167  
FXUS64 KMRX 211805  
AFDMRX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MORRISTOWN TN  
205 PM EDT MON SEP 21 2026  
   
..NEW DISCUSSION, AVIATION
 
 
   
KEY MESSAGES
 
 
UPDATED AT 204 PM EDT MON SEP 21 2026  
 
- WELL ABOVE NORMAL TEMPERATURES TO PERSIST THROUGH TUESDAY. BUT RELIEF  
IS ON THE WAY, WITH A PATTERN CHANGE EXPECTED MID-WEEK AND MUCH  
COOLER TEMPERATURES TO FOLLOW.  
 
- SCATTERED TO NUMEROUS SHOWERS ARE EXPECTED MONDAY THROUGH  
WEDNESDAY.  
 
- A FEW STRONG TO SEVERE STORM WITH DAMAGING WINDS COULD OCCUR  
MONDAY, WITH DAMAGING WINDS BEING THE PRIMARY THREAT. LOCALIZED  
FLOODING WILL BE POSSIBLE EACH DAY THROUGH WEDNESDAY AS WELL.  
 

 
   
DISCUSSION
 
 
ISSUED AT 204 PM EDT MON SEP 21 2026  
 
CURRENTLY A FEW THUNDERSTORMS OUT THERE, BUT ALSO SOME SCATTERED  
CLOUDS IN THE SOUTHERN VALLEY FROM MORNING/EARLY AFTERNOON  
CONVECTION. LOW CONFIDENCE ON LOCATION AND COVERAGE OF EXPECTED  
STORMS THIS AFTERNOON AS CAMS HAVE BEEN EXCEPTIONALLY POOR WITH  
MORNING CONVECTION AND AFTERNOON INITIALIZATION. IF/WHEN STORMS DO  
FORM THEN THE ATMOSPHERE SHOULD SUPPORT FAIRLY ROBUST  
THUNDERSTORM GROWTH, WITH THE STRONGEST STORMS CAPABLE OF  
PRODUCING DAMAGING WINDS/MICROBURSTS, SMALL HAIL, AND ISOLATED  
FLOODING AS THEY'LL BE MOVING VERY SLOW. A SIMILAR SET UP IS IN  
PLACE FOR TOMORROW AS WELL.  
 
ON WEDNESDAY THE PATTERN CHANGE GETS UNDERWAY AND WE BEGIN TO SEE A  
BREAK IN THE RELENTLESS HEAT. BY WEDNESDAY A REX BLOCK PATTERN TAKES  
SHAPE AS AN UPPER RIDGE BUILDS OVER THE CANADIAN SIDE OF THE GREAT  
LAKES REGION, AND THE AFOREMENTIONED OHIO VALLEY UPPER LOW DEEPENS  
OVER THE OHIO VALLEY AND CENTRAL APPALACHIAN REGION. WITH THE UPPER  
LOW TO OUR NORTH AND NW FLOW ALOFT, THIS WILL PUSH THE COLD FRONT  
THROUGH THE SOUTHERN APPALACHIANS AND ALLOW THE COOLDOWN TO BEGIN.  
BY THURSDAY THROUGH THE WEEKEND WE SHOULD SEE HIGHS TOPPING OUT ONLY  
IN THE 70'S FOR EVERY EXCEPT SOUTHEAST TN WHERE THEY MAY SQUEAK  
ACROSS THE 80 DEGREE MARK. THIS PATTERN WILL ALSO BE FAIRLY DRY WITH  
A MORE CANADIAN AIRMASS MOVING IN.  
 

 
   
AVIATION
 
 
(18Z TAFS)  
ISSUED AT 204 PM EDT MON SEP 21 2026  
 
ANOTHER AFTERNOON OF AFTERNOON SHOWERS AND THUNDERSTORMS EXPECTED  
WITH LIMITED COVERAGE. OVERNIGHT FOG ALSO EXPECTED AGAIN AT TRI,  
BUT FOG DENSITY WILL DEPEND ON HOW MUCH RAIN OCCURS.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
CHATTANOOGA AIRPORT, TN 71 92 69 85 / 40 70 40 70  
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 89 67 81 / 40 80 70 90  
OAK RIDGE, TN 68 87 66 80 / 40 70 60 80  
TRI CITIES AIRPORT, TN 65 83 63 76 / 60 80 70 90  
 

 
   
MRX WATCHES/WARNINGS/ADVISORIES
 
 
NC...NONE.  
TN...NONE.  
VA...NONE.  

 
 

 
 
DISCUSSION...99  
AVIATION...99  
 
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