943
FXUS64 KMRX 032342
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
742 PM EDT THU SEP 3 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 739 PM EDT THU SEP 3 2026
- VERY HOT CONDITIONS ARE EXPECTED THROUGH THE REST OF THE WEEK
WITH HIGHS REACHING WELL INTO THE 90S AND HEAT INDEX VALUES
APPROACHING OR EXCEEDING 100 FOR MOST PLACES OUTSIDE THE HIGHER
ELEVATIONS. TAKE FREQUENT BREAKS AND DRINK PLENTY OF WATER WHEN
OUTDOORS THIS WEEK!
- TEMPERATURES WILL GRADUALLY MODERATE SOME THROUGH THE WEEKEND
WITH A RETURN OF ISOLATED TO SCATTERED SHOWERS AND STORMS.
- A FEW STORMS FRIDAY AFTERNOON/EVENING MAINLY NORTH AND THEN
INCLUDING THE REMAINDER OF THE AREA SATURDAY MAY BECOME STRONG
TO SEVERE, WITH DAMAGING WIND GUSTS THE PRIMARY THREAT.
DISCUSSION
ISSUED AT 123 PM EDT THU SEP 3 2026
THERE ARE TWO MAIN TALKING POINTS FOR THE FORECAST PERIOD. THE FIRST
IS THE CONTINUED HEAT ACROSS THE REGION, DRIVEN BY A STRONG UPPER
RIDGE LOCATED OVERHEAD. AND THE SECOND IS THE CHANCES FOR SEVERE
STORMS ON SATURDAY AS THE RIDGE SHIFTS WESTWARD...BRIEFLY.
FIRST OF ALL, THE UPPER RIDGE RESPONSIBLE FOR OUR HEATWAVE THIS WEEK
WILL REMAIN SITUATED OVER THE SOUTHERN APPALACHIAN REGION TODAY AND
FRIDAY. DETERMINISTIC GUIDANCE SHOWS HIGHS IN THE 95-100 DEGREE
RANGE THROUGHOUT THE VALLEY THIS AFTERNOON AND AGAIN ON FRIDAY.
DEWPOINTS WILL REMAIN IN THE UPPER 60S TO LOW 70S BOTH DAYS,
RESULTING IN AFTERNOON HEAT INDEX VALUES IN THE 100-105 DEGREE
RANGE. MODEL GUIDANCE SHOWS THE RIDGE BEING ALMOST PERFECTLY
CENTERED OVER THE MRX FORECAST AREA DURING THE DAY TOMORROW, WITH
AN EXPANSION IN WARMER H85 TEMPS NOTED. I COULD SEE US EKING OUT
ANOTHER DEGREE OR TWO ABOVE WHAT THE NBM GUIDANCE IS SHOWING,
WHICH IS ALSO SUPPORTED BY SOME GUIDANCE SOURCES INCLUDING THE
ECMWF. IF THAT HAPPENS, ADVISORY CRITERIA WOULD DEFINITELY BE
REACHED FURTHER NORTH. SINCE WE'RE GOING TO BE CLOSE TO ADVISORY
CRITERIA TODAY IN AREAS OUTSIDE THE HEAT ADVISORY THAT WAS ISSUED
YESTERDAY, AND THERE'S A DECENT SHOT WE'D NEED IT TOMORROW, I WENT
AHEAD AND EXPANDED IT EFFECTIVE THIS AFTERNOON. THE RIDGE SHIFTS
WEST ON SATURDAY, ALLOWING A "COLD" FRONT TO MOVE THROUGH, AND
REMAINS CENTERED OVER THE GREAT PLAINS THROUGH TUESDAY BEFORE
SHIFTING BACK EAST AGAIN. IN OTHER WORDS, THE HEAT RETURNS NEXT
WEEK IT SEEMS. LASTLY, I'VE INCLUDED A CLIMATE SECTION BELOW TO
HIGHLIGHT SOME POTENTIAL RECORDS THAT ARE IN JEOPARDY IN THE
COMING DAYS.
WITH REGARDS TO SEVERE CHANCES ON SATURDAY, A DEEP TROUGH DIGS OVER
THE WEST COAST FRIDAY INTO SATURDAY, ALLOWING THE RIDGE TO SHIFT
WEST TO THE PLAINS AND A TROUGH TO STRENGTHEN ALONG THE EASTERN
SEABOARD. THIS WILL SEND AT LEAST ONE IMPULSE THROUGH THE OHIO
VALLEY, SOUTHERN APPALACHIANS, AND INTO THE CAROLINAS ON SATURDAY
AND PUSH A COLD FRONT THROUGH THE REGION. FORECAST SOUNDINGS SHOW
SOME RATHER EXTREME INSTABILITY VALUES OVER THE FORECAST AREA ON
SATURDAY AFTERNOON, CHARACTERIZED BY MIXED LAYER CAPE VALUES OF
2,500 TO 4,000 J/KG, COINCIDENT WITH MID LEVEL LAPSE RATES OF OVER
6.5 C/KM IN SOME CASES. ANY STORM THAT CAN GET A SUSTAINED UPDRAFT
GOING IN THAT ENVIRONMENT WILL HAVE LITTLE TO NO ISSUES BECOME
STRONG TO SEVERE. DOWNBURSTS AND EVEN LARGE HAIL WOULD BE ON THE
TABLE, DESPITE FREEZING LEVELS ABOVE 13,000 FT. THANKFULLY, SHEAR IS
ON THE LOW-END OF THE SPECTRUM IN TERMS OF SUPPORTING ORGANIZED
CONVECTION, SO COVERAGE IS EXPECTED TO BE SOMEWHAT SPARSE.
