998
FXUS64 KMRX 221719
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
119 PM EDT WED JUL 22 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1252 PM EDT WED JUL 22 2026
- MULTIPLE ROUNDS OF SHOWERS AND STORMS WILL AFFECT THE AREA
TONIGHT INTO AT LEAST WEDNESDAY NIGHT AS A SLOW MOVING COLD
FRONT APPROACHES FROM THE NORTHWEST AND MOVES THROUGH THE
FORECAST AREA.
- VERY HEAVY RAINFALL WILL BE POSSIBLE WITH A THREAT OF FLASH
FLOODING THROUGH WEDNESDAY NIGHT, WITH THE PRIMARY THREAT
MAINLY NORTHERN HALF OR TWO THIRDS OF THE AREA TONIGHT INTO
WEDNESDAY BEFORE SHIFTING SOUTHWARD LATE WEDNESDAY.
- BELOW NORMAL HIGH TEMPERATURES CAN BE EXPECTED THURSDAY THROUGH
SATURDAY, THEN TEMPERATURES WILL NOT BE FAR FROM NORMAL FOR THE
REMAINDER OF THE PERIOD.
DISCUSSION
ISSUED AT 111 AM EDT WED JUL 22 2026
UPPER TROUGHING OVER THE EASTERN CONUS, AND EMBEDDED SHORTWAVES
MOVING THROUGH THE OHIO VALLEY, WILL HELP TO PUSH A COLD FRONT
THROUGH OUR AREA OVER THE NEXT 24 HOURS OR SO. IT'S CURRENTLY
SITUATED WELL TO OUR NORTHWEST, BUT IT WILL BE APPROACHING FROM THE
NORTHWEST AFTER DAYBREAK TOMORROW, FINALLY PUSHING IN THE SOUTHERN
PARTS OF THE CWA OR PERHAPS COMPLETELY SOUTH OF THE AREA BY LATE
WEDNESDAY NIGHT. THE MAIN CONCERN WITH THIS FRONT WILL BE THE
POTENTIAL FOR TRAINING STORMS THAT DEVELOP DURING THE PRE-DAWN HOURS
LATER TONIGHT AND THE ASSOCIATED FLOODING RISKS THAT OCCUR, AND THEN
WHETHER OR NOT ADDITIONAL CONVECTION FIRES ALONG THE FRONT BEFORE IT
MOVES OUT OF OUR AREA WEDNESDAY NIGHT FOR A FLOOD RISK IN OUR
SOUTHERN CWA.
FOR THE PRE-DAWN HOURS OVERNIGHT, SEVERAL RUNS OF CAM GUIDANCE THIS
AFTERNOON AND EVENING HAVE BEEN POINTING TOWARDS DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS ACROSS THE NORTHERN TN VALLEY AND INTO OUR
VA COUNTIES AS FORCING AHEAD OF THE COLD FRONT COINCIDE WITH
CONFLUENT AND FRONT-PARALLEL H85 FLOW MOVE INTO THAT REGION. THIS
WOULD SUPPORT TRAINING CONVECTION ALONG/AHEAD OF THE FRONT, YIELDING
THE POTENTIAL FOR HIGH RAINFALL AMOUNTS. HREF PROBABILITIES SHOW 30
TO 40 PERCENT ODDS FOR 6HR RAINFALL AMOUNTS TO EXCEED 2" WHILE
SEVERAL HRRR RUNS THIS EVENING HAVE SHOWN EXPLICIT DETERMINISTIC
RAINFALL AMOUNTS IN THE 3-5" RANGE SOMEWHERE OVER THE NORTHERN TN
VALLEY AND NORTHERN EAST TENNESSEE MOUNTAINS. ALL OF THIS YIELDS
CONFIDENCE THAT THERE IS STILL A RISK OF FLASH FLOODING TONIGHT.
BELIEVE THE FLASH FLOOD WATCH IN PLACE ADEQUATELY COVERS THE RISK
AREA.
