953
FXUS63 KIWX 092321
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
721 PM EDT TUE JUN 9 2026
KEY MESSAGES
- HEAT AND HUMIDITY ON THE INCREASE THROUGH THURSDAY, WITH HIGHS
IN THE MID-UPPER 80S AND LOW 90S. HEAT INDICES ON WEDNESDAY
AND THURSDAY WILL BE AROUND 100 DEGREES. LOWS WILL BE IN THE
60S, LOW- MID 70S.
- DAILY CHANCES (GENERALLY 40-80 PERCENT) FOR SHOWERS AND STORMS
THIS WEEK. SEVERE WEATHER POTENTIAL EXISTS FOR BOTH WEDNESDAY
AND THURSDAY DURING THE LATE AFTERNOON-EVENING AND OVERNIGHT
HOURS. THERE IS HIGHER CONFIDENCE IN THE THREAT MATERIALIZING
THURSDAY EVENING INTO THE OVERNIGHT HOURS, ESPECIALLY WEST OF
INTERSTATE 69. DAMAGING WINDS AND LARGE HAIL ARE THE PRIMARY
THREATS. A TORNADO OR TWO MAY BE POSSIBLE, ESPECIALLY THURSDAY
EVENING/NIGHT.
- LOWER CHANCES (20-30 PERCENT) FOR SHOWERS AND STORMS RETURN
SUNDAY AFTERNOON INTO MONDAY, WITH TEMPS COOLING INTO THE LOW
TO MID 80S WITH DECREASED HUMIDITY.
DISCUSSION
ISSUED AT 212 PM EDT TUE JUN 9 2026
VERY WARM/MOIST AIRMASS REMAINS OVER THE AREA AND FURTHER
INCREASE IN HUMIDITY VALUES WITH LOW TO MID 70S TODAY AND
INCREASING INTO THE MID TO UPPER 70S BY TOMORROW. DID OPT TO
ADDRESS THIS HEAT/HUMIDITY (HIGHER HEAT INDICES) FOR WEDNESDAY
WITH AN ISSUANCE OF A HEAT ADVISORY FROM NOON UNTIL 8 PM. HEAT
INDICES WILL GENERALLY BE NEAR 100 BUT VALUES UP TO 103 WILL BE
POSSIBLE ESPECIALLY OUR EASTERN PORTIONS OF THE CWA. UNCERTAINTY
ON IF CLOUDS MAY KEEP THE HEAT INDICES A BIT BLUNTED BUT WE
WOULD CERTAINLY BE SPLITTING HAIRS AS IT WILL BE MUGGY AND VERY
UNCOMFORTABLE AND WITH THIS BEING THE FIRST BOUT OF DECENT
HEAT/HUMIDITY THIS SEASON WILL BE A BIT MORE TAXING ON EVERYONES
SYSTEM.
THE UNSTABLE AIRMASS HAS ALSO ALLOWED FOR ANY PERTURBATIONS SUCH
AS THIS MORNING'S SHORTWAVE TO FIRE OFF BOUTS OF CONVECTION AND
WILL CONTINUE TO DO SO OVER THE NEXT SEVERAL DAYS. THE NATURE
OF THIS DEFINITELY HAS MADE FOR A DIFFICULT CONVECTIVE FORECAST
ESPECIALLY WITH THE TIMING AND COVERAGE. GUIDANCE ALSO SEEMS TO
BE STRUGGLING WITH NO REAL CONSENSUS HAD BETWEEN CONVECTIVE
ALLOWING MODELS. FOR THE SHORT TERM THE LACK OF AVAILABLE
SHEAR/FORCING MECHANISMS HAVE LED TO MORE OF THE PULSE VARIETY
OF STORMS WITH THE MAIN IMPACTS IN THE FORM OF HEAVY DOWNPOURS
IN THE VERY TROPICAL-ESQUE ENVIRONMENT ALONG WITH A FEW STRONG
OUTFLOW GUSTS ACCOMPANYING ANY COLLAPSING CORES. A WEAK
SHORTWAVE LOOKS TO MOVE THROUGH LATER TODAY AND WILL SEE AN
UPTICK IN THUNDERSTORM/SHOWER ACTIVITY OVERNIGHT TONIGHT WITH
LESS THAN IDEAL DIURNAL TIMING WHICH SHOULD ALSO MITIGATE STORM
STRENGTH. ANOTHER SHORTWAVE TRANSVERSING THROUGH THE AREA LATE
IN THE DAY TOMORROW WILL BRING ANOTHER ROUND OF CONVECTION
HOWEVER, THE EXACT TIMING HAS BEEN VERY DIFFICULT TO NAIL DOWN
AND ANY MORNING CONVECTION COULD INTERFERE WITH THE AFTERNOON
SET UP ESPECIALLY WITH INCREASED CLOUDS. AS OF RIGHT NOW THE 6
PM THROUGH MIDNIGHT EDT TIME FRAME LOOKS LIKE THE BEST BET FOR
TIMING. SPC CURRENTLY HAS OUR AREA UNDER A MARGINAL TO SLIGHT
RISK FOR SEVERE THUNDERSTORMS WITH THE BETTER CHANCES OVER THE
NORTHWESTERN PARTS OF THE CWA. MAIN THREATS WILL BE GUSTY WINDS
AND HAIL. SOME OF THE CONVECTION LOOKS TO CONTINUE INTO THURSDAY
MORNING.
