343
FXUS63 KLMK 050207
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1007 PM EDT FRI SEP 4 2026
KEY MESSAGES
* HEAT ADVISORY CONTINUES THROUGH SATURDAY AFTERNOON.
* TEMPERATURES FOR REMAINDER OF TODAY IN THE MID TO UPPER 90S WITH
HEAT INDEX VALUES OVER 100 AND UP TO 107. SATURDAY WILL AGAIN BE
HOT, WITH AFTERNOON HIGHS JUST A COUPLE OF DEGREES LOWER THAN
TODAY.
* WARM OVERNIGHT TEMPS TONIGHT IN THE MID TO UPPER 70S WILL PROVIDE
LITTLE RELIEF DURING THE NIGHTTIME HOURS. PRACTICE HEAT SAFETY BY
REMAINING HYDRATED AND LIMIT TIME OUTDOORS IF POSSIBLE.
* A WEAK COLD FRONT WILL INCREASE THE CHANCE OF ISOLATED TO
SCATTERED SHOWERS AND STORMS SATURDAY AFTERNOON AND EVENING,
ENDING OUR STRETCH OF HOT CONDITIONS ACROSS THE REGION BY THE END
OF THE WEEKEND.
UPDATE
ISSUED AT 1006 PM EDT FRI SEP 4 2026
AT THIS HOUR, MOSTLY CLEAR SKIES ARE OBSERVED ON NIGHTTIME
MICROPHYSICS SATELLITE IMAGERY, WITH A COUPLE AREAS OF LINGERING CU
AND HIGH THIN CLOUDS NOTED. TEMPERATURES ARE GENERALLY IN THE 80S AT
02Z, THOUGH A FEW RURAL SITES HAVE ALREADY DROPPED INTO THE UPPER
70S. FOR THE REST OF THIS EVENING AND MOST OF THE OVERNIGHT,
PRECIPITATION CHANCES ARE VERY LOW (<10%), AS THE MID- AND UPPER-
LEVEL RIDGE SIT OVER THE TN VALLEY. IN AREAS WHICH RECEIVED
SUBSTANTIAL (>0.25") RAINFALL THIS AFTERNOON, SOME PATCHY FOG WILL
BE POSSIBLE SATURDAY MORNING; HOWEVER, GIVEN THE SPATIAL EXTENT
SHOULD BE VERY ISOLATED, NOT PLANNING TO ADD THIS TO THE GRIDS AT
THIS TIME.
OVER THE NEXT 12-18 HOURS, WE'LL HAVE TO WATCH NASCENT CONVECTION
OVER THE LOWER GREAT LAKES WHICH IS EXPECTED TO DROP TO THE
SOUTHEAST AND STRENGTHEN IN THE PRESENCE OF AMPLE MLCAPE (3000+
J/KG). WHILE THE ENVIRONMENT OVER OUR AREA IS NOT NEARLY AS
FAVORABLE, SOME OF THIS CONVECTION MAY BE ABLE TO MAKE IT INTO OUR
NORTHERN AND NORTHEASTERN ZONES BY THE MID-MORNING HOURS. TO ACCOUNT
FOR SOLUTIONS LIKE THE 0Z HRRR WHICH FEATURE THIS WAVE OF SHOWERS
AND STORMS, HAVE ADDED A CHANCE POP ALONG AND NORTHEAST OF A SALEM,
IN TO STANFORD, KY LINE. HOWEVER FAR SOUTHWEST THIS MORNING
CONVECTION MAKES IT WILL HAVE RAMIFICATIONS FOR TEMPERATURES AND
PRECIPITATION CHANCES LATER IN THE DAY ON SATURDAY, AS NEW SHOWERS
AND STORMS WILL LIKELY DEVELOP PREFERENTIALLY ALONG THE RESIDUAL
OUTFLOW FROM MORNING CONVECTION.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 356 PM EDT FRI SEP 4 2026
THE HOTTEST STRETCH OF THE YEAR ACROSS THE REGION CONTINUES THIS
AFTERNOON AS BROAD UPPER-LEVEL RIDGING REMAINS SITUATED OVER THE
CENTRAL AND PARTS OF THE EASTERN CONUS. LOUISVILLE (SDF) RECENTLY
HIT 100 DEGREES FOR THE FIRST TIME SINCE AUGUST 30, 2024, AND THE
FIRST SEPTEMBER INSTANCE SINCE SEPTEMBER 3, 2011. IN ADDITION TO THE
HEAT, ISOLATED TO WIDELY SCATTERED SHOWERS AND STORMS HAVE DEVELOPED
THIS AFTERNOON, MAINLY FOR PLACES SOUTH OF I-64. THE WEAK WIND SHEAR
IN PLACE WILL LIMIT THE ABILITY FOR MORE WIDESPREAD DEVELOPMENT AND
STRONGER STORMS. THE STRONGEST STORMS COULD PRODUCE GUSTIER WINDS,
BUT THE LIKELIHOOD FOR ANY SEVERE STORMS TO DEVELOP REMAINS VERY
LOW.
