469  
FXUS64 KMRX 222313  
AFDMRX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE MORRISTOWN TN  
713 PM EDT TUE JUL 22 2025  
   
..NEW AVIATION
 
 
   
SHORT TERM AND LONG TERM
 
 
(THIS EVENING THROUGH NEXT TUESDAY)  
ISSUED AT 130 PM EDT TUE JUL 22 2025  
 
KEY MESSAGES:  
 
1. A DRIER SURFACE AIR MASS AND RIDGING ALOFT WILL BRING LOWER  
CHANCES OF SHOWERS AND STORMS THROUGH FRIDAY, WITH THE RAIN CHANCES  
MAINLY IN THE MOUNTAINS.  
 
2. RAIN CHANCES RISE OVER THE WEEKEND AS THE UPPER RIDGE WEAKENS AND  
LOW LEVEL MOISTURE INCREASES.  
 
DISCUSSION:  
 
A BACKDOOR FRONT IS NEAR OUR NORTHERN BORDER THIS AFTERNOON,  
EVIDENCED BY A WIND SHIFT TO N-NE, A DROP IN DEWPOINTS TO MID/UPPER  
60S IN VA/WV/KY, AND A GRADIENT IN CUMULUS DEVELOPMENT. SOME  
SCATTERED SHOWERS HAVE DEVELOPED JUST SOUTH OF THE FRONT IN SW VA  
AND NE TN, BUT CONVECTION IS HAVING A HARD TIME DEVELOPING  
VERTICALLY WHERE DRY AIR ALOFT IS PRESENT. AS THE FRONT PUSHES  
SOUTHWARD THROUGH THE EVENING, A FEW SHOWERS MAY POP UP IN THE  
CENTRAL AND SOUTHERN TN VALLEY, BUT COVERAGE SHOULD REMAIN ISOLATED  
TO SCATTERED. THE FRONT APPEARS TO BE NEAR OUR SOUTHERN BORDER  
OVERNIGHT, BASED ON MODEL STABILITY GRADIENTS, AND THE CAMS SHOW  
SOME SHOWERS PERSISTING IN SW NC NEAR THE FRONT. TOMORROW LOOKS  
QUITE STABLE IN MODEL SOUNDINGS, ESPECIALLY IN NORTHERN SECTIONS  
WHERE SURFACE DEWPOINTS WILL BE IN THE 60S, PLUS THE FLOW FROM THE  
SURFACE TO AROUND 700 MB TURNS EASTERLY AND DOWNSLOPE OFF THE  
MOUNTAINS. SO CONVECTION WILL BE LIMITED TO SOUTHERN SECTIONS AND  
THE HIGHER TERRAIN, AND COVERAGE SHOULD ONLY BE ISOLATED TO  
SCATTERED. THE NBM POPS WERE TRIMMED BACK SLIGHTLY.  
 
THE SURFACE HIGH OFF THE NEW ENGLAND COAST WILL EXTEND SW INTO THE  
SOUTHERN APPALACHIANS THROUGH THURSDAY, WHILE A MID/UPPER LEVEL  
RIDGE WILL BE CENTERED OVER THE MID MS AND TN VALLEYS. THE NET  
EFFECT OF THIS PATTERN WILL BE TO SUPPRESS CONVECTION AND DRY THE  
SURFACE AIR MASS. SURFACE DEWPOINTS WILL BE QUITE TOLERABLE FOR THIS  
TIME OF YEAR (UPPER 60S TO LOWER 70S), WHICH WILL KEEP THE HEAT  
INDEX WELL UNDER ADVISORY CRITERIA DESPITE HIGHS IN THE 90S THROUGH  
FRIDAY. AGAIN, THE NBM POPS APPEAR TOO HIGH FOR THIS PATTERN, AND  
WILL BE CUT BACK. NBM 10TH PERCENTILE DEWPOINTS WILL ALSO BE USED.  
 
THE SURFACE HIGH OVER THE ATLANTIC SHIFTS SOUTHWARD THROUGH THE  
WEEKEND, PRODUCING A MORE SOUTHERLY LOW LEVEL FLOW FROM THE GULF.  
MEANWHILE, THE RIDGE ALOFT STARTS TO LOOSEN ITS GRIP ON THE REGION,  
SHIFTING WEST OF THE MS RIVER. THIS WILL INCREASE THE CHANCE OF RAIN  
OVER THE WEEKEND AND EARLY NEXT WEEK.  
   
AVIATION
 
 
(18Z TAFS)  
ISSUED AT 130 PM EDT TUE JUL 22 2025  
 
DRIER AIR WORKING INTO THE AREA FROM THE NORTH SHOULD LOWER  
DEWPOINTS ENOUGH TONIGHT TO KEEP THE CHANCE OF FOG LOW AT ALL TAF  
SITES. STILL, SOME GUIDANCE SHOWS FOG AT TRI, ADDING SOME  
UNCERTAINTY. WILL LEAVE FOG OUT FOR THIS SET AS THAT SEEMS LIKE THE  
MOST LIKELY OCCURRENCE. VFR CONDITIONS ARE FORECAST FOR ALL  
SITES, WITH LIGHT NE WINDS.  
 

 
   
LONG TERM
 
 

 
   
AVIATION
 
 
(00Z TAFS)  
ISSUED AT 711 PM EDT TUE JUL 22 2025  
 
VFR CONDITIONS EXPECTED TO PERSIST THROUGH THE PERIOD. A VERY LOW  
CHANCE FOG MAY FORM OVERNIGHT AT KTRI, BUT ADVANCING LOWER  
DEWPOINTS IS FORECAST TO HOLD FOG AT BAY. OTHERWISE LIGHT WINDS  
THROUGH THE PERIOD, WITH A LOW CHANCE OF SMALL SHOWERS SOUTH OF  
KNOXVILLE TOMORROW AFTERNOON, SIMILAR IN INTENSITY TO TODAY'S WEAK  
SHOWERS.  
 

 
   
PRELIMINARY POINT TEMPS/POPS
 
 
CHATTANOOGA AIRPORT, TN 73 92 72 93 / 20 30 0 30  
KNOXVILLE MCGHEE TYSON AIRPORT, TN 71 93 71 94 / 20 20 0 20  
OAK RIDGE, TN 71 92 72 93 / 20 10 0 20  
TRI CITIES AIRPORT, TN 67 89 65 91 / 20 10 0 10  
 

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

 
 

 
 
SHORT TERM...DGS  
LONG TERM....DGS  
AVIATION...WELLINGTON  
 
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