STILL VERY DIFFICULT TO LOCK DOWN THE EXACT TIMING BUT LATEST
GUIDANCE HAS A COOL FRONT APPROACHING FROM THE NORTHWEST BY
THURSDAY EVENING. 9PM UNTIL 3 AM EDT LOOKS TO BE THE BEST PERIOD
FOR THIS FRONT TO PUSH THROUGH. THE COOL FRONT WILL PROVIDE A
BETTER FORCING MECHANISM AS WELL AS PROVIDE BETTER SHEAR
PROFILES. SOME QUESTION AS TO IF ANY CONVECTION EARLIER IN THE
DAY MAY AFFECT THE ENVIRONMENT INTO THE EVENING WHICH COULD
MITIGATE THE STRENGTH AND COVERAGE OF STORMS ALONG THE FRONTAL
BOUNDARY. BUT AS OF RIGHT NOW SPC DOES HAVE OUR AREA IN A
MARGINAL TO ENHANCED RISK FOR SEVERE STORMS WITH THE STRONGER
STORMS POSSIBLE AGAIN OVER THE NORTHWESTERN PORTIONS OF THE
CWA. ALL THREATS LOOK TO BE ON THE TABLE WITH THIS EVENT
INCLUDING A FEW TORNADOES BEING POSSIBLE.
COOLER AND MOST IMPORTANTLY A DRIER AIRMASS MOVES IN BEHIND THE
FRONT ON FRIDAY AND SATURDAY. HIGHS IN THE UPPER 70S TO LOW/MID
80S EXPECTED WITH NO PRECIPITATION FORECAST. HOWEVER, ANOTHER
COOL FRONT APPROACHES THE AREA BY SUNDAY MORNING BRINGING
ANOTHER SHOT OF COOLER AIR WHILE INCREASING CHANCES FOR SOME
GARDEN VARIETY SHOWERS/THUNDERSTORMS ON SUNDAY INTO MONDAY.
ANOTHER TROUGH DROPS SOUTHWARD INTO THE CENTRAL CONUS ON
TUESDAY WHICH WILL KEEP A SLIGHT THREAT OF SHOWERS/THUNDERSTORMS
FOR THE AREA IN PLAY.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 720 PM EDT TUE JUN 9 2026
PASSING SHORTWAVE AND MOIST LOW LEVELS SUPPORTING SCATTERED
THUNDERSTORMS FOR A FEW MORE HOURS. COVERAGE IS EXPECTED TO
REMAIN ON THE LOW SIDE AND CONFIDENCE IN IMPACTS IS THEREFORE
TOO LOW FOR ANYTHING MORE THAN A PROB30 MENTION. MVFR STRATUS
AND BR MAY ALSO DEVELOP AT KSBN LATE TONIGHT BUT CONFIDENCE IN
THAT IS ALSO LOW. NEXT CHANCE OF STORMS ARRIVES WEDNESDAY
EVENING LIKELY AROUND OR JUST AFTER 00Z.
IWX WATCHES/WARNINGS/ADVISORIES
IN...HEAT ADVISORY FROM NOON TO 8 PM EDT WEDNESDAY FOR INZ006>009-
015-017-018-022>027-032>034-116-216.
OH...HEAT ADVISORY FROM NOON TO 8 PM EDT WEDNESDAY FOR OHZ001-002-
004-005-015-016-024-025.
MI...HEAT ADVISORY FROM NOON TO 8 PM EDT WEDNESDAY FOR MIZ081.
MARINE...NONE.
DISCUSSION...ANDERSEN
AVIATION...AGD
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