461  
FXUS01 KWBC 210637  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
236 AM EDT MON SEP 21 2026  
 
VALID 12Z MON SEP 21 2026 - 12Z WED SEP 23 2026  
 
...EXCESSIVE RAINFALL RISK FOR PORTIONS OF THE APPALACHIANS AND  
MID-ATLANTIC ON MONDAY...  
 
...SEVERE THUNDERSTORM RISK FOR PORTIONS OF THE SOUTHEAST INTO  
CENTRAL APPALACHIANS ON MONDAY...  
 
...EXCESSIVE RAINFALL RISK FOR PORTIONS OF NEW MEXICO AND SOUTHERN  
PLAINS THROUGH TUESDAY...  
 
AN UPPER TROUGH AND SURFACE FRONTAL SYSTEM WILL PROGRESS ACROSS  
CENTRAL U.S. TOWARDS THE OHIO VALLEY/MID-ATLANTIC AND WILL  
GRADUALLY DRAPE ACROSS PORTIONS OF THE SOUTHERN PLAINS INTO THE  
SOUTHEAST. THIS WILL BRING PERIODS OF SHOWERS AND THUNDERSTORMS  
ALONG THE BOUNDARY. MULTIPLE ROUNDS OF MODERATE TO LOCALLY HEAVY  
RAIN ARE EXPECTED TO DEVELOP OVER PORTIONS OF THE APPALACHIANS AND  
MID-ATLANTIC ON MONDAY, AS ELEVATED INSTABILITY AND MOISTURE  
INTERACTS WITH THE BOUNDARY AND SURFACE TROUGH. THIS WILL LEAD TO  
EXCESSIVE RAINFALL/FLASH FLOODING CONCERNS OVER PORTIONS OF THE  
APPALACHIANS AND SEVERE THUNDERSTORMS CONCERNS OVER PORTIONS OF  
THE APPALACHIANS INTO THE SOUTHEAST. ON TUESDAY, ADDITIONAL  
SHORTWAVE ENERGY OVER THE OHIO VALLEY/MID-ATLANTIC WILL BRING  
ADDITIONAL SHOWERS AND THUNDERSTORMS. LOCALLY ELEVATED INSTABILITY  
AND ORGANIZED CONVECTION MAY PRODUCE HIGH RAINFALL RATES, LEADING  
TO ANOTHER DAY OF EXCESSIVE RAINFALL OVER PORTIONS OF THE OHIO  
VALLEY AND MID-ATLANTIC, WHILE SEVERE THUNDERSTORMS CONTINUE FOR  
PORTIONS OF THE APPALACHIANS AND SOUTHEAST.  
 
FURTHERMORE, A MOIST TROPICAL AIRMASS WILL CONTINUE OVER PORTIONS  
OF FLORIDA, BRINGING DAILY SHOWERS AND THUNDERSTORMS, ESPECIALLY  
OVER SOUTHERN FLORIDA. LOCALLY HEAVY DOWNPOURS WILL BRING FLOODING  
CONCERNS THROUGH TUESDAY. ACROSS THE SOUTHWEST, GULF AND PACIFIC  
MOISTURE WILL FUNNEL INTO PORTIONS OF THE SOUTHERN PLAINS,  
SOUTHWEST, AND FOUR CORNERS BRINGING A INCREASE IN SHOWERS AND  
THUNDERSTORMS ON MONDAY, WITH ACTIVITY BECOMING MORE WIDESPREAD ON  
TUESDAY. THE COMBINATION OF DEEP MOISTURE AND INSTABILITY MAY LEAD  
TO LOCALLY HEAVY RAINFALL AND FLASH FLOODING ACROSS NEW MEXICO AND  
PORTIONS OF WESTERN TEXAS THROUGH TUESDAY.  
 
A GRADUAL TRANSITION TO COOLER TEMPERATURES IS EXPECTED ACROSS THE  
NORTH-CENTRAL AND EASTERN U.S. BEHIND THE ADVANCING FRONTAL SYSTEM  
WITH HIGHS IN THE 60S. THE SOUTHEAST AND SOUTHERN PLAINS WILL  
REMAIN WARMER AND HUMID WITH HIGHS IN THE 80S AND 90S.  
 
OUDIT  
 
GRAPHICS AVAILABLE AT  
HTTPS://WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  
 
 
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