148
FXUS64 KMRX 122307
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
707 PM EDT TUE AUG 12 2025
..NEW AVIATION
DISCUSSION
ISSUED AT 141 PM EDT TUE AUG 12 2025
KEY MESSAGES:
1. HEAVY RAINFALL, HIGH RAINFALL RATES, AND LOCALIZED FLASH
FLOODING ARE POSSIBLE FROM THIS AFTERNOON THROUGH WEDNESDAY.
2. SCATTERED TO WIDESPREAD SHOWERS AND EMBEDDED STORMS.
3. REDUCED COVERAGE OF STORMS FOR THE LATTER HALF OF THE WEEK
THROUGH EARLY NEXT WEEK. RETURN TO HOT AND MUGGY CONDITIONS AS
WELL WITH HEAT INDICES INCREASING TO MID 90S TO NEAR 100 DEGREES
ACROSS MUCH OF THE TENNESSEE AND SEQUATCHIE VALLEYS.
DISCUSSION:
...LOCALIZED EXCESSIVE RAINFALL AND FLASH FLOODING POSSIBLE FROM
THIS AFTERNOON THROUGH WEDNESDAY...
A TROPICAL WAVE ACROSS THE NORTHERN GULF AND SOUTHWEST FLOW INTO
THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS WILL PULL ABUNDANT
TROPICAL MOISTURE INTO THE REGION. ENSEMBLE AND DETERMINISTIC
MODELS SHOW PWS INCREASING TO 2.1 TO POSSIBLY 2.3 INCHES WHICH IS
2-3 STANDARD DEVIATIONS ABOVE NORMAL OR 99TH PERCENTILE. THERE IS
ALSO WEAK 850MB MOISTURE TRANSPORT. A SERIES OF WEAK VORTS/SHEAR
AXIS WILL MOVE NORTH INTO THE PERIPHERY OF THE RIDGE INTO THE
APPALACHIANS ENHANCING CONVECTION. ALSO, LOCAL TERRAIN WILL ALSO
FOCUS POTENTIAL OF ENHANCED RAINFALL.
THE REFS AND HREF ARE IN AGREEMENT WITH THE POTENTIAL OF LOCALLY
HEAVY RAINFALL AND FLASH FLOODING. ENSEMBLE MEAN HAS A MORE
DEFINED 3"+ IN LOCALIZED AREAS. ON THE FENCE FOR ISSUING A FLASH
FLOOD WATCH. WOULD FEEL MUCH MORE CONFIDENT TO ISSUE A WATCH IS A
BOUNDARY WAS EVIDENT ACROSS THE REGION FOCUSING THE CONVECTION.
HELD OFF ISSUING A WATCH GIVEN COLLABORATION WITH THE SURROUNDING
WFOS BUT WILL SEND OUT DSS BRIEFING AND SPS HIGHLIGHTING THE
THREAT.
BESIDES THE POTENTIAL OF HEAVY RAINS, PLENTY OF TROPICAL MOISTURE
WILL KEEP SKY MOSTLY CLOUDY AND KEEP TEMPERATURES BELOW NORMAL
THROUGH MID-WEEK.
FOR THURSDAY, UPPER TROUGH WILL MOVE INTO THE AREA AND WEAKEN.
SCATTERED SHOWERS AND THUNDERSTORMS WILL BE EXPECTED WITH THE MAIN
CONCERN BEING LOCALIZED FLASH FLOODING.
FOR FRIDAY INTO EARLY NEXT WEEK, ENSEMBLE CLUSTER ANALYSIS SHOWS
INCREASING HEIGHTS WITH UPPER RIDGE BUILDING INTO THE MID-SECTION
OF THE NATION. END RESULT WILL BE DECREASING CHANCES OF MAINLY
AFTERNOON AND EARLY EVENING STORMS. MOST OF THE CONVECTION WILL BE
CONFINED TO THE HIGHER TERRAIN, ESPECIALLY FAR EAST TENNESSEE
MOUNTAINS AND SOUTHWEST NORTH CAROLINA WHICH IS FARTHER AWAY FROM
UPPER RIDGE AXIS.
ALSO TEMPERATURES WILL INCREASE WITH HIGHS IN THE LOWER AND MIDDLE
90S AND HEAT INDICES OF 95 TO 100 OVER MUCH OF THE TENNESSEE AND
SEQUATCHIE VALLEYS.
AVIATION
(00Z TAFS)
ISSUED AT 700 PM EDT TUE AUG 12 2025
SHOWERS AND STORMS THAT ARE CAUSING ONGOING FLOODING IN THE
CHATTANOOGA AREA CONTINUE TO BE THE MAIN AVIATION IMPACT WITH
IFR/LIFR LIKELY FOR AT LEAST THE NEXT HOUR OR TWO. ONCE THESE
STORMS LIKELY DECREASE, IMPROVEMENTS TO MVFR ARE EXPECTED, BUT
PERIODS OF IFR MAY RETURN OVERNIGHT INTO THE MORNING HOURS DUE TO
FOG. THE OTHER TERMINALS WILL LIKELY REMAIN VFR FOR THE NEXT
SEVERAL HOURS WITH REDUCTIONS TO MVFR LATE TONIGHT INTO THE EARLY
MORNING HOURS. ADDITIONAL SHOWERS AND STORMS ARE LIKELY AGAIN
DURING THE DAY TOMORROW WITH MVFR TO VFR.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 73 86 72 89 / 70 70 40 50
KNOXVILLE MCGHEE TYSON AIRPORT, TN 72 86 72 88 / 60 70 50 40
OAK RIDGE, TN 72 85 71 88 / 70 70 50 40
TRI CITIES AIRPORT, TN 69 83 69 84 / 80 70 60 60
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...DH
AVIATION...BW
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