675
FXUS63 KLMK 121309
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
909 AM EDT WED AUG 12 2026
..FORECAST UPDATE
KEY MESSAGES
* WAVES OF THUNDERSTORMS INTO TONIGHT COULD GENERATE SEVERE WEATHER,
WITH DAMAGING WINDS THE PRIMARY HAZARD AND A LOWER RISK FOR LARGE
HAIL. THE RISK APPEARS GREATEST (15-29%) NEAR AND WEST OF I-65
DURING THE EVENING.
* REPEATED ROUNDS OF HEAVY RAINFALL IN THUNDERSTORMS THROUGH THIS
EVENING COULD RESULT IN FLASH FLOODING. THERE IS A LEVEL 2 OF 4
(SLIGHT) RISK FOR EXCESSIVE RAINFALL AREA-WIDE.
* ADDITIONAL ROUNDS OF STORMS ARE POSSIBLE (40-60% CHANCE) BOTH
TOMORROW AND FRIDAY, BUT CONFIDENCE IS LOW ON SEVERE WEATHER AND
FLOODING POTENTIAL EACH DAY.
* OUTSIDE OF STORMS, HEAT INDICES ARE LIKELY (50-80% CHANCE) TO
SURPASS 100 DEGREES WEST OF I-65 EACH AFTERNOON THROUGH THURSDAY,
AND AREA-WIDE OVER THE WEEKEND.
UPDATE
ISSUED AT 907 AM EDT WED AUG 12 2026
WENT AHEAD AND EXPANDED THE FLOOD WATCH ALONG AND NORTH OF I-64.
CURRENT N-S ORIENTED CONVECTION CONTINUES TO BE FED BY A WEAK BUT
PERSISTENT LOW LEVEL JET. THIS FEATURE IS EXPECTED TO WEAKEN THROUGH
THE MORNING, AND THE OVERALL CONVECTIVE INTENSITY HAS BEEN TRENDING
SLOWLY DOWNWARD. STILL, TRAINING OF MODERATE TO BRIEFLY HEAVY
SHOWERS AND STORMS WILL CONTINUE FOR A WHILE THIS MORNING, BEFORE AT
LEAST SOME BRIEF LULL IN CONVECTION MAY OCCUR.
FOCUS THEN SHIFTS UPSTREAM FOR AN AFTERNOON/EVENING ROUNDS OF STORMS
APPROACHING FROM THE NW. THIS LINE OF STRONG TO SEVERE STORMS
COMBINED WITH ANOTHER ROUND OF TRAINING CONVECTION POSSIBLE ON THE
REMNANT OUTFLOW BOUNDARY OVERNIGHT WAS ENOUGH TO JUSTIFY EXPANDING
AND EXTENDING THE FLOOD WATCH THROUGH 12Z. THERE ARE SOME CONCERNS
IN THE 12/00Z HREF DATA FOR SW INDIANA WHERE LOCALIZED RAINFALL
AMOUNTS OVER 5" ARE SHOWING UP IN MAX ENSEMBLE MEMBERS AND BACKED UP
BY THE PMM DATA.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 309 AM EDT WED AUG 12 2026
***** FLOODING POTENTIAL THROUGH THIS EVENING *****
AT 3 AM EDT, HEAVY THUNDERSTORMS WERE LOCATED OVER SOUTHEAST AND
EAST-CENTRAL INDIANA, HAVING FORMED AT THE INTERFACE OF A 30-35 KT
LLJ AND A LEFTOVER BOUNDARY FROM EVENING STORMS. THESE SHOULD
CONTINUE TO DRIFT SOUTHEAST INTO SOUTHWEST OHIO AND NORTHEAST
KENTUCKY WHILE ADDITIONAL ACTIVITY BACKBUILDS TO THE NORTH AND
NORTHWEST OVER CENTRAL/NORTHERN INDIANA. THIS SUGGESTS THAT THE FOCUS
FOR HEAVY RAINFALL AND FLASH FLOODING POTENTIAL WILL BE RIGHT ALONG
THE NORTHEAST EDGE AND JUST OUTSIDE OF OUR LOCAL AREA. HOWEVER, A
FEW OF THE 00Z CAMS SUGGEST ADDITIONAL BACKBUILDING TOWARDS THE WEST
COULD BRING REPEATED ROUNDS OF HEAVY THUNDERSTORMS INTO OUR EASTERN
COUNTY WARNING AREA (CWA) DURING THE MID MORNING/AFTERNOON. IN FACT,
THE 00Z HREF LPMM HAS POCKETS OF OVER 3 INCHES OF RAINFALL ALONG AND
EAST OF ROUGHLY THE I-75 CORRIDOR BY 18Z/2PM; FOR THIS REASON, AND
BECAUSE HEAVY RAINFALL FROM LAST EVENING IN PARTS OF SOUTH-
CENTRAL/SOUTHEAST KENTUCKY HAS LOWERED THE FLASH FLOODING THRESHOLD
(FFG) TO LESS THAN 1.5 INCHES IN 6 HOURS IN SPOTS, WE'VE EXPANDED
THE FLOOD WATCH WESTWARD TO INCLUDE ANOTHER ROW OF COUNTIES. WHILE
THE WORST OF THIS MORNING WAVE COULD STAY OFF TO THE NORTH AND EAST,
THE CAMS SEEM TO AGREE THAT THE NEXT MID-LEVEL SHORTWAVE ARRIVING
DURING THE EVENING WILL SPARK ADDITIONAL STORMS THAT COULD PROVE
EFFICIENT RAINMAKERS (>1 IN/HOUR RATES).
