078
FXUS64 KMRX 271741
AFDMRX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MORRISTOWN TN
141 PM EDT FRI JUN 27 2025
..NEW SHORT TERM, LONG TERM
SHORT TERM
(THIS AFTERNOON THROUGH SATURDAY)
ISSUED AT 134 PM 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 ESPECIALLY THIS AFTERNOON, BUT SLIGHTLY
BELOW HEAT ADVISORY CRITERIA.
DISCUSSION:
A WEAKNESS IN THE UPPER RIDGE ACROSS THE REGION WILL RESULT IN
SLIGHTLY LOWER MAX TEMPERATURES (ALTHOUGH STILL HOT AND HUMID SUMMER
CONDITIONS) AND WE SHOULD GENERALLY STAY BELOW HEAT ADVISORY
CRITERIA. STILL, HEAT INDEX VALUES AROUND 100 ARE OCCURRING IS SOME
VALLEY LOCATIONS MAINLY IN THE SOUTHERN/CENTRAL VALLEY . IT WILL BE
VITAL TO CONTINUE TO PRACTICE HEAT SAFETY ACROSS THE REGION,
ESPECIALLY IF OUTDOORS FOR PROLONGED PERIODS OF TIME. TOMORROW
SHOULD BE A BIT LESS HOT THAN TODAY.
THE WEAKNESS IN THE RIDGE WILL ALSO ALLOW MORE NUMEROUS MAINLY
DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS THAN HAVE BEEN SEEN IN
RECENT DAYS, ALTHOUGH NOT EVERYONE IS GUARANTEED TO SEE RAINFALL.
MLCAPE VALUES OF 2000 TO 3000+ J/KG AND DCAPE BETWEEN 800-1000 J/KG
THIS AFTERNOON WILL CONTINUE TO SUPPORT A FEW STRONG TO SEVERE
THUNDERSTORMS WITH DAMAGING DOWNBURST POTENTIAL. PW VALUES AROUND
1.4 TO 1.8 INCHES WILL SUPPORT SOME HEAVY RAIN RATES AND THE
POTENTIAL OF SOME ISOLATED FLOODING OF LOW LYING AREAS. CONVECTIVE
COVERAGE WILL BEGIN TO DIMINISH THIS EVENING WITH THE LOSS OF
DAYTIME HEATING.
FOR TOMORROW MODELS SHOW LESS INSTABILITY THAN TODAY BUT PW VALUES
WILL TICK UP MORE INTO THE 1.5 TO 1.9 INCH RANGE. WE WILL SEE
SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS AGAIN ESPECIALLY
WITH PEAK HEATING, AND WHILE THE STRONG TO SEVERE STORM THREAT WILL
BE LOWER GIVEN THE MORE LIMITED INSTABILITY (HREF SHOWS MEAN MUCAPES
GENERALLY LESS THAN 2000 J/KG), A FEW STORMS MAY STILL BECOME STRONG
TO MARGINALLY SEVERE WITH DAMAGING WIND GUSTS THE PRIMARY SEVERE
THREAT. IN ADDITION, GIVEN THE PLENTIFUL MOISTURE THERE WILL
CONTINUE TO BE A THREAT OF LOCALIZED FLOODING.
LONG TERM
(SATURDAY NIGHT THROUGH NEXT FRIDAY)
ISSUED AT 134 PM EDT FRI JUN 27 2025
KEY MESSAGES:
1. HIGHER RAIN CHANCES INTO THE EARLY PART OF THE WEEK. ISOLATED
STRONG OR SEVERE STORMS AND LOCALIZED FLASH FLOODING ARE POSSIBLE
EACH DAY, WITH THE FLOODING RISK HIGHEST MONDAY/TUESDAY.
2. A COLD FRONT APPROACHES THE AREA TUESDAY, WITH THE POSSIBILITY OF
LESS PRECIPITATION COVERAGE WEDNESDAY THROUGH FRIDAY IF THE FRONT
MOVES SOUTHEAST OF THE REGION.
DISCUSSION:
THE WEAKNESS IN THE RIDGE WILL CONTINUE TO PRODUCE QUITE A BIT OF
MAINLY DIURNALLY DRIVEN CONVECTION SUNDAY AFTERNOON AND EVENING. A
FEW STRONG TO SEVERE PULSE THUNDERSTORMS WILL BE POSSIBLE AGAIN IN
THE AFTERNOON WITH THE PRIMARY RISK BEING DAMAGING WINDS. PW VALUES
WILL GENERALLY RANGE FROM 1.7 TO 1.9 INCHES SUNDAY. THIS WILL
PRODUCE SOME MODERATE TO HEAVY RAINFALL RATES WITH A THREAT OF
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 1.8 TO 2.2 INCH RANGE ACROSS THE FORECAST AREA BY MONDAY
AND TUESDAY AHEAD OF AN UPPER-LEVEL TROUGH AND ASSOCIATED COLD
FRONT. THIS VERY MOIST AIRMASS WILL PROMOTE VERY HEAVY RAINFALL
RATES LIKELY EXCEEDING 3 INCHES PER HOUR IN HEAVIER DOWNPOURS.
ANY TRAINING OR SLOW MOVING CONVECTION WILL LIKELY LEAD TO FLASH
FLOODING CONCERNS, ESPECIALLY FOR URBAN AREAS WITH POOR RUNOFF AND
OTHER FLOOD PRONE AREAS. THE ISOLATED SEVERE RISK WILL CONTINUE
AS WELL, MAINLY FOR SOME ISOLATED DOWNBURST WINDS.
THE COLD FRONT IS EXPECTED TO SLOWLY MOVE SOUTHEAST ACROSS THE
REGION TUESDAY AND/OR TUESDAY NIGHT WITH DRIER AIR ARRIVING FROM
THE NORTHWEST. MUCH OF THE MODEL DATA CONTINUES TO SUGGEST THE
FRONT WILL MAKE IT TO OUR SOUTHEAST BEFORE STALLING, BUT AS IS
OFTEN THE CASE WITH THESE WEAK SUMMERTIME FRONTS THERE IS STILL
SIGNIFICANT UNCERTAINTY ABOUT EXACTLY HOW FAR IT WILL PROGRESS.
RIGHT NOW, WE EXPECT IT TO BE DRIER ACROSS OUR AREA WEDNESDAY,
ALTHOUGH THE FRONT MAY NOT FULLY CLEAR OUR SOUTHERN AREAS BY
WEDNESDAY AND THE HIGHEST POPS WILL BE SOUTHERN AND EASTERN AREAS.
DRIER CONDITIONS ARE EXPECTED FOR THURSDAY AND FRIDAY, BUT GIVEN
UNCERTAINTY ABOUT THE EXTENT OF THE DRYING IN THESE LONGER RANGES
THERE IS STILL A LOW CHANCE OF CONVECTION WITH PEAK HEATING
MAINLY SOUTH. HIGH TEMPERATURES THAT WILL RUN NEAR TO SLIGHTLY
ABOVE NORMAL FOR MUCH OF THE LONG TERM PERIOD WILL LIKELY BEGIN TO
EDGE UP SLIGHTLY BY FRIDAY.
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 90 / 30 50 20 60
KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 89 70 90 / 50 50 30 50
OAK RIDGE, TN 69 88 70 90 / 40 50 30 50
TRI CITIES AIRPORT, TN 66 86 68 88 / 40 50 40 60
MRX WATCHES/WARNINGS/ADVISORIES
NC...NONE.
TN...NONE.
VA...NONE.
SHORT TERM...
AVIATION...AC
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