ANY SHOWERS AND STORMS THAT DO DEVELOP THIS AFTERNOON WILL QUICKLY
DISSIPATE AFTER SUNSET, RESULTING IN WHAT SHOULD BE A DRY OVERNIGHT
ACROSS THE REGION. A FEW CLUSTERS OF SHOWERS AND STORMS ARE LIKELY
TO MOVE OVER CENTRAL INDIANA AND OHIO TONIGHT, BUT SHOULD REMAIN OFF
TO OUR NORTH AS THEY MOVE THROUGH. SINCE AN ISOLATED SHOWER CANNOT
BE COMPLETELY RULED OUT, SLIGHT CHANCE (<20%) POPS WERE INCLUDED IN
THE NORTHERN PORTIONS OF THE AREA. WITH THE UPPER RIDGE STILL IN
PLACE, OVERNIGHT TEMPERATURES WILL REMAIN WARM, ONLY DROPPING DOWN
TO THE MID 70S.
FOR SATURDAY, A SURFACE "COLD" FRONT WILL MOVE SOUTHWARD THROUGH THE
REGION, BRINGING A MUCH-NEEDED END TO THIS HEAT WAVE. THE FRONT
WON'T EXIT TO OUR SOUTH UNTIL SATURDAY NIGHT, WHICH WILL ALLOW FOR
TEMPERATURES IN THE MID TO UPPER 90S IN THE AFTERNOON. THE AREA-WIDE
HEAT ADVISORY REMAINS IN EFFECT UNTIL SATURDAY EVENING, WITH
EXPECTED HEAT INDICES OF 100-107.
THE FRONTAL BOUNDARY WILL ALSO ACT AS A FORCING MECHANISM FOR MORE
WIDESPREAD SHOWERS AND STORMS TO DEVELOP TOMORROW AFTERNOON. WHILE
ELEVATED MOISTURE (PW ~1.7") AND INSTABILITY (1500-2000 J/KG
SBCAPE), WEAKER WIND SHEAR (15-25 KT 0-6 KM SHEAR) WILL BE A
LIMITING FACTOR TO THE INTENSITY OF THESE SHOWERS AND STORMS. THE
SPC HAS PLACED THE BLUEGRASS UNDER A SLIGHT RISK FOR SEVERE WEATHER
SATURDAY, WITH DAMAGING WINDS AND VERY ISOLATED HAIL BEING THE
PRIMARY CONCERNS. CHANCES FOR SHOWERS AND STORMS QUICKLY DECREASE
SATURDAY NIGHT AS THE FRONT PUSHES SOUTHWARD AND WE LOSE DAYTIME
HEATING. WHILE OVERNIGHT TEMPERATURES WON'T BE AS WARM, THEY WILL
STILL BE MILD WITH LOWS IN THE UPPER 60S TO LOW 70S.
LONG TERM /SUNDAY THROUGH FRIDAY/
ISSUED AT 356 PM EDT FRI SEP 4 2026
ONCE THE "COLD" FRONT DEPARTS OUT OF THE REGION, SURFACE HIGH
PRESSURE AND DRIER AIR FILLS IN. THIS WILL ALSO MARK THE START OF
OUR MUCH NEEDED REPRIEVE FROM THE PROLONGED HEAT WAVE, WITH
WIDESPREAD AFTERNOON HIGHS IN THE MID TO UPPER 80S AND ISOLATED LOW
90S FORECAST THROUGH THE EARLY PARTS OF NEXT WEEK. OVERNIGHT LOWS
WILL ALSO BE QUITE COMFORTABLE SUNDAY AND MONDAY NIGHT, WITH
TEMPERATURES IN THE 90S EXPECTED. IN ADDITION, THIS WILL ALSO START
A STRETCH OF MOSTLY DRY CONDITIONS THAT IS EXPECTED TO LAST THROUGH
MIDWEEK. WHEN LOOKING BROADLY AT THE UPPER-LEVEL PATTERN, THE WELL
AMPLIFIED UPPER RIDGE OVER THE CENTRAL CONUS WILL BEGIN TO SLOWLY
BREAK DOWN BEGINNING LATE MONDAY AND SHIFT EASTWARD TOWARDS THE
MIDWEST AND OHIO VALLEY. THIS WILL HELP SHIFT THE LOWER-EVEL FLOW
BACK SOUTHWARD AND ALLOW WARMER AIR TO RETURN, WITH HIGHS IN THE LOW
TO MID 90S FORECAST TUESDAY-WEDNESDAY.
