309
FXUS63 KIND 201632
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
1232 PM EDT SUN SEP 20 2026
KEY MESSAGES
- SCATTERED TO NUMEROUS SHOWERS AND STORMS WILL BE AROUND AT TIMES
LATER TODAY AND TONIGHT.
- AN ISOLATED SEVERE STORM WITH DAMAGING WINDS IS POSSIBLE THIS
AFTERNOON. LOCALLY HEAVY RAIN REMAINS A THREAT.
- RAIN CHANCES CONTINUE EARLY THIS WEEK, THEN DRY WEATHER SHOULD
RETURN. TEMPERATURES WILL BE MUCH COOLER AFTER TODAY.
FORECAST UPDATE
ISSUED AT 950 AM EDT SUN SEP 20 2026
FRONTAL BOUNDARY REMAINS ANCHORED OVER NORTH CENTRAL INDIANA THIS
MORNING WITH CONVECTION TO THE NORTH OF THE BOUNDARY OVER NORTHEAST
INDIANA AND NORTHWEST OHIO. FURTHER SOUTH ACROSS MUCH OF THE
FORECAST AREA IT WAS A MAINLY SUNNY START TO THE DAY. 13Z
TEMPERATURES WERE LARGELY IN THE 70S.
THE OVERALL FORECAST CAPTURES THE UNCERTAINTIES AND LOW CONFIDENCE
IN CONVECTIVE POTENTIAL FOR THE REST OF THE DAY AND LITTLE CHANGES
ARE NEEDED. THE BOUNDARY IS LIKELY TO DRIFT SOUTH INTO THE FORECAST
AREA INTO THIS AFTERNOON BUT A LACK OF FORCING AND BROAD RIDGING
ALOFT WILL LIMIT AND CONFINE ANY POTENTIAL CONVECTION TO THE
NORTHERN TIER OF CENTRAL INDIANA COUNTIES LIKELY IN AN ISOLATED TO
SCATTERED MANNER. WHILE EXTENSIVE CLOUD COVERAGE AND A SHIFT TO N/NE
FLOW AS THE BOUNDARY SLIPS SOUTH WILL KEEP TEMPERATURES IN THE UPPER
70S AND LOWER 80S OVER THE NORTHERN THIRD OF THE FORECAST AREA...
ANOTHER VERY WARM DAY IS ANTICIPATED TO THE SOUTH AS HIGHS RISE INTO
THE UPPER 80S AND LOWER 90S. DRIER AIR ADVECTING OFF THE OZARKS WILL
LIFT INTO THE OHIO VALLEY FOR THE AFTERNOON AND SHOULD PULL
DEWPOINTS DOWN OVER SOUTHERN PARTS OF CENTRAL INDIANA...PERHAPS INTO
THE LOWER 60S.
THE APPROACH OF A SURFACE WAVE ALONG THE BOUNDARY REMAINS THE
PRIMARY FOCUS FOR CONVECTION LATE TODAY AND INTO TONIGHT. DEFINITELY
POTENTIAL FOR A FEW CELLS TO PRODUCE DAMAGING WINDS WITH MODEST
AVAILABLE INSTABILITY BUT THE LACK OF SUBSTANTIAL SHEAR WILL KEEP
STORMS AT PULSE INTENSITY WITH LOCALLY HEAVY RAINFALL AGAIN
SERVING AS THE PRIMARY THREAT.
ZONE AND GRID UPDATES OUT.
DISCUSSION (TODAY THROUGH SATURDAY)
ISSUED AT 248 AM EDT SUN SEP 20 2026
EARLY THIS MORNING...
SOME UPPER ENERGY ALONG WITH THE OLD SURFACE FRONT WERE GENERATING
SOME SCATTERED SHOWERS ACROSS THE NORTHEASTERN HALF OF THE FORECAST
AREA.
AS AN ASSOCIATED SURFACE LOW ACROSS WESTERN ILLINOIS MOVES EAST AND
THE INITIAL UPPER ENERGY DEPARTS, THE SCATTERED SHOWERS SHOULD PUSH
EAST AND NORTH. MOST OF CENTRAL INDIANA SHOULD BE DRY BY 12Z.
TODAY AND TONIGHT...
ANOTHER UPPER WAVE WILL MOVE EAST AND PROVIDE FORCING THIS
AFTERNOON. MEANWHILE, THE SURFACE LOW WILL MOVE SOUTHEAST ACROSS
THE AREA.
WITH LITTLE OR WEAK FORCING ACROSS THE AREA THIS MORNING, WILL ONLY
HAVE SOME LOW POPS ACROSS THE FAR NORTH WHERE THE FRONT WILL START
OUT.
DURING THE AFTERNOON, AS THE SURFACE LOW MOVES THROUGH, FORCING WILL
INCREASE. THE LOW WILL DRAG THE FRONT SOUTH. THUS, EXPECT SCATTERED
TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP.
INTERESTINGLY, SOME DRIER AIR WILL GET ADVECTED INTO THE SOUTHERN
FORECAST AREA AHEAD OF THE SURFACE LOW. THIS MAY LIMIT CONVECTION
DEVELOPMENT THERE UNTIL THE SURFACE FRONT GETS CLOSER TOWARD 00Z.