***** SEVERE WEATHER RISK THIS EVENING *****
THE CAMS SEEM TO BROADLY AGREE THAT, ONCE AGAIN, A COMPLEX OF SEVERE
THUNDERSTORMS WILL DEVELOP OVER EASTERN IOWA/NORTHERN ILLINOIS LATER
THIS MORNING. THEIR SOLUTIONS DIVERGE, HOWEVER, IN WHAT HAPPENS ONCE
THAT COMPLEX REACHES INDIANA. THE LATEST (04Z) HRRR, FOR EXAMPLE,
HAS THE LINE RACING EASTWARD ACROSS NORTHERN INDIANA AND NORTHERN
OHIO, WHILE THE NAMNEST AND ARW, BY CONTRAST, SUGGEST IT WILL TAKE A
DIVE SOUTHWARD OVER EAST-CENTRAL ILLINOIS AND SOUTHERN INDIANA
DURING THE AFTERNOON. HOWEVER, EVEN THE HRRR SUGGESTS THE MCS WILL
LAY OUT AN OUTFLOW BOUNDARY ON WHICH ADDITIONAL CONVECTION WILL FIRE
DURING THE LATE AFTERNOON OVER CENTRAL/SOUTHERN INDIANA, WITH THAT
ACTIVITY TRACKING SOUTHEAST INTO OUR AREA DURING THE EVENING HOURS.
THE MAIN DIFFERENCE BETWEEN THE TWO SOLUTIONS IS TIMING, WITH THE
ARW AND NAMNEST BEING A LITTLE FASTER (LATE AFTERNOON/EARLY EVENING
VS LATE EVENING). IF THIS EARLIER OUTCOME MATERIALIZES, HIGHER
DIURNAL INSTABILITY WOULD SUGGEST A GREATER SEVERE WIND RISK, WHILE
THE SLOWER HRRR OUTCOME WOULD MEAN THE RISK WILL BE LOWER, AT LEAST
FOR AREAS EAST OF I-65. LIKE YESTERDAY, HODOGRAPHS EXHIBIT MODEST
CLOCKWISE CURVATURE IN THE LOWEST KILOMETER OF THE ATMOSPHERE, WHICH
MAY MAINTAIN A BIT OF A MESSY STORM MODE, WITH BROKEN LINEAR
SEGMENTS COMPRISED OF INDIVIDUAL CELLS WHICH COULD AT TIMES EXHIBIT
DEVIANT MOTION TOWARDS THE RIGHT; IN ADDITION, THE RESULTANT 100-200
M^2/S^2 0-1KM SRH COULD FAVOR A BRIEF TORNADO WITH ANY INDIVIDUAL
CELLS, PARTICULARLY RIGHT MOVERS THAT REALIZE THE BEST LOW LEVEL
SHEAR. THESE WILL ALSO BE THE ONES TO WATCH FOR LOCALLY SEVERE HAIL,
WHICH, DESPITE THE WARM AND HUMID ENVIRONMENT, WAS OBSERVED IN OUR
AREA YESTERDAY IN THE MOST ROBUST UPDRAFTS. SPC HAS THE AREA
OUTLOOKED IN A LEVEL 2 OF 5 (SLIGHT) RISK FOR SEVERE WEATHER, WITH
DAMAGING WINDS THE PRIMARY RISK BUT A LOWER CHANCE FOR HAIL AND
TORNADOES.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 309 AM EDT WED AUG 12 2026
***** STORM CHANCES WANE, HEAT BUILDS INTO THE WEEKEND *****
GLOBAL MODELS AND THEIR ENSEMBLES AGREE THAT RIDGING WILL SLOWLY
BUILD OVER THE AREA INTO THE WEEKEND. ONE OR MORE ADDITIONAL MID-
LEVEL DISTURBANCES WILL OFFER THUNDERSTORM CHANCES THURSDAY INTO
