904
FXUS64 KMRX 121719
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
119 PM EDT TUE AUG 12 2025
..NEW AVIATION
DISCUSSION
ISSUED AT 152 AM EDT TUE AUG 12 2025
KEY MESSAGES:
1. SCATTERED TO WIDESPREAD SHOWERS WITH LIMITED THUNDER CHANCES THIS
AFTERNOON AND TONIGHT. TROPICAL-LIKE HEAVY RAIN RATES COULD LEAD TO
INSTANCES OF FLASH FLOODING, PARTICULARLY WITHIN PORTIONS OF
SOUTHEAST TENNESSEE INTO SOUTHWEST NORTH CAROLINA.
2. ADDITIONAL SCATTERED SHOWERS AND STORMS EXPECTED WEDNESDAY.
LOCALLY HEAVY RAINFALL AND GUSTY WINDS POSSIBLE WITH A FEW STRONGER
STORMS.
3. WHILE DIURNAL CHANCES OF PRECIPITATION CONTINUE EACH DAY THROUGH
THE EXTENDED, THE BEST CHANCES WILL BE ACROSS HIGHER TERRAIN.
4. ABOVE NORMAL TEMPERATURES RETURN LATE WEEK AND INTO THE WEEKEND.
AFTERNOON HIGH TEMPERATURES IN THE LOW 90S WILL BECOME MORE COMMON
PLACE.
DISCUSSION:
A SUBTLE UPPER LOW ACROSS THE SOUTHEASTERN CONUS AND A NORTHERN
STREAM SHORTWAVE WILL PROMOTE STRONG AND DEEP MOISTURE ADVECTION
INTO THE REGION TODAY AND TONIGHT. LATEST NAMBUFR SOUNDINGS DEPICT
PWAT VALUES INCREASING NEAR THE DAILY MAX OF 2.2IN BASED OFF SPC
SOUNDING DATA FOR KBNA. THIS WILL BE ACCOMPANIED BY TALL AND SKINNY
CAPE PROFILES WITH MUCAPE AROUND 700-1300J/KG AND FREEZING LEVELS
NEAR 14.5KFT. THIS THERMODYNAMIC PROFILE IS SUPPORTIVE OF A DEEP
WARM RAIN PROCESS THAT COULD LEAD TO HEAVY RAIN RATES AND FLASH
FLOODING CONCERNS, ESPECIALLY SOUTH OF I-40 WHERE MID-LEVEL
VORTICITY AND EBWD WILL BE GREATEST IN CLOSER PROXIMITY TO THE
AFOREMENTIONED LOW.
BECAUSE OF THIS, WPC ERO HIGHLIGHTS PORTIONS OF THE AREA IN A SLIGHT
RISK. THE BIGGEST UNCERTAINTY IS CURRENTLY TIMING. THERE HAS BEEN
SOME SHIFT IN THE HIGHEST 6HR QPF AMOUNTS BEING MORE FOCUSED THROUGH
THE OVERNIGHT HOURS(6-12Z WEDNESDAY), WHICH WOULD MEAN INSTABILITY
WILL BE WANING AND COULD ALSO IMPACT RAIN RATES TO A CERTAIN EXTENT.
BECAUSE OF THIS UNCERTAINTY WILL HOLD OFF ON ANY FLASH FLOOD WATCH
FOR THE TIME BEING - JUST KNOW LOCALIZED TORRENTIAL DOWNPOURS COULD
LEAD TO INSTANCES OF FLASH FLOODING LATE TUESDAY AFTERNOON THROUGH
TUESDAY NIGHT. THE LATEST 00Z HREF SUITE DOES HAVE 90TH PERCENTILE
QPF SNEAKING INTO THE 3" RANGE IN THE SOUTHEAST TN AND SOUTHWEST NC
AND MAY BE A GOOD REPRESENTATION OF POTENTIAL 'LOCALLY HIGHER'
VALUES IN THE OCCURRENCE OF REPEATED OR TRAINING ACTIVITY. PER
LATEST CAMS, THIS ACTIVITY MAY LINGER UNTIL AROUND THE 12Z TIMEFRAME
WEDNESDAY MORNING.
IMPULSE TRANSLATING THROUGH MEAN FLOW ALOFT WILL PROMOTE ADDITIONAL
CONVECTION WED AFTERNOON. CONTINUED HIGH PWAT BETWEEN 1.8-2.0" WILL
MAINTAIN AN ISOLATED FLOOD THREAT. NAMBUFR SOUNDINGS ARE A BIT MORE
AGGRESSIVE WITH MLCAPE INCREASING TO NEAR 1500J/KG, WHICH WOULD BE
MORE SUPPORTIVE OF A FEW STRONGER STORMS WITH PRECIP LOADED
DOWNBURSTS LEADING TO GUSTY WINDS AS WELL.
DAILY SHOWER AND STORM CHANCES WILL PERSIST THROUGH THE REMAINDER OF
THE FORECAST PERIOD, THOUGH A CURRENT LACK OF NOTABLE SYNOPTIC
FEATURES WILL MEAN THE BEST CHANCE TO SEE ACTIVITY WILL BE ACROSS
HIGHER TERRAIN. H5 HEIGHT RISES LATE WEEK AND THROUGH THE WEEKEND
WILL ALSO TRANSLATE TO A RETURN OF ABOVE NORMAL TEMPERATURES. NOT
TOO SIGNIFICANT OF A HEATWAVE, BUT HIGH TEMPERATURES IN THE LOW 90S
WILL BECOME MORE WIDESPREAD.
AVIATION
(18Z TAFS)
ISSUED AT 110 PM EDT TUE AUG 12 2025
WILL HAVE SHOWERS AND THUNDERSTORMS AROUND THROUGH THE PERIOD, AND
TIMING AT ANY GIVEN SITE IS NOT POSSIBLE TO PIN DOWN. WILL CARRY A
LOT OF VCSH AND VCTS WITH A TEMPO AND PROB30 GROUP AT EACH SITE
TRYING TO TIME THE HIGHER PROBABILITY PERIODS. EXPECT VFR AND
MVFR CONDITIONS FOR THE MOST PART ALL SITES, BUT LOWER CONDITIONS
CAN BE EXPECTED IN HEAVIER PRECIPITATION.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 83 72 87 73 / 90 50 70 30
KNOXVILLE MCGHEE TYSON AIRPORT, TN 86 72 86 72 / 70 60 60 40
OAK RIDGE, TN 86 72 86 71 / 80 50 60 30
TRI CITIES AIRPORT, TN 85 69 83 69 / 70 70 70 40
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...KRS
AVIATION...KS
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