009
FXUS63 KIND 120226
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1026 PM EDT TUE AUG 11 2026
KEY MESSAGES
- THUNDERSTORMS WILL BE AROUND AT TIMES THROUGH THE NIGHT AND
INTO WEDNESDAY
- FLOOD WATCH THROUGH WEDNESDAY ACROSS MUCH OF CENTRAL INDIANA
- ADDITIONAL STORMS DAILY THROUGH THE REST OF THE WEEK, FLOODING
WILL BE THE MAIN THREAT
FORECAST UPDATE
ISSUED AT 1026 PM EDT TUE AUG 11 2026
ALTHOUGH THE LARGE OUTFLOW BOUNDARY FROM EARLIER SEVERE CONVECTION
HAS PUSHED SOUTH AND WEST OF CENTRAL INDIANA, ISOLATED THUNDERSTORMS
CONTINUE TO DEVELOP ALONG A DIFFERENT BOUNDARY FROM NEAR LAFAYETTE
TO MARTINSVILLE TO EAST OF SEYMOUR. THESE ARE TAPPING INTO SOME
ELEVATED INSTABILITY AND WILL BECOME BRIEFLY STRONG AT TIMES.
DURING THE NIGHT, UPPER IMPULSES WILL WORK WITH WARM ADVECTION TO
GENERATE ADDITIONAL CONVECTION ACROSS THE AREA. MLCAPE WILL INCREASE
THANKS TO THE ADVECTION, SO STRONG TO POTENTIALLY SEVERE STORMS
REMAIN A THREAT (AS SHEAR REMAINS DECENT). HOWEVER, UNCERTAINTY
REMAINS ON HOW MUCH COVERAGE THERE WILL BE AND ON WHERE THE MOST
COVERAGE WILL OCCUR. FOR NOW BELIEVE THE MOST COVERAGE WILL BE
ACROSS THE NORTHEAST HALF OF THE AREA, SO WENT HIGH CHANCE TO LOW
END LIKELY POPS THERE. WENT LOWER POPS ELSEWHERE.
WITH THE RAIN THAT FELL SO FAR TODAY, AND THE HIGH MOISTURE CONTENT
OF THE ATMOSPHERE, FLOODING REMAINS A CONCERN THROUGH THE NIGHT.
THIS IS ESPECIALLY TRUE ACROSS THE NORTHEAST WHERE THE HEAVIEST RAIN
FELL.
RAIN COOLED AIR WILL KEEP TEMPERATURES NEARLY STEADY THROUGH THE
NIGHT. IF CLOUDS THIN/CLEAR OUT FOR LONG ENOUGH, FOG MAY DEVELOP.
DISCUSSION (THIS EVENING THROUGH TUESDAY)
ISSUED AT 233 PM EDT TUE AUG 11 2026
SURFACE ANALYSIS THIS AFTERNOON CONTINUES TO SHOW A WEAK TROUGH OF
LOW PRESSURE STRETCHING FROM NORTHERN IL ACROSS NORTHERN INDIANA
INTO OH. THIS AREA REMAINS THE FOCUS FOR CONVECTIVE DEVELOPMENT.
GOES19 SHOWS A LARGE THUNDERSTORM CLUSTER OVER NORTHERN INDIANA,
PROGRESSING TO THE SOUTHEAST. THUNDERSTORMS WERE FOUND STRETCHING
FROM A LAF TO NOBLESVILLE-ANDERSON-MUNCIE AREAS, AND WAS SAGGING
SOUTHWARD. BEST INSTABILITY ACROSS AREA REMAINED SOUTHWEST OF THE
STORMS WHERE SPC CAPE SHOWED VALUES OVER 4500 J/KG. LATEST ACARS
SOUNDINGS SHOW DEEP CAPE AVAILABLE. ALOFT WATER VAPOR SHOWS A SHORT
WAVE WITHIN THE NW FLOW ALOFT OVER EASTERN IL TRIGGERING OUR
CONVECTIVE CLUSTER AS THE NW FLOW CONTINUE TO STREAM FROM MT AND WY
TO INDIANA.
THIS AFTERNOON AND TONIGHT...
