321
FXUS63 KLMK 291912
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
312 PM EDT MON JUN 29 2026
KEY MESSAGES
* HOT AND HUMID TODAY WITH AFTERNOON HIGHS IN THE LOW TO MID 90S
AND PEAK AFTERNOON HEAT INDICES IN THE 100 TO 115 DEGREE
RANGE. AN EXTREME HEAT WARNING IS NOW IN EFFECT THROUGH
THURSDAY.
* A STRONG RIDGE OF HIGH PRESSURE OVER THE REGION WILL BRING THE
HOTTEST TEMPERATURES SO FAR THIS YEAR. THE HEAT WILL PEAK
TUESDAY THROUGH THURSDAY, WITH AFTERNOON HIGHS IN THE MID 90S
AND PEAK INDEX VALUES OF 100 TO 115F.
* HOT AND HUMID FOR THE FOURTH OF JULY HOLIDAY WEEKEND, WITH
ISOLATED TO SCATTERED STORMS POSSIBLE IN THE AFTERNOON AND
EVENING. LOCALIZED FLASH FLOODING AND/OR LOCALIZED GUSTY WINDS
WILL BE POSSIBLE EACH AFTERNOON AND EVENING WITH ANY SLOW MOVING
STORM.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 310 PM EDT MON JUN 29 2026
THE WELL-ADVERTISED ANOMALOUS UPPER RIDGE BUILDS IN AND CENTERS OVER
OUR REGION THROUGH TOMORROW. DRY FORECAST DURING THIS TIME WITH
STRONG SUBSIDENCE INVERSION SHOWING UP ON AREA FORECAST SOUNDINGS.
THE MAIN STORY WILL BE THE HEAT AND HUMIDITY WITH TEMPS EXPECTED IN
THE LOW AND MID 90S COMBINED WITH DEW POINTS IN THE 70S. AREAWIDE
MAX HEAT INDICES ARE EXPECTED TO RANGE IN THE 100 TO 115F RANGE EACH
AFTERNOON AND EVENING, WITH LITTLE RELIEF AT NIGHT AS TEMPERATURES
ONLY INTO THE MID AND UPPER 70S FOR MOST. GIVEN THE PROLONGED NATURE
OF THE HEAT AND HUMIDITY, A BUSY OUTDOOR WEEK LEADING UP TO THE
HOLIDAY, RECENT FLOOD IMPACTS AND RECOVERY ONGOING DECIDED TO
UPGRADE THE ENTIRE AREA TO AN EXTREME HEAT WARNING IN COORDINATION
WITH SURROUNDING OFFICES. DO THINK TEMPERATURES WILL STRUGGLE A BIT
WITH THE RECENT HEAVY RAINFALL, AND AVAILABLE LOW LEVEL MOISTURE
CONTRIBUTING TO SCT-BKN CU FIELDS EACH AFTERNOON/EVENING, HOWEVER
ANY DECREASE IN MAX TS WILL LIKELY BE OFFSET BY HIGHER DEW POINTS SO
IT MAY END UP BEING A WASH ON PEAK AFTERNOON HEAT INDICES. NOT MUCH
ELSE TO SPEAK ABOUT IN THE SHORT TERM OTHER THAN PERHAPS SOME PATCHY
FOG POSSIBLE TONIGHT.
LONG TERM /TUESDAY THROUGH MONDAY/
ISSUED AT 310 PM EDT MON JUN 29 2026
WEDNESDAY AFTERNOON - FRIDAY NIGHT...
