717
FXUS64 KMRX 190549
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
149 AM EDT SAT SEP 19 2026
..NEW DISCUSSION, AVIATION
KEY MESSAGES
UPDATED AT 142 AM EDT SAT SEP 19 2026
- WELL ABOVE NORMAL TEMPERATURES TO PERSIST THROUGH EARLY NEXT
WEEK. HEAT INDICES WILL REMAIN IN THE UPPER 90S TO LOWER 100S
ACROSS THE CENTRAL EAST TN AND SOUTHERN TN VALLEY THROUGH
MONDAY.
- TEMPS COOLING TOWARDS NORMAL AT THE END OF THE FORECAST PERIOD,
MID TO LATE NEXT WEEK.
- INCREASING RAIN CHANCES THIS WEEKEND INTO NEXT WEEK, SIMILAR TO
A TYPICAL SUMMER PATTERN. BETTER CHANCES FOR MORE WIDESPREAD
RAIN BY TUE/WED.
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
(06Z TAFS)
ISSUED AT 142 AM EDT SAT SEP 19 2026
ISOLATED SHOWERS HAVE FORMED ACROSS PORTIONS OF EASTERN TN ALONG
AN OUTFLOW BOUNDARY. THESE SHOWERS SHOULD AVOID OUR TERMINALS AND
DISSIPATE SHORTLY AFTER ISSUANCE. SKIES WILL SCATTER OVERNIGHT.
OUR PRIMARY CONCERN THIS EVENING IS THE REDEVELOPMENT OF FOG, ESPECIALLY
IN THE NORTH. FOG HAS ALREADY RETURNED AT TRI WHERE I'VE ADDED
PREVAILING MVFR BR WITH A TEMPO FOR LOWER VSBY AND CIGS PRIOR TO
SUNRISE. THE SOUTHERN EXTEND OF FOG IS A BIT UNCERTAIN BUT I HAVE
OPTED TO KEEP IT OUT AT TYS. ISOLATED TO SCATTERED SHOWERS AND
STORMS RETURN THIS AFTERNOON. I HAVE KEPT OUT ANY PROB30S GIVEN
THE VARIANCE IN HI-RES GUIDANCE WITH RESPECT TO COVERAGE. ODDS
ARE WE'LL NEED TO ADD PROB30S WITH THE 12Z TAF SET. WINDS WILL
GENERALLY BE LIGHT AND VARIABLE THROUGHOUT THE PERIOD.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 98 72 96 71 / 40 20 30 20
KNOXVILLE MCGHEE TYSON AIRPORT, TN 94 70 92 69 / 30 20 30 30
OAK RIDGE, TN 93 70 92 68 / 30 10 20 30
TRI CITIES AIRPORT, TN 88 66 87 65 / 30 20 50 30
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...CD
AVIATION...BH
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