CONVECTION ACROSS THE NORTHERN PARTS OF THE FORECAST AREA IS
EXPECTED TO CONTINUE FOR THE NEXT SEVERAL HOURS AS THE UPPER WAVE
CONTINUES TO PROGRESS EAST. THUNDERSTORMS WILL TRY TO SAG SOUTHWARD
SOMEWHAT, WHERE THE BETTER INSTABILITY WILL BE LOCATED. THUS WILL
CONTINUE TO KEEP HIGH POPS IN PLACE IN THIS ALONG AND SOUTH OF THE
STORMS THROUGH THE AFTERNOON INTO THE EVENING. ADDITIONAL TSRA DUE
TO DAYTIME HEATING WILL BE POSSIBLE ACROSS SOUTHWESTERN CENTRAL
INDIANA AND LOWER POPS WILL STILL BE NEEDED THERE.
HRRR SHOWS THIS WAVE EXITING BY EARLY EVENING, AND A WORKED OVER
ATMOSPHERE SHOULD ALLOW STORMS TO END LEADING TO A MAINLY DRY
EVENING AND OVERNIGHT PERIOD. SOME FOG WILL BE POSSIBLE NEAR LAF DUE
TO THE HIGH DEW POINTS REMAINING ACROSS THE AREA ALONG WITH THE
LINGERING SURFACE BOUNDARY. LOOK FOR OVERNIGHT LOWS IN THE LOWER
70S AND THE HIGHEST POPS DURING THE EVENING HOURS.
WEDNESDAY...
THE PERSISTENT NW FLOW ALOFT IS EXPECTED TO REMAIN IN PLACE ON
WEDNESDAY, PERHAPS BECOMING A BIT MORE NORTHWESTERLY AS YET ANOTHER
SHORT WAVE IS EXPECTED TO PASS ACROSS CENTRAL INDIANA WITHIN THE
FLOW. AGAIN THE VERY WARM AND HUMID AIR MASS WILL BE IN PLACE
ALLOWING FOR PLENTY OF MOISTURE AND PWATS ONCE AGAIN ARE NEAR VALUES
1.81 INCHES. AGAIN AMPLE CAPE WILL BE IN PLAY ALSO. THUS HIGH POPS
WILL ONCE AGAIN BE USED ON WEDNESDAY AS THIS WAVE WILL PASS, MAINLY
IN THE AFTERNOON. WITH A GOOD AMOUNT OF DAYTIME HEATING AVAILABLE
THROUGH THE MORNING HOURS, HIGH TEMPERATURES SHOULD AGAIN REACH THE
UPPER 80S TO AROUND 90.
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT...
THROUGH THIS TIME PERIOD THERE IS VERY LITTLE CHANGE IN THE OVERALL
WEATHER PATTERN. THE SAME NW FLOW ALOFT IS EXPECTED TO BE IN PLACE
WITH SEVERAL EMBEDDED WAVES WITHIN THAT FLOW POISED TO PASS DURING
THIS TIME PERIOD. THE VERY WARM, HUMID AND UNSTABLE AIRMASS WILL
ALSO REMAIN. ALL OF THIS WILL ADD UP TO CONTINUED CHANCES FOR
SHOWERS AND THUNDERSTORMS, MAINLY CAPABLE OF PRODUCING VERY HEAVY
RAIN AND DAMAGING WINGS THROUGH THE PERIOD. CONTINUED POPS WILL BE
USED THROUGH THE PERIOD.
FRIDAY THROUGH SUNDAY NIGHT....
MORE HOT AND HUMID WEATHER IS EXPECTED THROUGH THE WEEKEND ALONG
WITH DAILY CHANCES FOR SHOWERS AND THUNDERSTORMS. MODELS SUGGEST
RIDGING ALOFT OVER THE PLAINS WILL BE BUILDING ACROSS CENTRAL
INDIANA THROUGH THE WEEKEND. A FEW RIDGE RIDING WAVES WITHIN A RING
OF FIRE TYPE PATTERN WILL BE CAPABLE OF PRODUCING OCCASIONAL SHOWERS
AND STORMS. FURTHER SUPPORT WILL COME FROM THE LOWER LEVELS. HERE, A
FRONTAL BOUNDARY WILL BE LINGERING ACROSS CENTRAL INDIANA ON FRIDAY
BEFORE PUSHING NORTH AS A WARM FRONT ON SATURDAY AHEAD OF LOW
PRESSURE OVER THE PLAINS. THE LOW WILL PUSH EAST OF INDIANA ON
SUNDAY, LIKELY DRAGGING A COLD FRONT ACROSS CENTRAL INDIANA.