CAMS SHOW A VARIETY OF SOLUTIONS, WHILE OTHER GUIDANCE FOCUSES RAIN
NORTH, NEAR AND BEHIND THE FRONT. GIVEN ALL THE ABOVE, WILL GO
LIKELY POPS IN THE FAR NORTH MID TO LATE AFTERNOON, TAPERING TO
SLIGHT CHANCE IN THE FAR SOUTH. CONFIDENCE ISN'T GREAT AS MESOSCALE
INFLUENCES AS WELL AS THE AFOREMENTIONED DRY AIR COULD CHANGE THINGS.
IF ENOUGH INSTABILITY BUILDS, CANNOT RULE OUT AN ISOLATED SEVERE
STORM WITH DAMAGING WINDS AHEAD OF THE FRONT. LOCALLY HEAVY RAIN
REMAINS A THREAT WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES.
RAIN CHANCES WILL CONTINUE TONIGHT AS THE FRONT CONTINUES TO TREK
SOUTH AND ADDITIONAL UPPER ENERGY MOVES THROUGH. OVERALL THOUGH
FORCING DOESN'T LOOK GREAT, SO WILL KEEP POPS NO HIGHER THAN CHANCE
CATEGORY.
A STRONG TEMPERATURE GRADIENT WILL EXIST AGAIN TODAY AS THE FRONT
MOVES SOUTH. TRIMMED BLENDED GUIDANCE FAR NORTH GIVEN THE EXPECTED
LOCATION OF THE FRONT AND CLOUDS/RAIN CHANCES. WENT NEAR 80 FAR
NORTH TO THE LOWER 90S SOUTH.
MONDAY AND TUESDAY...
UPPER WAVES ON MONDAY FOLLOWED BY AN APPROACHING UPPER LOW ON
TUESDAY WILL KEEP CHANCES FOR RAIN AROUND. THE HOT AIR WILL FINALLY
BE SOUTH OF THE AREA. HIGHS WILL BE IN THE UPPER 60S TO NEAR 80 ON
MONDAY WITH ONLY MID 60S TO LOWER 70S TUESDAY.
WEDNESDAY AND BEYOND...
THE FAR EAST MAY SEE AN ISOLATED SHOWER WEDNESDAY AS THE UPPER LOW
EXITS. OTHERWISE, HIGH PRESSURE WILL PROVIDE DRY WEATHER INTO NEXT
WEEKEND. TEMPERATURES WILL START OUT BELOW NORMAL, BUT THEY WILL
RETURN TO CLOSER TO NORMAL NEXT WEEKEND.
AVIATION (18Z TAF ISSUANCE)
ISSUED AT 1232 PM EDT SUN SEP 20 2026
IMPACTS:
- SCATTERED CONVECTION LATE TODAY THROUGH TONIGHT AND INTO MONDAY
MORNING
- DETERIORATING CEILINGS THIS EVENING WITH IFR CONDITIONS DEVELOPING
OVERNIGHT INTO MONDAY MORNING
- WINDS BECOMING NORTHEAST TONIGHT AND MONDAY
DISCUSSION:
A FRONTAL BOUNDARY BISECTS CENTRAL INDIANA EARLY THIS AFTERNOON WITH
WINDS ALREADY HAVING SHIFTED TO A NORTHERLY DIRECTION AT ALL BUT
KBMG. MID AND HIGH LEVEL CLOUDS WERE INCREASING OVER THE AREA...WITH
AN AXIS OF SCATTERED CU IN THE VICINITY OF THE FRONT. THE FRONT
WILL CONTINUE A SLOW SOUTHWARD DRIFT THROUGH THE REST OF THE
AFTERNOON AND WILL PASS THROUGH KBMG BY EARLY EVENING.
THE APPROACH OF A SURFACE WAVE ALONG THE BOUNDARY LATER TODAY WILL
LEAD TO AN INCREASE IN CONVECTIVE DEVELOPMENT EXTENDING INTO
TONIGHT. COULD SEE BRIEF RESTRICTIONS WITHIN ANY HEAVIER SHOWERS OR
STORMS BUT THE PRIMARY IMPACT TO AVIATORS WILL BE THE EXPANSION OF A
BROAD STRATUS DECK FROM NORTH TO SOUTH LATE THIS AFTERNOON INTO THE
EVENING. CEILINGS WILL EVENTUALLY SETTLE INTO THE IFR CATEGORY
OVERNIGHT WITH MODEL SOUNDINGS SHOWING SATURATED CONDITIONS IN THE
LOW LEVELS. CEILINGS MAY LIFT BACK INTO MVFR LEVELS BY LATE MORNING
MONDAY AS SHOWERS DECREASE IN COVERAGE. NORTHEAST WINDS WILL REMAIN
AROUND 10KTS TONIGHT AND MONDAY WITH THE POTENTIAL FOR PERIODIC
GUSTS AT KLAF.
IND WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE...RYAN
AVIATION...RYAN
DISCUSSION...50
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