THE "COLD" FRONT KNOCKS HIGHS DOWN INTO THE 80S TO 90S FOR SUNDAY
THROUGH TUESDAY, BUT AS I MENTIONED ABOVE THE RIDGE SHIFTS BACK EAST
BY MID-WEEK NEXT WEEK SO I SUSPECT WE'LL SEE A RETURN OF QUITE WARM
TEMPERATURES.
---- CLIMATE SECTION ----
I WANTED TO HIGHLIGHT THE CHATTANOOGA AREA IN THE CLIMATE SECTION.
CURRENTLY THEY'RE SITTING AT 30 STRAIGHT DAYS (VALID 9/2/2026) OF
HIGHS AT/ABOVE 90 DEGREES, WHICH IS TIED FOR 4TH PLACE. HIGH
TEMPERATURES ARE FORECAST TO REMAIN AT/ABOVE 90 DEGREES THROUGH THE
FORECAST PERIOD. UNLESS SOMETHING GOES OFF THE RAILS AND A
THUNDERSTORM IMPACTS THEIR MAX TEMPS ONE DAY, THERE'S A VERY GOOD
CHANCE THEY BREAK THE ALL TIME RECORD OF CONSECUTIVE DAYS AT/ABOVE
90 NEXT WEEK. CONTRAST THIS WITH TRI-CITIES AND KNOXVILLE, WHICH
DON'T HAVE ACTIVE STREAKS THAT EVEN RANK IN THE TOP 50.
BELOW ARE SOME TABLES THAT HIGHLIGHT DAILY RECORD HIGHS FOR ALL 4
CLIMATE SITES THROUGH NEXT WEEK, AS WELL AS SOME INFORMATION ON THE
90 DEGREE DAY STREAK FOR CHATTANOOGA SPECIFICALLY.
CHATTANOOGA 90 DEGREE DAY STREAK
RANK DAYS ENDING DATE
1 38 08-02-1993
2 32 08-29-2007
3 31 07-21-1954
4 30 09-02-2026
5 29 08-16-2010
DAILY RECORD HIGH MAXIMUM TEMPERATURES
DATE CHATTANOOGA KNOXVILLE TRI-CITIES OAK RIDGE
09-03 100(1954) 98(2011) 96(2011) 99(2011)
09-04 102(1954) 101(1954) 99(1954) 100(1954)
09-05 104(1925) 103(1954) 99(1954) 102(1954)
09-06 103(1925) 101(1954) 100(1954) 102(1954)
09-07 104(1925) 102(1925) 100(1954) 99(1954)
09-08 100(1925) 96(1941) 92(2002) 95(1999)
09-09 102(1925) 100(1925) 95(1954) 97(1954)
AVIATION
(00Z TAFS)
ISSUED AT 739 PM EDT THU SEP 3 2026
RADAR SHOULD REMAIN QUIET OVERNIGHT. TONIGHT PATCHY FOG AGAIN
POSSIBLE AT KTRI, THOUGH DEWPOINT DEPRESSIONS ARE A LITTLE LARGER
AT THE MOMENT THAN THIS TIME YESTERDAY. FOG IS LIKELY GETTING A
BOOST FROM COLD WATER RELEASES FROM SOUTH HOLSTON. TOMORROW
ISOLATED TS ACTIVITY IS POSSIBLE, BUT VERY LOW CONFIDENCE (10 TO
20%) ON IF ANY ACTIVITY IMPACTS THE TERMINALS, MAINLY BETWEEN 18Z
AND 03Z, SO KEPT A MENTION OUT OF THE TAFS FOR NOW. WINDS WILL
REMAIN LIGHT, UNLESS A STRONG STORM COLLAPSES OVER OR IMMEDIATELY
ADJACENT TO AN AIRFIELD.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 75 99 76 98 / 0 10 0 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 74 97 75 96 / 0 10 0 20
OAK RIDGE, TN 74 98 74 96 / 0 10 10 30
TRI CITIES AIRPORT, TN 70 95 70 91 / 0 10 10 50
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ FRIDAY FOR ANDERSON-
BLEDSOE-BRADLEY-CAMPBELL-CLAIBORNE-GRAINGER-HAMBLEN-
HAMILTON-HANCOCK-HAWKINS-JEFFERSON-KNOX-LOUDON-MARION-
MCMINN-MEIGS-MORGAN-NORTH SEVIER-NORTHWEST BLOUNT-NORTHWEST
COCKE-NORTHWEST GREENE-NORTHWEST MONROE-RHEA-ROANE-SCOTT TN-
SEQUATCHIE-UNION-WEST POLK.
VA...NONE.
DISCUSSION...CD
AVIATION...WELLINGTON
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