681
FXUS64 KMRX 171848
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
248 PM EDT MON AUG 17 2026
..NEW DISCUSSION
KEY MESSAGES
UPDATED AT 238 PM EDT MON AUG 17 2026
- SHOWERS AND STORMS WILL MOVE THROUGH THE AREA TODAY INTO THIS
EVENING, AND SOME WILL LIKELY BE STRONG TO SEVERE WITH DAMAGING
WINDS THE PRIMARY THREAT. LOCALIZED FLASH FLOODING IS ALSO
POSSIBLE ESPECIALLY NORTH.
- DRIER AND NOT QUITE AS HOT MID WEEK, THEN CHANCES FOR SHOWERS
AND STORMS INCREASE AGAIN THURSDAY INTO THE WEEKEND.
DISCUSSION
ISSUED AT 238 PM EDT MON AUG 17 2026
THE HEAT ADVISORY WILL BE ALLOWED TO CONTINUE THIS AFTERNOON. THE
SHOWERS AND STORMS WILL BRING AN ABRUPT END TO THE WORST OF TODAY'S
HEAT AS THEY MOVE THROUGH ANY GIVEN LOCATION.
THE WEAK COLD FRONT TO OUR WEST AND NORTHWEST WILL MOVE IN THIS
EVENING AND WILL BE NEAR OUR EASTERN BORDER BY EARLY TUESDAY. THE
ATMOSPHERE AHEAD OF THE FRONT FEATURES MLCAPE VALUES GENERALLY IN
THE 1500-2500 J/KG RANGE WITH STEEP LOW LEVEL LAPSE RATES AND
EFFECTIVE BULK SHEAR AROUND 20 TO 35 KT (HIGHER VALUES ARE ACROSS
THE NORTH). SIGNIFICANT DCAPE AND HIGH PWAT VALUES ARE ALSO IN
PLACE. CAMS GENERALLY SHOW THE CONVECTION ORGANIZING INTO A LINE OR
LINE SEGMENTS, AND DAMAGING STRAIGHT LINE WINDS ARE THE PRIMARY
THREAT. A VERY LOW, BUT NON-ZERO THREAT OF A BRIEF TORNADO SPIN UP
EXISTS AS WELL MAINLY ACROSS NORTHERN AREAS. VERY HEAVY RAINFALL
RATES CAN BE EXPECTED GIVEN PWAT VALUES CLIMBING TO AROUND 2 INCHES,
AND LOCALIZED FLASH FLOODING WILL BE POSSIBLE IN AREAS THAT SEE
PROLONGED OR REPEATED ROUNDS OF HEAVY RAINFALL ESPECIALLY ACROSS THE
NORTHERN HALF OF THE AREA WHERE THE GROUND IS STILL WET FROM THE
RECENT RAINS.
SURFACE HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT TUESDAY AND
WILL PROVIDE DRIER AND SLIGHTLY LESS HOT CONDITIONS FOR TUESDAY INTO
WEDNESDAY. WHILE IT WILL STILL BE ON THE HOT SIDE WITH HIGH
TEMPERATURES GENERALLY ABOVE SEASONAL NORMALS (ESPECIALLY
WEDNESDAY), LOWER HUMIDITY WILL KEEP HEAT INDEX VALUES LOWER THAN
RECENT DAYS.
BY THURSDAY AND FRIDAY MODELS SHOW ANOTHER SHORTWAVE OR MULTIPLE
SHORT WAVES MOVING IN WITH THE UPPER TROUGH OVER THE EASTERN CONUS
DEEPENING, AND ANOTHER WEAK COLD FRONT IS LIKELY TO PUSH THROUGH OUR
AREA SOMETIME IN THAT TIME FRAME AS WELL. HOWEVER, THE MODELS ARE
STILL STRUGGLING WITH THE DETAILS FOR THE LATER PERIODS. THE
ENSEMBLE APPROACH OF THE NBM HAS CHANCES FOR SHOWERS AND STORMS
INCREASING AGAIN FOR THURSDAY AND FRIDAY AND CONTINUING INTO
SATURDAY. SUNDAY AND MONDAY CURRENTLY LOOK DRIER AS THE TROUGH AXIS
SHIFTS TO OUR EAST AND SURFACE HIGH PRESSURE BUILDS IN, ALTHOUGH
CONFIDENCE IS NOT HIGH THAT FAR OUT. TEMPERATURES FOR THE WEEKEND
CURRENTLY LOOK TO BE NOT FAR EITHER SIDE OF NORMAL FOR THIS TIME OF
YEAR.
AVIATION
(18Z TAFS)
ISSUED AT 1239 PM EDT MON AUG 17 2026
SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH THIS AFTERNOON/EARLY
EVENING. WILL SEE VFR CONDITIONS FOR THE FIRST PART OF THE PERIOD,
OTHER THAN WITH ANY THUNDERSTORMS OR HEAVIER SHOWERS WHEN
CONDITIONS MAY DIP TO MVFR OR LOWER. BRIEF STRONG GUSTY WINDS WILL
ALSO BE ALSO POSSIBLE WITH STORMS WITH THE MOST LIKELY DIRECTION
FROM THE WEST OR NORTHWEST. LATE TONIGHT INTO EARLY TUESDAY MVFR
OR LOWER CONDITIONS ARE LIKELY AT TRI IN LOW CLOUDS AND/OR FOG,
WITH CONDITIONS LIKELY TO DIP AT LEAST BRIEFLY TO MVFR AT TYS.
BOTH LOCATIONS WILL RETURN TO VFR LATE IN THE PERIOD.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 74 93 69 95 / 30 0 0 0
KNOXVILLE MCGHEE TYSON AIRPORT, TN 73 89 68 92 / 60 10 0 0
OAK RIDGE, TN 71 89 66 91 / 40 0 0 0
TRI CITIES AIRPORT, TN 69 85 64 88 / 60 10 0 0
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
ANDERSON-BLEDSOE-BRADLEY-HAMILTON-KNOX-LOUDON-MARION-MCMINN-
MEIGS-MORGAN-NORTH SEVIER-NORTHWEST BLOUNT-NORTHWEST MONROE-
RHEA-ROANE-SEQUATCHIE-WEST POLK.
VA...NONE.
DISCUSSION...99
AVIATION...99
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