647  
FXUS01 KWBC 210800  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
359 AM EDT SAT JUL 21 2018  
 
VALID 12Z SAT JUL 21 2018 - 12Z MON JUL 23 2018  
 
...SLIGHT RISK OF SEVERE WEATHER AND FLASH FLOODING POSSIBLE IN  
THE EASTERN U.S....  
 
...SEVERE WEATHER POSSIBLE FROM THE NORTHERN HIGH PLAINS TO  
PORTIONS OF THE UPPER MIDWEST...  
 
...ABOVE NORMAL TEMPERATURES TO CONTINUE ACROSS THE SOUTHERN  
PLAINS ALONG WITH THE PACIFIC NORTHWEST...  
 
THE FRONTAL SYSTEM THAT HAS BEEN IMPACTING THE MISSISSIPPI,  
TENNESSEE AND OHIO VALLEYS WILL PUSH WESTWARD ACROSS THE OHIO AND  
TENNESSEE VALLEYS ALONG THE APPALACHIANS. SHOWERS AND  
THUNDERSTORMS WILL BE POSSIBLE ALONG THIS FRONT AS COPIOUS AMOUNTS  
OF MOISTURE AND INSTABILITY ARE IN PLACE FOR SUCH ACTIVITY. THE  
STORM PREDICTION CENTER HAS INDICATED THAT SEVERE WEATHER WILL BE  
A CONCERN ESPECIALLY IN THE SOUTHEAST AND THE SOUTHERN  
APPALACHIANS. MEANWHILE, A SURFACE LOW THAT HAS FORMED OFF THE  
COAST OF THE CAROLINAS WILL ALSO BE PUSHING NORTHWARD ALONG THE  
MID-ATLANTIC AND INTO THE NORTHEAST. THIS SYSTEM WILL ALSO BE A  
FOCAL POINT FOR HEAVY RAINFALL PARTICULARLY IN THE MID-ATLANTIC  
TODAY. THUS, FLASH FLOODING WILL BE A THREAT FOR THE MID-ATLANTIC  
AND PARTS OF THE OHIO VALLEY ON SATURDAY. BY SUNDAY, THE HEAVY  
RAIN IN THE LOW PRESSURE ALONG THE EAST COAST WILL SHIFT TOWARD  
THE NEW ENGLAND COAST WHERE FLASH FLOODING WILL ONCE AGAIN BE A  
CONCERN. SHOWERS AND THUNDERSTORMS CAN ALSO BE EXPECTED FOR THE  
OHIO VALLEY, MID-ATLANTIC, AND SOUTHEAST.  
 
A FRONTAL SYSTEM WILL SLIDE ACROSS THE NORTHERN HIGH PLAINS TODAY  
WHERE A LINE OF THUNDERSTORMS CAN BE EXPECTED. A SLIGHT RISK OF  
SEVERE WEATHER IS POSSIBLE ESPECIALLY IN EASTERN MONTANA/WYOMING  
AND WESTERN PORTIONS OF THE DAKOTAS. AS THIS SYSTEM MOVES INTO THE  
NORTHERN PLAINS, HIGHER AMOUNTS OF MOISTURE AVAILABLE WILL LEAD TO  
HEAVIER RAINFALL IN THE DAKOTAS. THIS LINE OF STORMS MAY ALSO  
PRODUCE SEVERE WEATHER--WHERE A SLIGHT RISK HAS BEEN HIGHLIGHTED  
IN THE NORTHERN PLAINS AND A SMALL PORTION OF THE UPPER MIDWEST. A  
MARGINAL RISK OF FLOODING WILL BE POSSIBLE FOR COLORADO WHERE SOME  
THUNDERSTORMS COULD PRODUCE FLASH FLOODING IN FAVORABLE TERRAIN.  
 
DANGEROUS HEAT REMAINS IN PLACE ACROSS THE SOUTHERN PLAINS,  
SOUTHWEST AND PACIFIC NORTHWEST AND WILL PERSIST THROUGH THE  
WEEKEND AND INTO MONDAY. EXCESSIVE HEAT WARNINGS AND HEAT  
ADVISORIES ARE IN PLACE ACROSS THESE REGIONS. HIGH TEMPERATURES  
WILL REACH WELL OVER THE CENTURY MARK ACROSS TEXAS AND OKLAHOMA  
THROUGH THIS WEEKEND--WITH AREAS NEAR THE DALLAS/FORT WORTH REGION  
REACHING TO 110! PORTIONS OF THE RED RIVER VALLEY COULD HAVE HEAT  
INDEX VALUES ABOVE 110 DEGREES. PORTIONS OF THE PACIFIC NORTHWEST  
WILL ALSO CONTINUE TO EXPERIENCE ABOVE NORMAL  
TEMPERATURES--ESPECIALLY BY THE END OF THE WEEKEND WHERE  
TEMPERATURES COULD REACH THE MID TO UPPER 90S AND EVEN REACH OVER  
100 IN SOME AREAS.  
 
REINHART  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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