ANOMALOUS UPPER RIDGE PERSISTS OVER THE REGION, ALTHOUGH THE CENTER
WILL SHIFT SLIGHTLY EAST TO THE CENTRAL APPALACHIANS. STILL ENOUGH
INFLUENCE TO KEEP US HOT, MUGGY, AND MOSTLY DRY. FORECAST SOUNDINGS
FOR THIS TIME DO SHOW A WEAKENED MID LEVEL CAP/SUBSIDENCE INVERSION,
HOWEVER WITHOUT ANY REAL TRIGGERING MECHANISM, NOT SURE WE'LL BE
ABLE TO TAP INTO THE STRONG UNSTABLE AIRMASS CHARACTERIZED BY 4000-
5000 J/KG OF CAPE, AT LEAST NOT THROUGH WEDNESDAY. THERE IS AN
ALTERNATE SCENARIO THAT COULD PLAY OUT, HOWEVER IT IS THE LESS
LIKELY OUTCOME AT THIS POINT. SEE MORE DETAILS IN THE "ALTERNATE
SCENARIO" SECTION BELOW.
OPPRESSIVE HEAT WILL CONTINUE TO BE THE STORY THROUGH MID TO LATE
WEEK. TEMPERATURES ARE EXPECTED TO REACH SOLIDLY INTO THE MID 90S
ALONG WITH DEW POINTS WELL INTO THE 70S EACH DAY. THIS SHOULD
CONTINUE TO YIELD MAX AFTERNOON HEAT INDICES MOSTLY IN THE 100 TO
110F RANGE THROUGH AT LEAST THURSDAY. AS WE GET INTO LATER THURSDAY
AND FRIDAY, THE UPPER RIDGE DOES CENTER MORE ON THE MID-ATLANTIC
WITH SLIGHTLY LESS INFLUENCE OVER OUR AREA. CHANCES FOR ISOLATED TO
WIDELY SCATTERED DIURNALLY DRIVEN THUNDERSTORMS WILL INCREASE BY
THIS TIME. FORECAST SOUNDINGS SHOW STRONG INSTABILITY WITH LITTLE TO
NO VERTICAL SHEAR, SO STORM MODES WOULD CERTAINLY BE PULSE IN
NATURE. GIVEN SLOW STORM MOVEMENT, AND POTENTIAL FOR INTENSE
RAINFALL RATES DUE TO THE AMOUNT INSTABILITY AND NOTABLY HIGH PWATS,
DO THINK WE COULD START RUNNING INTO SOME ISOLATED FLASH FLOOD
CONCERNS FOR AREAS THAT HAVE ALREADY BEEN HIT HARD. SOMETHING TO
WATCH IN THIS PATTERN. HOPEFULLY, GIVEN THE LACK OF A STRONG TRIGGER
OTHER THAN DIURNAL HEATING, COVERAGE WILL BE SPARSE IN NATURE. WE'LL
ALSO HAVE TO WATCH FOR SOME MARGINALLY SEVERE HAIL OR MICROBURST
WINDS WITH THE PULSE STORM MODES.
SATURDAY - MONDAY...
THE UPPER RIDGE STEADILY BREAKS DOWN THROUGH THE WEEKEND WITH A BELT
OF PROGRESSIVE ZONAL WESTERLIES STARTING TO GAIN INFLUENCE INTO OUR
REGION. FINE DETAILS ARE LOWER CONFIDENCE, HOWEVER THERE IS A
GENERAL CONSENSUS OF AT LEAST A SHORTWAVE OR TWO EMBEDDED WITHIN
THIS FLOW ACTING AS A TRIGGER FOR MORE SCATTERED TO NUMEROUS SHOWER
AND STORM COVERAGE. THE BEST SIGNAL IS FOR LATE WEEKEND INTO EARLY
NEXT WEEK (SUNDAY OR MONDAY) WHEN A MORE PRONOUNCED SHORTWAVE MAY
PROGRESS THROUGH THE REGION, ALONG WITH A SURFACE COLD FRONT. DON'T
LOVE THE LOOK OF THE MORE ACTIVE PATTERN THROUGH THE WEEKEND
FOLLOWED BY A FRONTAL BOUNDARY PASSAGE GIVEN CONTINUED SLOW STORM
MOVEMENT THANKS TO WEAK DEEP LAYER SHEAR. WE COULD END UP WITH
ANOTHER WEEKEND FILLED WITH DUAL THREAT STORMS CAPABLE OF LOCALIZED
SEVERE WINDS AND/OR LOCALIZED FLASH FLOODING. THE GOOD NEWS IS THAT
ANY TORNADO THREATS WILL NOT BE REALIZED IN THIS TYPE OF
ENVIRONMENT. THIS IS DEFINITELY MORE OF A MID TO LATE SUMMER TYPE OF
SETUP. ANOTHER PIECE OF GOOD NEWS IS THAT THIS SHOULD PROVIDE SOME
RELIEF FROM THE HEAT, HOWEVER WE WILL STILL LIKELY BE AT OR JUST
ABOVE NORMAL FOR TEMPS AHEAD OF THIS EXPECTED COOL FRONT.
