299
FXUS64 KMRX 191718
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
118 PM EDT SAT SEP 19 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 1232 PM EDT SAT SEP 19 2026
- WELL ABOVE NORMAL TEMPERATURES TO PERSIST INTO EARLY NEXT WEEK.
- EXPECT ISOLATED TO SCATTERED SHOWERS AND STORMS EACH AFTERNOON
TODAY THROUGH MONDAY, THEN CHANCES FOR SHOWERS AND STORMS WILL
BE HIGHER TUESDAY AND WEDNESDAY.
- A FEW STORMS MAY BE STRONG TO SEVERE WITH DAMAGING WINDS THE
PRIMARY THREAT EACH AFTERNOON TODAY THROUGH AT LEAST MONDAY.
LOCALIZED FLOODING WILL BE POSSIBLE EACH DAY THROUGH WEDNESDAY
AS WELL.
- COOLER CONDITIONS ARE EXPECTED TO ARRIVE BY THE LATTER HALF OF
THE COMING WEEK.
DISCUSSION
ISSUED AT 142 AM EDT SAT SEP 19 2026
SATURDAY AND SUNDAY WILL FEATURE DECREASING HEIGHTS ALOFT AS THE
UPPER RIDGE, CENTERED OVER THE ARKLATEX REGION, BEGINS TO BREAK
DOWN. THAT WILL PLACE THEE SOUTHERN APPALACHIAN REGION ON THE
PERIPHERY OF THE RETREATING RIDGE, ALLOWING FOR A MIX OF DIURNALLY
FORCED CONVECTION AND THUNDERSTORM COMPLEXES MOVING IN FROM THE
NORTHWEST IN THIS "RING OF FIRE" TYPE SETUP. MUCH OF THE CWA IS IN A
MARGINAL RISK AREA FOR A DAMAGING WIND THREAT TOMORROW, WHILE ONLY
IN A GENERAL THUNDER AREA ON SPC'S DAY 3 OUTLOOK. I WOULDN'T BE
SURPRISED TO SEE THAT EXPANDED ON SUNDAY. THE THERMODYNAMIC SETUP
FOR BOTH SATURDAY AND SUNDAY LOOKS SIMILAR TO TODAY, THAT IS TO SAY
DCAPE VALUES IN THE 1,000 - 1,200 J/KG RANGE, FAVORABLE LAPSE RATES,
AND MLCAPE NORTH OF 1,500 J/KG. AS SUCH, IT WOULD NOT BE HARD TO
IMAGINE A SCENARIO WHERE A HANDFUL OF SIG WX ADVISORIES AND A MAYBE
A COUPLE OF SEVERE THUNDERSTORM WARNINGS ARE ISSUED.
LOOKING AHEAD TO MONDAY AND TUESDAY, AFTERNOON SHOWERS AND STORMS
REMAIN IN THE FORECAST AS THE RIDGE CONTINUES TO BREAK DOWN AND AN
UPPER LOW, ONCE OVER THE INTERMOUNTAIN WEST, SHIFTS EAST ACROSS THE
PLAINS AND INTO THE GREAT LAKES REGION SUNDAY THROUGH TUESDAY.
TEMPERATURES WILL REMAIN WELL ABOVE NORMAL THROUGH THIS TIME.
TUESDAY NIGHT INTO WEDNESDAY THE UPPER LOW DEEPENS OVER THE GREAT
LAKES REGION AND LEADS TO A PATTERN CHANGE CHARACTERIZED BY MUCH
MORE NOTABLE TROUGHING OVER THE EASTERN CONUS AS OPPOSED TO HIGH
PRESSURE. IN FACT, WE MAY HAVE A LEGITIMATE COLD FRONT PASSAGE NEXT
WEDNESDAY BENEATH THE UPPER TROUGH/LOW. IN ADDITION TO INCREASED
CHANCES FOR SHOWERS AND STORMS THIS PATTERN WILL BRING, TEMPERATURES
WILL BEGIN COOLING OFF BEHIND ON THE BACKSIDE OF THE TROUGH. DRIER
AND COOLER CONDITIONS EXPECTED ON THURSDAY AND FRIDAY. HIGH
TEMPERATURES WILL BE IN THE 70S/80S AS OPPOSED TO THE 80S/90S.
OVERNIGHT LOWS WILL BE IN THE 50S/60S INSTEAD OF THE 60S/70S. SO
HOLD ON FOR A FEW MORE DAYS OF HEAT, RELIEF IS ON THE WAY!
LASTLY, UNTIL WE SEE A RELIEF IN TEMPS, CHATTANOOGA WILL CONTINUE TO
BUILD ONTO THEIR RECORD STREAK OF 90 DEGREES OR HIGHER. THEY
CURRENTLY SIT AT 45 DAYS, WITH SEVERAL MORE DAYS LIKELY TO ADD TO
THE STREAK. THE FIRST DAY WHERE THE OFFICIAL FORECAST IS BELOW 90 IS
NEXT WEDNESDAY. IF THEY HOLD ON TO 90 THROUGH TUESDAY, THAT WOULD
BRING THE STREAK UP TO 50 DAYS.
AVIATION
(18Z TAFS)
ISSUED AT 1232 PM EDT SAT SEP 19 2026
ISOLATED TO SCATTERED SHOWERS AND STORMS WILL BE AROUND THIS
AFTERNOON, AND WILL INCLUDE PROB30 THUNDER GROUPS ALL THREE
SITES. THE OTHER CONCERN WILL BE POSSIBLE FOG DEVELOPMENT TONIGHT
MAINLY TRI. IF RAIN OCCURS AT TRI THIS AFTERNOON/EARLY EVENING THEN
THE CHANCES FOR SIGNIFICANT FOG WILL INCREASE, BUT THAT IS STILL
UNKNOWN AT THIS TIME. FOR NOW WILL ADD SEVERAL HOURS OF MVFR FOG
LATE TONIGHT AT TRI, BUT DENSE FOG IS A POSSIBILITY AGAIN.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 72 96 72 96 / 10 20 10 40
KNOXVILLE MCGHEE TYSON AIRPORT, TN 70 93 70 92 / 20 20 10 40
OAK RIDGE, TN 70 92 69 92 / 20 20 10 50
TRI CITIES AIRPORT, TN 66 88 66 88 / 30 40 10 50
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...CD
AVIATION...99
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