814
FXUS63 KIWX 161813
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
213 PM EDT WED SEP 16 2026
KEY MESSAGES
- 1 OR 2 ADDITIONAL ROUNDS OF SHOWERS AND STORMS ARE POSSIBLE,
MAINLY LATE TONIGHT INTO THURSDAY MORNING. HEAVY RAIN AND
ASSOCIATED FLOODING POTENTIAL ARE THE GREATEST CONCERN,
ESPECIALLY IN AREAS THAT EXPERIENCED HEAVY RAIN OVER THE PAST
24 HOURS.
- DRY AND LESS HUMID CONDITIONS ON FRIDAY FOLLOWED BY RENEWED
OPPORTUNTIES FOR RAIN AND STORMS THIS WEEKEND.
DISCUSSION
ISSUED AT 212 PM EDT WED SEP 16 2026
A SMALL WINDOW OF DRIER CONDITIONS SHOULD UNFOLD FOR THE NEXT 6 TO 9
HOURS FOR MANY AREAS IN THE WAKE OF THE DEPARTING MCV AND ASSOCIATED
PRECIP. UPSTREAM ACROSS IL A FEW SHOWERS ARE DEVELOPING AND CAN'T
RULE OUT WIDELY SCATTERED SHOWERS AND STORMS LATER TODAY INTO THIS
EVENING IN AREAS THAT SEE LIMITED CLEARING (MAINLY SE). SPC HAS
MAINTAINED THE MARGINAL RISK FOR SEVERE IN OUR SE WITH A LOW CHANCE
FOR SOME LOCALLY GUSTY WINDS FROM ANY MORE ORGANIZED STORMS THAT
PRODUCE WET MICROBURSTS, MUCH LIKE YESTERDAY.
THE GREATER CONCERN LIES WITH FLOODING POTENTIAL LATER TONIGHT INTO
THURSDAY. MOST AREAS ACROSS N INDIANA AND TO A LESSER EXTENT NW OHIO
HAVE EXPERIENCED MULTIPLE ROUNDS OF SHOWERS AND STORMS AND ALL SIGNS
POINT TOWARDS ANOTHER ROUND OVERNIGHT DEVELOPING UPSTREAM AND MOVING
ESE ALONG THE QUASI STATIONARY BOUNDARY THAT WILL BE DRAPED ACROSS
THE AREA. PWATS CONTINUE AROUND 2" AND PROBABLY EVEN HIGHER WITH NO
MAJOR CHANGE IN AIR MASS EXPECTED UNTIL LATER THURSDAY INTO FRIDAY.
WPC HAS ALL BUT OUT MI COUNTIES IN A SLIGHT RISK FOR EXCESSIVE
RAINFALL, WHICH IS VERY REASONABLE GIVEN THE SETUP. WHILE CONFIDENCE
IS SOMEWHAT HIGHER ON AT LEAST PARTS OF THE AREA BEING IMPACTED,
SOME CAMS (ESPECIALLY THE HRRR) DEVELOP 2 ROUNDS WITH ONE SHORTLY
AFTER 6Z ACROSS SOUTHERN AREAS AND THEN THE UPSTREAM DEVELOPMENT
ARRIVING TOWARDS 12Z THU. WHILE A FLOOD WATCH COULD BE EASILY
JUSTIFIED GIVEN THE WET CONDITIONS AND POTENTIAL FOR ANOTHER 1 TO AS
MUCH AS 3 INCHES IN SOME SPOTS, CONFIDENCE ON TIMING AND LOCATION OF
THE HEAVIEST PRECIP REMAINS LOW ENOUGH TO HOLD OFF ON ANY HEADLINES.
POPS HAVE BEEN ADJUSTED TO REFLECT TRENDS WITH A LARGER,
BROADBRUSHED LIKELY AREA LATE TONIGHT INTO THURSDAY MORNING WITH
PRECIP THEN ENDING FROM WEST TO EAST.
LATE THURSDAY INTO FRIDAY IT STILL APPEARS THAT MUCH, IF NOT ALL OF
THE AREA SHOULD SEE A BREATHER IN RAIN CHANCES ALONG WITH SOMEWHAT
LOWER HUMIDITY. LATE FRIDAY NIGHT INTO SAT THIS CHANGES AS YET
ANOTHER WAVE MOVES TOWARDS THE REGION WHICH FORCES THE FRONT BACK
NORTH AND BRINGS RAIN CHANCES WITH IT. HYDRO CONCERNS WILL LIKELY
REMAIN GIVEN THE SMALL WINDOW OF DRYING.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 205 PM EDT WED SEP 16 2026
PRIMARY AVIATION WEATHER CONCERN WILL BE ON CIG TRENDS AND
POTENTIAL OF ADDITIONAL CONVECTION THROUGH THE PERIOD. AN MCV
TYPE FEATURE IS TRACKING ACROSS NORTHERN INDIANA THIS AFTERNOON
WITH A LARGE PORTION OF THE RAINFALL HAVING VACATED THE AREA. A
LULL IN THIS FORCING IS EXPECTED THIS AFTERNOON BUT CONTINUED
MOISTURE TRANSPORT AND POSITIVE LOW LEVEL THETA-E ADVECTION
COULD GIVE RISE TO ADDITIONAL ISOLATED-SCATTERED SHOWERS AND
THUNDERSTORMS LATE IN THE AFTERNOON. WITH SFC BOUNDARY SOUTH OF
THE TERMINALS, IFR/MVFR CIGS HAVE BEEN NOTED ACROSS THE AREA AND
WOULD EXPECT THIS POTENTIAL TO LINGER ANOTHER HOUR OR TWO BEFORE
BETTER MIXING TEMPORARILY IMPROVES CONDITIONS. ANOTHER SHORT
WAVE ROUNDING THE FLATTENED RIDGE FROM THE CORN BELT SHOULD HELP
ACTIVATE ANOTHER ROUND OF SHOWERS AND STORMS ACROSS IA/IL
TONIGHT, POSSIBLY AFFECTING NORTHERN INDIANA AFTER 08Z TONIGHT
INTO EARLY THURSDAY MORNING. WILL REFRAIN FROM THUNDER MENTION
AT THIS TIME GIVEN UNCERTAINTY IN TIMING AND INSTABILITY
MAGNITUDES, BUT THIS WILL NEED TO BE MONITORED IN UPCOMING
FORECASTS. HIGHER RES GUIDANCE ALSO CONTINUES TO FAVOR IFR CIGS
REDEVELOPING TONIGHT TO THE NORTH OF THE BOUNDARY WITH ONLY SLOW
IMPROVEMENT TOWARD THE END OF THIS FORECAST VALID PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...FISHER
AVIATION...MARSILI
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