715
FXUS64 KMRX 271705
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
105 PM EDT FRI JUN 27 2025
..NEW AVIATION
SHORT TERM
(TODAY AND TONIGHT)
ISSUED AT 1219 AM EDT FRI JUN 27 2025
KEY MESSAGES:
1. SCATTERED SHOWERS AND STORMS MAINLY DURING THE AFTERNOON HOURS.
LOW PROBABILITY OF SEVERE THUNDERSTORMS WITH GUSTY WIND, HEAVY RAIN
RATES, AND FREQUENT LIGHTNING.
2. HEAT AND HUMIDITY REMAIN, BUT SLIGHTLY LOWER TEMPERATURES BELOW
HEAT ADVISORY CRITERIA.
DISCUSSION:
A WEAKNESS IN THE UPPER RIDGE DEVELOPS ACROSS THE REGION WHICH WILL
RESULT IN SLIGHTLY LOWER MAX TEMPERATURES (ALTHOUGH STILL HOT AND
HUMID SUMMER CONDITIONS) THAT WILL BE LOWER THAN HEAT ADVISORY
CRITERIA. STILL, HEAT INDEX VALUES APPROACHING 100F WILL BE PROBABLE
ACROSS THE SOUTHERN VALLEY BETWEEN CHATTANOOGA AND KNOXVILLE. IT
WILL BE VITAL TO CONTINUE TO PRACTICE HEAT SAFETY ACROSS THE REGION,
ESPECIALLY IF OUTDOORS FOR PROLONGED PERIODS OF TIME.
IN ADDITION TO THE HEAT, THIS WEAKNESS IN THE RIDGE WILL SUPPORT
ADDITIONAL SCATTERED SHOWERS AND THUNDERSTORMS THIS AFTERNOON.
COVERAGE IS EXPECTED TO BE MORE THAN PREVIOUS DAYS, ALTHOUGH NOT
EVERYONE IS GUARANTEED TO SEE RAINFALL. RAP MODEL GUIDANCE INDICATES
MLCAPE AROUND 3000 J/KG AND DCAPE BETWEEN 800-1000 J/KG WILL
CONTINUE TO SUPPORT A FEW STRONG TO SEVERE THUNDERSTORMS WITH STRONG
DOWNBURST POTENTIAL. CONVECTION WILL LIKELY DEVELOP FIRST ALONG THE
HIGHER ELEVATIONS OF THE MOUNTAINS AND PLATEAU BETWEEN NOON AND 2PM
DUE TO CONVERGENCE ALONG THE TERRAIN VIA DIFFERENTIAL HEATING. AS
THESE OUTFLOW BOUNDARIES PROGRESS OUTWARD, CONVECTION WILL BECOME
MORE LIKELY ACROSS THE VALLEY LOCATIONS BETWEEN 4PM AND 6PM. PW
VALUES AROUND 1.8 TO 2.0 INCHES WILL SUPPORT SOME HEAVY RAIN RATES
AND THE POTENTIAL OF SOME ISOLATED FLOODING OF LOW LYING AREAS.
CONVECTIVE COVERAGE WILL BEGIN TO DIMINISH WITH THE LOSS OF DAYTIME
HEATING. AREAS OF FOG WILL BE LIKELY OVERNIGHT FOR AREAS THAT
RECEIVE RAINFALL DURING THE DAY.
LONG TERM
(SATURDAY THROUGH FRIDAY)
ISSUED AT 1219 AM EDT FRI JUN 27 2025
KEY MESSAGES:
1. HIGHER RAIN CHANCES AND SLIGHTLY LOWER DAYTIME TEMPERATURES
THROUGH THE WEEKEND INTO THE EARLY PART OF THE WEEK. ISOLATED STRONG
OR SEVERE STORMS AND LOCALIZED FLASH FLOODING ARE POSSIBLE EACH DAY.
FLOODING RISK INCREASES MONDAY/TUESDAY.
