130  
FXUS01 KWBC 202000  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
359 PM EDT FRI JUL 20 2018  
 
VALID 00Z SAT JUL 21 2018 - 00Z MON JUL 23 2018  
 
...A MODERATE RISK OF SEVERE THUNDERSTORMS IS POSSIBLE ACROSS THE  
TENNESSEE AND OHIO VALLEYS....  
 
...HEAVY RAIN EXPECTED TO IMPACT THE OHIO VALLEY AND ALONG THE  
EAST COAST...  
 
...ABOVE NORMAL TEMPERATURES TO CONTINUE ACROSS THE SOUTHERN  
PLAINS ALONG WITH THE PACIFIC NORTHWEST...  
 
A DEEP LOW PRESSURE SYSTEM IS CURRENTLY IMPACTING THE UPPER GREAT  
LAKES REGION, WITH A STRONG COLD FRONG STRETCHING SOUTHWARD  
THROUGH THE OHIO AND MIDDLE MISSISSIPPI VALLEY, THEN EASTWARD TO  
THE CENTRAL PLAINS. COPIOUS AMOUNTS OF MOISTURE WILL POOL ALONG  
THE FRONT ALONG WITH UNSTABLE AIR, GENERATING STRONG THUNDERSTORMS  
WITH HEAVY RAINFALL THROUGH THIS REGION THIS AFTERNOON AND  
EVENING. THE BEST CONVECTION IS CURRENTLY LOCATED ACROSS THE OHIO  
VALLEY AND PORTIONS OF THE TENNESSEE VALLEY. THE STORM PREDICTION  
CENTER HAS OUTLINED MUCH OF SOUTHERN INDIANA, CENTRAL AND WESTERN  
KENTUCKY, AND NORTHWEST TENNESSEE AS BEING IN A MODERATE RISK FOR  
SEVERE WEATHER, WHILE MUCH OF THE REST OF THE REGION IS IN A  
SLIGHT OR MODERATE RISK. A SLIGHT RISK OF EXCESSIVE RAINFALL IS  
ALSO IN PLACE ACROSS THIS REGION. THE STRONG SHOWERS AND  
THUNDERSTORMS ARE EXPECTED TO CONTINUE THROUGHOUT THE EVENING AND  
INTO THE OVERNIGHT.  
 
BY SATURDAY, THE SYSTEM PUSHES EASTWARD, AND THE COLD FRONT  
QUICKLY DIVES SOUTHWARD. THE STORM PREDICTION CENTER HAS OUTLINED  
MUCH FO THE SOUTHEAST AND EASTERN TENNESEE VALLEY AS HAVING A  
SLIGHT RISK OF SEEING SEVERE STORMS THROUGH THE DAY SATURDAY.  
PRECIPITATION WILL ALSO INCREASE ACROSS THE LOWER GREAT LAKES  
SOUTHWARD INTO GEORGIA AND SOUTH CAROLINA, WHERE THE WEATHER  
PREDICTION CENTER HAS OUTLINED A MARGINAL RISK FOR EXCESSIVE  
RAINFALL.  
 
A DEVELOPING LOW OFF THE CAROLINA COAST WILL SLOWLY MOVE NORTHWARD  
ALONG THE MID-ATLANTIC AND INTO THE NORTHEAST THROUGH THE WEEKEND.  
CURRENTLY, HEAVY RAINFALL ASSOCIATED WITH THIS SYSTEM IS  
CONCENTRATED ACROSS THE COASTAL PORTIONS OF NORTH AND SOUTH  
CAROLINA WHERE A SLIGHT RISK OF FLASH FLOODING WILL BE A CONCERN  
THROUGH TONIGHT. AS THE LOW MOVES TOWARD THE NEW ENGLAND  
COASTLINE BY LATE SATURDAY NIGHT/EARLY SUNDAY MORNING, SO TOO WILL  
THE HEAVY RAINFALL AND SLIGHT CHANCE OF EXCESSIVE RAIN/FLASH  
FLOODING.  
 
DANGEROUS HEAT REMAINS IN PLACE ACROSS MUCH OF THE SOUTH-CENTRAL  
AND SOUTHWEST UNITED STATES AND IS EXPECTED TO PERSIST THROUGH THE  
WEEKEND. EXCESSIVE HEAT WARNINGS AND HEAT ADVISORIES ARE IN PLACE.  
HIGH TEMPERATURES WILL REACH WELL OVER THE CENTURY MARK ACROSS  
TEXAS AND OKLAHOMA THROUGH THIS WEEKEND. 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. ELSEWHERE,  
MONSOONAL MOISTURE WILL FIRE OFF THUNDERSTORMS ACROSS THE DESERT  
SOUTHWEST--WHERE FLASH FLOODING COULD OCCUR IN FAVORED TERRAIN,  
DESERT REGIONS, AND URBAN CORRIDORS. A MARGINAL RISK OF FLASH  
FLOODING IS POSSIBLE THROUGH SUNDAY.  
 
WIX  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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