FOR THE LATTER PORTIONS OF THE FORECAST PERIOD (LATE WEDNESDAY AND
BEYOND), A MORE NOTICEABLE PATTERN SHIFT COULD BE IN STORE FORE THE
OHIO VALLEY. GUIDANCE IS PICKING UP ON A ROBUST UPPER LEVEL LOW
TREKKING TOWARDS THE NE CONUS AND QUEBEC BY LATE WEEK. AS IT DOES
SO, A SOUTHWARD EXTENDING COLD FRONT WILL PASS THROUGH OUR REGION,
PROVIDING THE NEXT OPPORTUNITY FOR MORE WIDESPREAD PRECIPITATION.
THE TIMING AND PROGRESSION OF THIS SYSTEM VARIES GREATLY ACROSS THE
DETERMINISTIC AND ENSEMBLE GUIDANCE,RESULTING IN A WIDE VARIETY OF
SOLUTIONS. FOR EXAMPLE, WHEN LOOKING AT THE LREF MAXIMUM
TEMPERATURES FOR THURSDAY-SATURDAY THE 25-75TH PERCENTILE SPREAD IS
QUITE CONSIDERABLE (10-15 DEGREE SPREAD EACH DAY), RANGING FROM THE
LOW 80S TO UPPER 90S. AS A RESULT, OUR CONFIDENCE IN ANY PARTICULAR
OUTCOME IS VERY LOW, BUT WILL BE SOMETHING TO MONITOR AS TIME
PROGRESSES.
AVIATION /00Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 747 PM EDT FRI SEP 4 2026
VFR CONDITIONS ARE LIKELY THROUGH THE CURRENT FORECAST PERIOD, WITH
A FEW LOW CONFIDENCE SCENARIOS THAT COULD IMPACT OPERATIONS. THIS
EVENING, MOST OF THE SHOWERS AND STORMS HAVE DISSIPATED, WITH DRY
CONDITIONS LIKELY THROUGH SATURDAY AFTERNOON. ONE OUTLIER SCENARIO
(10-20% PROBABILITY) FEATURES A GUSTY LINE OF SHOWERS SURGING FROM
THE NE EARLY TOMORROW MORNING, MAINLY BETWEEN 10-14Z. MORE THAN
LIKELY, THIS COMPLEX WILL REMAIN AWAY FROM FORECAST SITES, BUT IT'S
SOMETHING TO LOOK OUT FOR.
OTHERWISE, TONIGHT SHOULD FEATURE LIGHT AND VARIABLE WINDS, WITH
WINDS INCREASING OUT OF THE W/NW DURING THE MID-TO-LATE MORNING
HOURS SATURDAY. A FEW 15-20 KT GUSTS WILL BE POSSIBLE AT SDF AND LEX
TOMORROW AFTERNOON, WITH WINDS VEERING TOWARD THE NORTH BY THE END
OF THE FORECAST PERIOD. ANOTHER MID-LEVEL CU DECK SHOULD DEVELOP,
WITH A BETTER CHANCE OF SHOWERS AND STORMS EXPECTED TOMORROW
AFTERNOON AS A COLD FRONT MOVES IN FROM THE NORTH. MAY NEED TO ADD
MORE PROB30/TEMPO MENTIONS FOR STORMS IF CONFIDENCE INCREASES, WITH
THE MAIN WINDOW FOR STORMS BEING 20-02Z SATURDAY AFTERNOON/EVENING.
LMK WATCHES/WARNINGS/ADVISORIES
KY...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ SATURDAY FOR
KYZ023>043-045>049-053>057-061>067-070>078-081-082.
IN...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ SATURDAY FOR
INZ076>079-083-084-089>092.
UPDATE...CSG
SHORT TERM...BEN
LONG TERM...BEN
AVIATION...CSG
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page