"ALTERNATE SCENARIO"
THERE IS ONE SCENARIO THAT WE SHOULD KEEP IN THE BACK OF OUR MIND,
AND IT HAS BEEN SHOWN ON TWO CONSISTENT RUNS OF THE GFS. IN THIS
ENVIRONMENT, WE CAN BE CONDUCIVE TO "CHAIN REACTION" TYPE EVENTS
WHERE A SINGLE PULSE STORM CAN CAUSE AN EVENTUAL LARGE COMPLEX OF
STORMS GIVEN MULTIPLE GENERATION UPDRAFTS BEING TRIGGERED BY THE
PREVIOUS PULSE STORM COLLAPSING. THESE CAN BECOME QUITE CHAOTIC,
ESPECIALLY GIVEN THE AMOUNT OF AVAILABLE CAPE EXPECTED UNDER THE
UPPER RIDGE. ANY LARGE COMPLEX OF STORMS CAUSED BY THIS CHAIN
REACTION SCENARIO, OR AN UPSTREAM MCS COULD WRECK THE MID TO LATE
WEEK TEMP FORECAST, AND IT HAS HAPPENED BEFORE. IT LOOKS LOOKS LIKE
THE EARLIEST THIS COULD HAPPEN WOULD BE LATER WEDNESDAY, HOWEVER IT
WOULD BECOME INCREASINGLY POSSIBLE MORESO ON THURSDAY OR FRIDAY.
WE'LL AT LEAST HAVE 3 SOLID DAYS OF OPPRESSIVE HEAT/HUMIDITY BEFORE
THIS OCCURS, SO STILL FELT THE DURATION BASED EXTREME HEAT WARNING
IS WARRANTED REGARDLESS OF IF AN MCS COULD BUST TEMPS LATE WEEK.
AVIATION /18Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 130 PM EDT MON JUN 29 2026
HIGH PRESSURE AT THE SURFACE AND ALOFT WILL CONTROL THE REGION FOR
THIS TAF CYCLE, AND FOR THE UPCOMING WEEK. LOOK FOR SCT-BKN CUMULUS
CLOUDS BETWEEN 3500-4500 FT THIS AFTERNOON. LIGHT TO STEADY SSW WIND
BETWEEN 5 AND 10 MPH ARE EXPECTED DURING THE AFTERNOON, WITH LIGHT
WINDS OVERNIGHT. CAN'T RULE OUT SOME PATCHY FOG GIVEN THE AMOUNT OF
LOW LEVEL MOISTURE, HOWEVER UPPER SKY COVER AND SOME LIGHT WINDS
KEEPING THE LOW LEVELS MIXED MAY BE JUST ENOUGH TO MITIGATE THE FOG
POTENTIAL. WILL LEAVE IT OUT FOR NOW WITH LOW CONFIDENCE.
LMK WATCHES/WARNINGS/ADVISORIES
KY...EXTREME HEAT WARNING UNTIL 9 PM EDT /8 PM CDT/ THURSDAY FOR
KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...EXTREME HEAT WARNING UNTIL 9 PM EDT /8 PM CDT/ THURSDAY FOR
INZ076>079-083-084-089>092.
SHORT TERM...BJS
LONG TERM...BJS
AVIATION...BJS
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