FRIDAY, MAINLY EAST OF I-65, BUT THEN THE MCS CORRIDOR SHOULD SHIFT
TO THE NORTHEAST BY SATURDAY. THIS WILL ALLOW THE HEAT TO INTENSIFY
ACROSS THE AREA OVER THE WEEKEND, WITH TRIPLE DIGIT HEAT INDICES,
CONFINED TO AREAS MAINLY WEST OF I-65 TODAY AND TOMORROW, EXPANDING
EAST TO ENCOMPASS THE ENTIRE AREA BOTH SATURDAY AND SUNDAY. IN FACT,
THERE IS A 60-90% (20-40%) CHANCE HEATRISK REACHES THE MAJOR
(EXTREME) CATEGORY BY SUNDAY AFTERNOON - SUGGESTING AN INCREASED RISK
FOR HEAT-RELATED ILLNESS, ESPECIALLY AMONG VULNERABLE POPULATIONS
INCLUDING THOSE WITHOUT PROPER COOLING.
A SHORTWAVE TROUGH SHOULD FLATTEN THE RIDGE AND DROP A FRONTAL
BOUNDARY OVER THE AREA SOMETIME EARLY NEXT WORK WEEK, POTENTIALLY
OFFERING SOME RELIEF FROM THE HEAT FOR AT LEAST A PORTION OF THE
AREA AND SERVING AS A TRIGGER FOR SHOWERS AND STORMS. IT'S TOO EARLY
TO TELL WHETHER A SEVERE WEATHER RISK MAY MATERIALIZE WITH THIS
ACTIVITY, BUT THE JOINT PROBABILITY OF > 25 KT 0-6KM BULK SHEAR AND
> 2000 J/KG MUCAPE FROM THE LREF IS LESS THAN 20%, WHICH, AT LEAST
AT THIS POINT IN TIME, SUGGESTS THE RISK SHOULD BE RELATIVELY LOW.
GIVEN THE RICHLY MOIST AND UNSTABLE AIRMASS AHEAD OF THE TROUGH AND
ATTENDANT FRONT, HEAVY RAIN AND LOCALIZED MICROBURSTS IN WATER-LADEN
COLLAPSING CORES WOULD SEEM TO BE THE PRIMARY HAZARDS (IF ANY).
AVIATION /12Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 719 AM EDT WED AUG 12 2026
A COMPLEX OF THUNDERSTORMS CONTINUES TO PROGRESS SOUTHWARD ACROSS
AREAS MAINLY NEAR AND EAST OF THE I-65 CORRIDOR, RESULTING IN
TRANSIENT VISIBILITY AND CEILING DROPS INTO THE MVFR CATEGORY. THESE
STORMS SHOULD TEND TO WEAKEN AND BREAK UP LATER THIS MORNING, WITH
VFR CONDITIONS PREDOMINANT UNTIL THE NEXT WAVE OF STORMS DEVELOPS
DURING THE EVENING. WINDS ARE SHIFTING TO A TRANSIENT NORTHEASTERLY
DIRECTION WITH THESE STORMS, BUT SHOULD BE PREDOMINANTLY OUT OF THE
SOUTHWEST THROUGHOUT THE FORECAST PERIOD.
LMK WATCHES/WARNINGS/ADVISORIES
KY...FLOOD WATCH THROUGH THURSDAY MORNING FOR KYZ025-029>043-
047>049-055>057-066-067.
IN...FLOOD WATCH THROUGH THURSDAY MORNING FOR INZ076>079-083-084-
089>092.
UPDATE...BJS
SHORT TERM...JRB
LONG TERM...JRB
AVIATION...JRB
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page