435
FXUS63 KIND 081903
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
303 PM EDT TUE SEP 8 2026
KEY MESSAGES
- HEAT RETURNS TODAY AND WEDNESDAY WITH PEAK HEAT INDICES IN THE
UPPER 90S AND LOW 100S WEDNESDAY AFTERNOON
- STRONG THUNDERSTORMS POSSIBLE LATE WEDNESDAY; RAIN AND STORMS
CONTINUE WEDNESDAY NIGHT INTO THURSDAY WITH HEAVY RAIN AND LOCALIZED
FLOODING AS THE PRIMARY CONCERN
- COOLER WEATHER RETURNS LATE WEEK, WARMING UP DURING THE WEEKEND.
DISCUSSION (THIS EVENING THROUGH TUESDAY)
ISSUED AT 303 PM EDT TUE SEP 8 2026
UPPER-LEVEL RIDGING OVER THE PLAINS IS FLATTENING AND MOVING
EASTWARD AS A POTENT SHORTWAVE DIGS SOUTHWARD INTO THE DAKOTAS. THIS
HAS PUSHED THE RIDGE AXIS OVER INDIANA ALLOWING TEMPERATURES TO ONCE
AGAIN WARM UP. READINGS IN THE UPPER 80S TO LOW 90S ARE EXPECTED
TODAY AND WEDNESDAY. THE SHORTWAVE'S ATTENDANT COLD FRONT ARRIVES
LATE WEDNESDAY, SLOWING IN ITS FORWARD SPEED AND LIKELY STALLING
OVER SOUTHERN INDIANA. UPPER-LEVEL FLOW BECOMES PARALLEL TO THE
BOUNDARY ALLOWING FOR REPEATED ROUNDS OF PRECIPITATION WEDNESDAY
EVENING INTO THURSDAY. THE VORT MAX DEPARTS LATER ON THURSDAY WITH
BROAD RIDGING TAKING HOLD AGAIN OVER THE PLAINS AS WE HEAD INTO THE
WEEKEND.
WEDNESDAY
SOUTHWESTERLY FLOW INCREASES AHEAD OF THE APPROACHING FRONT LATE
WEDNESDAY MORNING INTO THE AFTERNOON. THIS WILL PROMOTE STRONG LOW-
LEVEL MOISTURE ADVECTION WITH DEW POINTS RISING INTO THE 70S.
COMBINED MODEST COLD AIR ADVECTION ALOFT / HEIGHT FALLS, STRONG
INSTABILITY IS EXPECTED BY LATE WEDNESDAY AFTERNOON. GUIDANCE SHOWS
BETWEEN 2000-3000 J/KG MLCAPE ACROSS SOUTHERN INDIANA DECREASING
WITH NORTHWARD EXTENT. SHEAR INCREASES AS WELL DUE TO THE
APPROACHING SHORTWAVE, EASTERLY AT AROUND 30KT. THE FRONT ITSELF
WILL PROVIDE THE FORCING NECESSARY FOR CONVECTION.
GIVEN A SHEAR VECTOR LARGELY PARALLEL TO THE FRONT, A LINEAR
CONVECTIVE MODE APPEARS LIKELY. MARGINAL TO POOR LAPSE RATES SHOULD
LIMIT SEVERE POTENTIAL. MID-LEVEL DRYNESS COULD LEAD TO A DOWNBURST
OR TWO, GIVEN ABOUT 1000 J/KG DCAPE. OUR PRIMARY HAZARD APPEARS TO
BE FLASH FLOODING, WITH STORMS POTENTIALLY TRAINING DUE TO THE SLOW-
MOVING FRONT AND BOUNDARY-PARELLEL FLOW. CONVECTION MAY CONTINUE
INTO THE NIGHT AS ADDITIONAL ROUNDS DEVELOP DUE TO EMBEDDED
DISTURBANCES ALOFT. THE BEST CHANCE FOR BOTH SEVERE AND HYDRO
THREATS IS OVER OUR SOUTHERN CWA WHERE THE FRONT IS MOST LIKELY TO
STALL.
A POTENTIAL FAILURE MODE FOR CONVECTION ON WEDNESDAY IS RELATED TO
CONVECTION UPSTREAM TONIGHT. SHOULD AN OUTFLOW BOUNDARY SURGE
SOUTHWARD OUT OF ILLINOIS TOMORROW MORNING, A LOW-LEVEL STABLE LAYER
AND CAP MAY REMAIN IN PLACE MOST OF THE DAY. THIS, AS SHOWN BY THE
12Z HRRR MAY SUBSTANTIALLY LIMIT CONVECTIVE DEVELOPMENT.