2. A COLD FRONT APPROACHES THE AREA TUESDAY, WITH THE POSSIBILITY OF
LESS PRECIPITATION COVERAGE WEDNESDAY AND THURSDAY IF THE FRONT
MAKES IT ALL THE WAY ACROSS OUR AREA AND MOVES SOUTHEAST OF THE
REGION.
DISCUSSION:
THE WEAKNESS IN THE RIDGE THIS WEEKEND WILL CONTINUE TO PRODUCE MORE
WIDESPREAD DIURNAL CONVECTION EACH AFTERNOON AND EVENING. WITH
MLCAPE AROUND 2500 TO 3000 J/KG, A FEW STRONG TO SEVERE PULSE
THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON WITH THE PRIMARY RISK
BEING DAMAGING WINDS. PW VALUES WILL BE VARIABLE BUT GENERALLY RANGE
FROM 1.8 TO 2.0 INCHES THIS WEEKEND. THIS WILL PRODUCE SOME MODERATE
TO HEAVY RAINFALL RATES WITH LOCALIZED FLOODING.
MODEL AND ENSEMBLE GUIDANCE INDICATES MORE TROPICAL MOISTURE AHEAD
OF THE FRONTAL BOUNDARY EARLY NEXT WEEK. THIS WILL BRING PW VALUES
INTO THE 2.0 TO 2.2 INCH RANGE ACROSS THE FORECAST AREA BY MONDAY
AND TUESDAY AHEAD OF AN UPPER-LEVEL TROUGH AND ASSOCIATED COLD
FRONT. THESE HIGHER PW VALUES AND TROPICAL AIRMASS WILL PROMOTE VERY
HEAVY RAINFALL RATES OF 3 TO 4+ INCHES PER HOUR. ANY TRAINING OR
SLOW MOVING CONVECTION WILL LIKELY LEAD TO FLASH FLOODING CONCERNS,
ESPECIALLY FOR URBAN AREAS WITH POOR RUNOFF. THE ISOLATED SEVERE
RISK WILL CONTINUE, MAINLY FOR SOME ISOLATED DOWNBURST WINDS.
FREQUENT LIGHTNING WILL ALSO BE EXPECTED WITH ANY THUNDERSTORM.
THIS FRONT IS EXPECTED TO SLOWLY MOVE SOUTHEAST ACROSS THE REGION
WITH DRIER AIR ARRIVING FROM THE NORTHWEST. WE EXPECTED TO BE MOSTLY
DRY BY WEDNESDAY, BUT THE FRONT MAY NOT FULLY CLEAR OUR SOUTHERN
AREAS. THIS WILL KEEP SOME LOW POPS IN FOR WEDNESDAY, MAINLY ACROSS
SOUTHEAST TENNESSEE AND SOUTHWEST NORTH CAROLINA. ENSEMBLE MEMBERS
DRY OUT FOR MOST OF THE REGION BY THURSDAY AND FRIDAY AS THE FRONT
IS EXPECTED TO FINALLY MOVE SOUTH OF THE REGION.
AVIATION
(18Z TAFS)
ISSUED AT 103 PM EDT FRI JUN 27 2025
SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS ANTICIPATED THIS
AFTERNOON INTO THE EVENING. HAVE TRIED TO CONVEY THE BEST TIMING
FOR THOSE THAT COULD AFFECT THE TAF SITES. TOMORROW MORNING FOG
AND LOW CEILINGS WILL BE POSSIBLE ESPECIALLY FOR THOSE SITES THAT
EXPERIENCE RAINFALL LATER TODAY. CONFIDENCE IS FAIRLY HIGH FOR
KTRI TO DROP AGAIN SATURDAY MORNING.
PRELIMINARY POINT TEMPS/POPS
CHATTANOOGA AIRPORT, TN 71 92 72 93 / 20 60 20 50
KNOXVILLE MCGHEE TYSON AIRPORT, TN 70 90 70 91 / 30 70 20 50
OAK RIDGE, TN 69 90 70 91 / 30 60 20 50
TRI CITIES AIRPORT, TN 67 88 67 88 / 30 70 30 60
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...
LONG TERM....JB
AVIATION...WELLINGTON
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