHERN
ROCKIES. MODERATE  MOISTURE...INSTABILITY AND COLD AIR ALOFT WILL
PRODUCE SCATTERED SHOWERS AND A FEW THUNDERSTORMS. WINDY
CONDITIONS ALONG THE FRONT SHOULD ENHANCE PRECIPITATION AMOUNTS
ALONG THE WINDWARD SLOPES OF THE HIGHER TERRAIN. WITH CONDITIONS
NOTICEABLY COOLER BEHIND THE FRONT...TEMPERATURES COULD BRIEFLY
FALL BELOW FREEZING AT ELEVATION WITH THE POSSIBILITY OF SNOW
SHOWERS IN THE WASHINGTON AND OREGON CASCADES.

ACROSS THE EAST AND SOUTHEAST...WEAK ENERGY ALOFT AND WARM
ADVECTION SHOULD KEEP CONDITIONS RIPE FOR SCATTERED SHOWERS AND
THUNDERSTORMS OVER FLORIDA AND NORTHWARD INTO THE MID-ATLANTIC
STATES.

GERHARDT/VOJTESAK

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