334  
FXUS01 KWBC 251956  
PMDSPD  
 
SHORT RANGE FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
355 PM EDT TUE SEP 25 2018  
 
VALID 00Z WED SEP 26 2018 - 00Z FRI SEP 28 2018  
 
...WIDESPREAD RAIN AND THUNDERSTORMS ARE FORECAST IN THE EASTERN  
THIRD OF THE U.S., AHEAD OF A STRONG COLD FRONT...  
 
AN UPPER-LEVEL TROUGH CENTERED OVER THE CENTRAL U.S. WILL MAKE ITS  
WAY SLOWLY EASTWARD OVER THE NEXT COUPLE OF DAYS. AS IT DOES SO,  
IT WILL PUSH A STRONG COLD FRONT CURRENTLY LOCATED IN THE UPPER  
MIDWEST THROUGH THE MIDDLE MISSISSIPPI VALLEY AND INTO THE  
SOUTHERN PLAINS SOUTH AND EASTWARD. MOISTURE WILL STREAM AHEAD OF  
THE FRONT, LEADING TO WIDESPREAD RAIN AND THUNDERSTORMS FROM THE  
SOUTHERN ROCKIES TO THE NORTHEAST U.S. SOME AREAS COULD SEE FLASH  
FLOODING AND SEVERE WEATHER FROM THESE STORMS. MORE SPECIFICALLY,  
THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL/FLASH FLOODING  
THROUGH TUESDAY NIGHT FOR PARTS OF THE TENNESSEE AND OHIO VALLEYS,  
AS WELL AS FOR PORTIONS OF THE NORTHEAST. WEDNESDAY AND WEDNESDAY  
NIGHT'S HIGHEST THREAT FOR FLASH FLOODING WILL BE IN THE TENNESSEE  
VALLEY AND SOUTHERN APPALACHIANS. SLIGHT RISKS OF SEVERE WEATHER  
COVER PARTS OF THE UPPER MIDWEST, UPPER GREAT LAKES, AND OHIO  
VALLEY REGIONS THROUGH TUESDAY NIGHT. THE RISK SHIFTS EAST WITH  
THE FRONT ON WEDNESDAY, WITH A SLIGHT RISK OF SEVERE WEATHER IN  
PLACE IN THE MID-ATLANTIC REGION AND NORTHEAST.  
 
TEMPERATURE-WISE, THE COLD FRONT WILL SEPARATE COOLER THAN AVERAGE  
TEMPERATURES NORTH AND WEST OF THE FRONT FROM WARMER THAN AVERAGE  
TEMPERATURES TO THE SOUTH AND EAST. AS MENTIONED, AHEAD OF THE  
FRONT, WARM AND MOIST AIR WILL STREAM INTO THE SOUTHEAST, OHIO  
VALLEY, AND EASTERN SEABOARD. MANY RECORD WARM MINIMUM  
TEMPERATURES COULD BE SET ON WEDNESDAY MORNING. HIGH TEMPERATURES  
ALONG THE EASTERN SEABOARD WILL BE AROUND 10 DEGREES ABOVE NORMAL  
ON WEDNESDAY BEFORE THE FRONT PASSES. BEHIND THE FRONT, HIGH  
TEMPERATURES WILL BE WIDESPREAD IN THE 60S TO LOWER 70S.  
TEMPERATURES IN THE SOUTHERN HIGH PLAINS MAY NOT GET HIGHER THAN  
THE 50S ON WEDNESDAY, HOWEVER, WHICH IS 20 TO 30 DEGREES ABOVE  
NORMAL! THE WESTERN U.S. WILL BE WARMER THAN AVERAGE, UNDER THE  
INFLUENCE OF AN UPPER-LEVEL RIDGE. HIGH TEMPERATURES OF 10 TO 15  
DEGREES ABOVE NORMAL WILL BE WIDESPREAD THERE. WARM TEMPERATURES  
PLUS LOW HUMIDITY WILL LEAD TO ELEVATED FIRE DANGER IN NORTHERN  
CALIFORNIA IN PARTICULAR.  
 
ANOTHER FRONTAL SYSTEM IS FORECAST TO DROP SOUTHEASTWARD INTO THE  
NORTH CENTRAL U.S. ON WEDNESDAY AND THURSDAY. THIS WILL HELP CAUSE  
RAIN SHOWERS IN THE NORTHERN PLAINS AND INTO THE UPPER MIDWEST.  
SNOW SHOWERS ARE EXPECTED TO MIX IN ON THURSDAY IN THE NORTHERN  
HIGH PLAINS BEHIND THE COLD FRONT. THAT SECOND SHOT OF COOL AIR  
WILL LEAD TO HIGH TEMPERATURES IN THE 40S AND 50S THERE ON  
THURSDAY.  
 
TATE  
 
GRAPHICS AVAILABLE AT  
WWW.WPC.NCEP.NOAA.GOV/BASICWX/BASICWX_NDFD.PHP  

 
 
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