851
FXUS64 KMRX 272353
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
753 PM EDT MON JUL 27 2026
..NEW AVIATION
KEY MESSAGES
UPDATED AT 734 PM EDT MON JUL 27 2026
1. LOW POTENTIAL FOR RAIN AND THUNDER EARLY TOMORROW MORNING, MAINLY NORTH OF INTERSTATE 40.
THEN, ISOLATED TO SCATTERED THUNDERSTORMS IN THE AFTERNOON, WITH
MOST LIKELY TIME FOR A SEVERE STORM WITH DAMAGING WINDS BETWEEN 2
PM AND 6 PM EDT IN NORTHEASTERN TN AND SOUTHWESTERN VA.
2. HOT AND HUMID TOMORROW WITH HEAT INDICES REACHING INTO THE LOW 100SF,
AS HIGH AS 105F IN THE LOWER ELEVATIONS OF THE SOUTHERN VALLEY.
3. COLD FRONT YIELDS A DRIER AIR MASS WEDNESDAY THROUGH FRIDAY, WITH REGULAR
SUMMER TEMPERATURES AND HUMIDITY. RAIN CHANCES RETURN THIS
WEEKEND.
DISCUSSION
ISSUED AT 303 PM EDT MON JUL 27 2026
HUMID BUT OTHERWISE PLEASANT WEATHER THIS AFTERNOON. HUMIDITY WILL INCREASE SLIGHTLY TOMORROW,
WHILE WE WAIT FOR AN INCOMING COLD FRONT TO PROVIDE SOME MARGINAL
RELIEF AND KNOCK US BACK DOWN TO REGULAR SUMMER CONDITIONS. HEAT
INDICES IN THE SOUTHERN VALLEY TOMORROW AFTERNOON SHOULD ONCE
AGAIN CLIMB INTO THE LOW 100SF. WE WILL LIKELY BE NEAR HEAT
ADVISORY CRITERIA FOR PORTIONS OF THE VALLEY SOUTH OF INTERSTATE
40, AT OR AROUND 105F FEELS LIKE.
NOT FEELING VERY CONFIDENT ABOUT THE DEGREE TO WHICH WE SEE
SEVERE THUNDERSTORMS TOMORROW. CERTAINLY FROM A PARAMETER SPACE,
THE OVERALL NUMBERS ARE FAVORABLE BETWEEN SUPPORTIVE OVERALL
SHEAR, A COUPLE THOUSAND MLCAPE, AND ENOUGH TIME BETWEEN MORNING
CLOUD COVER AND DESTABILIZATION IN THE AFTERNOON HOURS. ON THE
OTHER HAND, OVERALL UPPER DYNAMICS AREN’T TOO FAVORABLE FOR SEVERE
WEATHER, THE MORNING REMNANTS OF THE STORMS UPSTREAM OF US MAY
INDUCE A BACKSIDE SINKING MOTION IN THE ATMOSPHERE, WHICH COULD
THEN INHIBIT UPDRAFT STRENGTH LATER IN THE DAY. THE HREF ONLY HAS
VERY LOW PROBABILITIES FOR STRONG UPDRAFT SPEEDS AND EXPERIMENTAL
AI GUIDANCE ALONG WITH TRADITIONAL CAMS ARE ALSO STRUGGLING TO
DEPICT WIDESPREAD CONVECTIVE COVERAGE. THERE’S A FEW MODEL S THAT
ARE ACTIVE, NAMELY THE EURO, RRFS, MPAS. THE MAIN THREAT WITH THIS
WILL BE DAMAGING WIND GUSTS WITH DISCRETE THUNDERSTORMS. I THINK
A TORNADO THREAT IS VERY LOW, BETWEEN PROBABLY TOO HIGH LCLS AND
TRENDING WEAKER LOW LEVEL HELICITY, THAT’S NOT AS BIG ON MY RADAR
AS YESTERDAY. MORE OBJECTIVE HREF AND EXPERIMENTAL GUIDANCE ALSO
KEEP PROBABILITIES REALLY LOW BUT THE ML NADOCAST IS STILL
CARRYING A 2% TORNADO RISK, SO AGAIN WOULDN’T RULE IT OUT
OUTRIGHT. OTHERWISE, IF STORMS ARE ABLE TO FIRE AND REACH THEIR
FULL POTENTIAL, THE ENVIRONMENT IS PRONE FOR DAMAGING WINDS 60 TO
70 MPH, FUELED BY MIDLEVEL DRY AIR AND PLENTY OF CAPE TO POWER
STRONG DOWNDRAFTS. SMALL TO MAYBE 1” HAIL AS WELL, THOUGH THE HIGH
FREEZING HEIGHTS OF JULY WILL BE MELTING ANY HAIL FALLING.
