199  
FXUS64 KMRX 171106  
AFDMRX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MORRISTOWN TN  
706 AM EDT THU SEP 17 2026  
   
..NEW AVIATION
 
 
   
KEY MESSAGES
 
 
UPDATED AT 658 AM EDT THU SEP 17 2026  
 
- WELL ABOVE NORMAL TEMPERATURES TO PERSIST THROUGH EARLY NEXT WEEK.  
SLIGHT COOLING TOWARDS THE END OF THE FORECAST PERIOD MID-WEEK.  
 
- INCREASING RAIN CHANCES FOR THE HIGHER TERRAIN THIS WEEKEND INTO  
NEXT WEEK WITH THE VALLEY LEAST LIKELY TO SEE RAIN, SIMILAR TO A  
TYPICAL SUMMER PATTERN.  
 

 
   
DISCUSSION
 
 
ISSUED AT 239 AM EDT THU SEP 17 2026  
 
AN APPROXIMATE 600 DAM UPPER HIGH CENTERED NEARLY OVERHEAD EARLIER,  
HAS BEGUN IT'S JOURNEY OF WEAKENING AND CYCLING BACK WEST TODAY.  
RECORD HEAT FOR MID SEPTEMBER WILL CONTINUE THOUGH. AT THE SURFACE,  
HIGH PRESSURE OVER THE E AND NE, WILL ALSO WEAKEN, LEAVING OUR AREA  
MORE SUSCEPTIBLE TO JUST ENOUGH INSTABILITY FOR DIURNAL SHOWER  
DEVELOPMENT. ISOLATED TO SCATTERED SHOWERS/STORM WILL BE POSSIBLE  
FOR THE SOUTHERN APPALACHIANS, NE TENNESSEE, AND SW VIRGINIA THIS  
AFTERNOON AND EVENING. TOMORROW MAY INTRODUCE SOME ISOLATED TO  
SCATTERED DEVELOPMENT FOR PARTS OF THE CENTRAL AND NORTHERN VALLEY.  
SUMMER-LIKE PRECIPITATION CHANCES FOR THE AFTERNOON AND EVENING WILL  
PERSIST INTO NEXT WEEK WITH POSSIBLE EXPANSION IN COVERAGE SOME DAYS.  
 
LOWER TO MID WITH SOME UPPER 90S, ARE FORECAST THROUGH THE WEEKEND,  
BEFORE A SLIGHT TURN DOWNWARD TOWARDS THE END OF THE FORECAST PERIOD  
OR AS WE APPROACH THE MIDDLE OF NEXT WEEK. UPPER 90S TO LOW 100S  
HEAT INDICES WILL BE POSSIBLE FROM THE SOUTHERN VALLEY UP THROUGH  
THE CENTRAL VALLEY. THE HIGHEST HEAT INDICES MAY PEAK TOMORROW.  
THOUGH MOST OF THE AREA WON'T REACH HEAT ADVISORY CRITERIA, THAT  
DOESN'T MEAN TO LET YOUR GUARD DOWN WHEN IT COMES TO BEING OUTDOORS,  
STAYING COOL, AND HYDRATED. OUR DAYTIME HIGHS YESTERDAY (BEFORE  
CLIMATE OFFICIALLY RUNS AFTER THIS DISCUSSION), TIED THE DAILY  
RECORD AT TRI-CITIES. THAT MAKES CHATTANOOGA'S STREAK OF 90 AND  
ABOVE AT 44 DAYS AND COUNTING, WITH NO BREAK IN SIGHT.  
 

 
   
AVIATION
 
 
(12Z TAFS)  
ISSUED AT 658 AM EDT THU SEP 17 2026  
 
FOG HAS DEVELOPED AT TRI WITH REDUCTIONS TO IFR AND LIFR BEING  
REPORTED. THIS SHOULD LIFT QUICKLY IN THE NEXT HOUR OR SO,  
IMPROVING TO VFR WITH LIGHT AND VARIABLE WINDS THROUGH THE DAY.  
THERE ARE SOME RAIN CHANCES THIS AFTERNOON AND EARLY EVENING,  
FOCUSED CLOSER TO TRI, BUT REDUCTIONS ARE NOT EXPECTED. FOG IS  
POSSIBLE AGAIN TONIGHT AT TRI.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
CHATTANOOGA AIRPORT, TN 97 73 98 72 / 0 10 10 10  
KNOXVILLE MCGHEE TYSON AIRPORT, TN 94 72 95 70 / 10 10 20 10  
OAK RIDGE, TN 94 71 95 70 / 10 10 30 10  
TRI CITIES AIRPORT, TN 90 68 89 67 / 30 20 50 10  
 

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

 
 

 
 
DISCUSSION...KS  
AVIATION...BW  
 
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