THERE IS SOME CONCERN ABOUT WHETHER AN ADDITIONAL WATCH, OR PERHAPS
AN EXPANSION OF THE CURRENT WATCH, WILL BE NECESSARY FOR WEDNESDAY
NIGHT. AS THE FRONT SLOWLY SHIFTS SOUTH THROUGH THE REGION TOMORROW,
REDEVELOPMENT OF CONVECTION ALONG THE FRONT IS LIKELY. AGAIN, STORM
MOTIONS WILL BE PARALLEL TO THE FRONT, GIVING CONTINUED RISK OF
TRAINING STORMS AND LOCALLY HIGH RAINFALL AMOUNTS. AT THIS TIME,
THERE REMAINS ENOUGH UNCERTAINTY ABOUT THE LOCATION OF THE FRONT
WHEN THAT NEXT ROUND OF STORMS FIRES IN EARNEST. IT COULD BE IN OUR
FAR SOUTHERN AREAS, OR IT COULD BE JUST SOUTH OF OUR FORECAST AREA.
IT'S EVEN POSSIBLE THAT THE THREAT AFFECTS OUR SOUTHERN TIER
COUNTIES AND LINGERS INTO THURSDAY IF THE FRONT STRUGGLES TO FULLY
PUSH SOUTH OF OUR CWA. FOR THESE REASONS, I'D PREFER TO HOLD OFF ON
EXPANDING THE CURRENT WATCH OR ISSUING A NEW ONE TO AVOID CONFUSION
AND ALLOW DETAILS TO BECOME A LITTLE MORE CLEAR.
THE REMAINDER OF THE FORECAST HAS THE BASIC PATTERN OF UPPER RIDGING
TO OUR WEST AND TROUGHING OVER THE EASTERN CONUS CONTINUING. WE
WILL SEE SHORT WAVE ENERGY MOVING SOUTHEAST ON THE BACK SIDE OF THE
TROUGH AT TIMES THAT WILL BRING ADDITIONAL SHOWERS AN STORMS TO OUR
AREA FOR THE FRIDAY THROUGH TUESDAY PERIOD. TIMING OF THESE
FEATURES AND THE RESULTING CONVECTION IS OF COURSE UNCLEAR THIS FAR
OUT. TEMPERATURES FOR THURSDAY INTO SATURDAY LOOK TO BE A BIT BELOW
NORMAL, THEN THE REMAINDER OF THE PERIOD THROUGH TUESDAY WILL LIKELY
SEE TEMPERATURES NOT FAR FROM NORMAL FOR THIS TIME OF YEAR.
AVIATION
(18Z TAFS)
ISSUED AT 1252 PM EDT WED JUL 22 2026
WILL SEE PRIMARY AREA OF SHOWERS AND A FEW STORMS SHIFTING SOUTH,
SO PRIMARILY TRI/TYS EARLY ON AND MAINLY CHA LATE. WILL SEE VFR
EARLY WITH PERIODS OF MVFR OR LOWER WITH THE HEAVIER SHOWERS
AND/OR STORMS. CONFIDENCE IS NOT HIGH ON TRENDS LATER IN THE
PERIOD, BUT WILL CONTINUE WITH PREDOMINANT MVFR CONDITIONS FOR
LATER TONIGHT INTO THURSDAY AT TYS/CHA, WITH TYS LIKELY BACK TO
VFR LATE.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 72 86 71 87 / 70 60 30 70
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 85 69 86 / 70 40 20 60
OAK RIDGE, TN 67 85 67 86 / 40 20 10 50
TRI CITIES AIRPORT, TN 65 82 65 83 / 60 30 30 60
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR ANDERSON-BLOUNT
SMOKY MOUNTAINS-CAMPBELL-CLAIBORNE-COCKE SMOKY MOUNTAINS-
GRAINGER-HAMBLEN-HANCOCK-HAWKINS-JEFFERSON-JOHNSON-KNOX-
LOUDON-MORGAN-NORTH SEVIER-NORTHWEST BLOUNT-NORTHWEST
CARTER-NORTHWEST COCKE-NORTHWEST GREENE-ROANE-SCOTT TN-
SEVIER SMOKY MOUNTAINS-SOUTHEAST CARTER-SOUTHEAST GREENE-
SULLIVAN-UNICOI-UNION-WASHINGTON TN.
VA...FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR LEE-RUSSELL-SCOTT VA-
WASHINGTON VA-WISE.
DISCUSSION...CD
AVIATION...99
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