THURSDAY
GUIDANCE IS IN GOOD AGREEMENT SHOWING SHOWERS AND THUNDERSTORMS
PERSISTING INTO THE DAY THURSDAY, WITH A FEW DIFFERENCES. THESE
DIFFERENCES ARE MAINLY REGARDING THE NORTHERN EXTENT OF
PRECIPITATION CHANCES. GLOBAL MODELS SUCH AS THE ECMWF AND GFS TEND
TO BRING A SLUG OF HEAVIER PRECIP RIGHT THROUGH CENTRAL INDIANA,
WHERE FINER-SCALE MODELS LIKE THE RAP AND NAM ARE FURTHER SOUTH. FOR
NOW, WE WILL NUDGE THE FORECAST TOWARDS THE SOUTHERN SIDE OF
GUIDANCE AS THERE HAS BEEN AN OVERALL TREND IN THAT DIRECTION TODAY.
THIS ALL DEPENDS ON WHERE THE FRONT ENDS UP STALLING, HOWEVER, WHICH
MAY BE INFLUENCED BY WEDNESDAY'S CONVECTIVE EVOLUTION. NEEDLESS TO
SAY, THERE IS A BIT OF UNCERTAINTY IN TERMS OF PRECIPITATION
PLACEMENT ON THURSDAY.
FRIDAY ONWARD
COOLER WEATHER ARRIVES THURSDAY AND CONTINUES INTO FRIDAY BEFORE
RIDGING RETURNS ON SATURDAY. HIGHS NEAR 80 ARE EXPECTED TO END THE
WEEK WITH TEMPERATURES RISING BACK TOWARDS 90 OVER THE WEEKEND.
TEMPS IN THE MID 80S TO NEAR 90 THEN PERSIST INTO EARLY NEXT WEEK. A
WEAK FRONT MAY ARRIVE FROM THE NORTH ON SUNDAY BUT MODEL CONSENSUS
IS POOR. POPS WILL BE LIMITED TO CHANCE (40 PERCENT) SUNDAY AND
MONDAY. MOST LOCATIONS SHOULD REMAIN DRY THROUGH THE WEEKEND.
AVIATION (18Z TAF ISSUANCE)
ISSUED AT 139 PM EDT TUE SEP 8 2026
IMPACTS:
- GUSTY SW WINDS AROUND 20 KTS WEDNESDAY AFTERNOON.
- SHOWERS WITH SCATTERED TS POSSIBLE BY 18Z NORTH TERMINALS, MORE
LIKELY AFTER 22Z AT KIND.
DISCUSSION:
QUIET AVIATION WEATHER IS EXPECTED FOR THE REMAINDER OF TODAY INTO
TONIGHT AS S-SW LOW LEVEL WINDS REMAIN GENERALLY UNDER 10 KTS UNDER
SCT-BKN CIRRUS CLOUDS. AROUND SUNSET WINDS WILL DECREASE AND BECOME
LIGHT SOUTHERLY AHEAD OF WEAK LOW PRESSURE ALONG A SLOWLY MOVING
COLD FRONT TO THE N-NW OF CENTRAL INDIANA. SCATTERED CONVECTION IS
EXPECTED OVERNIGHT WELL NORTH OF THE AREA ACROSS IOWA INTO NORTHERN
IL. AHEAD OF THIS SAGGING COLD FRONT, SW WINDS WILL INCREASE BY
WEDNESDAY AFTERNOON WITH GUSTS AROUND 20 KTS EXPECTED AT ALL
TERMINALS EXCEPT KLAF WHERE A FEW SHOWERS AND INCREASING MID LEVEL
CLOUD COVER WILL ARRIVE BY EARLY AFTERNOON.
STILL A GOOD DEAL OF UNCERTAINTY WITH REGARDS TO THE AMOUNT OF
CONVECTION EXPECTED ACROSS CENTRAL INDIANA TOMORROW AFTERNOON AND
EVENING. THIS IS PRIMARILY DUE TO THE AMOUNT OF MID LEVEL CLOUD
COVER EXPECTED BY MID AFTERNOON, POSSIBLE SCATTERED SHOWERS AND
THE COMBINED NEGATIVE EFFECTS ON LOW LEVEL INSTABILITY. FOR NOW
HAVE ADDED PROB30 FOR TS AT KIND STARTING AFTER 18Z WITH SHRA/VCTS
AFTER 22Z, WHEN THE MAIN FRONTAL BOUNDARY APPROACH WILL OCCUR
ALONG WITH POSSIBLY SLIGHTLY HIGHER INSTABILITY AMOUNTS.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
AVIATION...CROSBIE
DISCUSSION...ECKHOFF
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