FORECAST SOUNDINGS THROUGH SUNDAY SHOW PLENTIFUL MOISTURE AVAILABLE
THROUGH THE COLUMN. ALL OF THIS WILL AGAIN NECESSITATE POPS THROUGH
THE WEEKEND. THE WARM AIR MASS WILL RESULT IN HIGH TEMPERATURES IN
THE UPPER 80S TO AROUND 90.
MONDAY AND TUESDAY...
IN THE WAKE OF THE FRONT ON MONDAY, DRY AIR AND SUBSIDENCE IS SHOWN
TO ARRIVE AS HIGH PRESSURE FROM THE GREAT LAKES BUILDS ACROSS
CENTRAL INDIANA. FORECAST SOUNDINGS SHOW A DRY COLUMN AND FOR THE
FIRST TIME IN WHAT SEEMS LIKE A LONG TIME SHOW ZERO CAPE. ALOFT,
RIDGING IS EXPECTED TO RETURN OVER THE ROCKIES RESULTING IN NW FLOW
STREAMING ACROSS THE PLAINS INTO INDIANA. AT THE MOMENT IT APPEARS
THAT LITTLE TO NO FORCING WILL BE AVAILABLE, THIS WE SHOULD ABLE TO
USE A DRY FORECAST AT THAT TIME GIVEN THE THE EXPECTED SURFACE HIGH
PRESSURE.
AVIATION (00Z TAF ISSUANCE)
ISSUED AT 728 PM EDT TUE AUG 11 2026
IMPACTS:
- UNCERTAINTY ON STORM TIMING THROUGH TOMORROW; PERIODIC STORMS
EXPECTED
- LOW CONFIDENCE THREAT OF FOG FOR LAF AND HUF LATE TONIGHT
DISCUSSION:
ORGANIZED THUNDERSTORM COMPLEX IS SOUTH OF TAF SITES AS OF THIS
WRITING, WITH STRATIFORM TRAILING RAIN FOR A FEW MORE HOURS.
CONCERNS ARE FOR REDEVELOPMENT OF THUNDERSTORMS IN ILLINOIS WITHIN
WARM ADVECTION REGIME ATOP RESIDUAL OUTFLOW TONIGHT, AND THIS IS
PARTICULARLY DIFFICULT TO TIME. WE HAVE ATTEMPTED TO HIGHLIGHT MOST
LIKELY WINDOW FOR THUNDERSTORMS BUT THIS WILL LIKELY NEED TO BE
REFINED THROUGH AMENDMENTS AS TRENDS CONTINUE TO BE MONITORED.
DEPENDING ON THUNDERSTORMS AND RESIDUAL CLOUDS, THERE REMAINS A
CONDITIONAL SETUP FOR FOG AT/NEAR LAF AND HUF, THOUGH CONFIDENCE IS
LOWER THAN PREVIOUS FORECASTS.
DEPENDING ON THE EXPANSIVENESS OF STORMS LATER TONIGHT AND TOMORROW
MORNING, AFTERNOON REDEVELOPMENT IS LIKELY. AGAIN, TIMING AND
COVERAGE IS IN QUESTION SO WE HAVE A BROADER PROB30 FOR NOW. EXPECT
ADJUSTMENTS TO TIMING AND WE CANNOT COMPLETELY RULE OUT STORMS AT
ANY TAF SITES AT ANY TIME DURING THE 30 HOUR FORECAST PERIOD.
IND WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH WEDNESDAY EVENING FOR INZ021-028>031-035>049-
054>057-063>065-072.
UPDATE...50
AVIATION...BRB
DISCUSSION...PUMA
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