THERE’S POTENTIAL FOR MORNING SHOWERS AND MAYBE A THUNDERSTORM EARLY
TOMORROW MORNING, BUT GUIDANCE HAS BEEN CONSISTENT IN WEAKENING
THESE STORMS OR OUTRIGHT DISSIPATION. THEN THERE’S A NONZERO RISK
WE SEE SCATTERED CONVECTION IN A NORTHWEST TO SOUTHEAST DIRECTION
THROUGH THE DAY OVER SOUTHWEST VIRGINIA, BUT AGAIN, LOW
CONFIDENCE. THE UPPER JET LOOKING ITS BEST AT 06Z IN THE MORNING
IS NOT THE GREATEST SIGN FOR SIGNIFICANT SEVERE. OVERALL THE RISK
FOR SEVERE WEATHER IS LOW, AND IN THE NARROW TIMEFRAME OF SAY 2 PM
TO 6 PM EDT, MAINLY FOCUSED IN NORTHEASTERN TENNESSEE AND
SOUTHWESTERN VIRGINIA.
BEYOND TUESDAY WE’LL HAVE RAIN CHANCES DIMINISHING IN THE MOUNTAINS
OVERNIGHT WITH THE PASSAGE OF THE COLD FRONT, AND THEN A DRIER
AIR MASS LEADS TO REGULAR SUMMER VIBES THROUGH THE BACK HALF OF
THE WEEK WITH LIKELY DRY WEATHER. A NEW UPPER TROUGH ARRIVES IN
THE EASTERN US BY THIS SATURDAY, AND IT’S THIS TROUGH THAT WILL
ALSO BRING ABOUT THE NEXT BOUT OF RAIN CHANCES IN TIME FOR THE
WEEKEND.
AVIATION
(00Z TAFS)
ISSUED AT 734 PM EDT MON JUL 27 2026
SHOWERS AND THUNDERSTORMS MAY MOVE INTO THE REGION FROM THE
NORTHWEST LATE TONIGHT INTO THE EARLY MORNING HOURS MAINLY NEAR
TRI AND TYS BUT CONFIDENCE IS LOW THAT STORMS WILL MAKE IT THIS
FAR SOUTH. THERE IS HIGHER CONFIDENCE IN SOME RAIN NEAR TRI AND
TYS. TOMORROW THE BEST CHANCE FOR SHOWERS AND STORMS WILL BE IN
THE AFTERNOON/EVENING HOURS BUT CONFIDENCE IS LOW ON TIMING AND
COVERAGE OF SHOWERS/STORMS. VFR CONDITIONS ARE EXPECTED OUTSIDE OF
HEAVY RAIN. SOUTHWESTERLY WINDS WILL BE GUSTY TOMORROW AFTERNOON.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 75 95 74 90 / 0 50 30 10
KNOXVILLE MCGHEE TYSON AIRPORT, TN 73 93 71 87 / 10 80 60 0
OAK RIDGE, TN 73 93 70 87 / 10 60 40 0
TRI CITIES AIRPORT, TN 68 86 66 83 / 20 100 50 10
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
DISCUSSION...WELLINGTON
AVIATION...MCD
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