986
FXUS63 KIWX 022213
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
613 PM EDT WED SEP 2 2026
KEY MESSAGES
- HEAT AND HUMIDITY CONTINUE THROUGH THURSDAY WITH PEAK HEAT INDICES
AROUND 100 DEGREES, ESPECIALLY ALONG AND SOUTH OF US 30.
- 20-30% CHANCES OF THUNDERSTORMS THURSDAY, BEGINNING PRIOR TO
DAYBREAK MAINLY NORTH OF I-80/I-90 THEN EXPANDING AREA-WIDE
BY THE AFTERNOON AND EVENING. STORMS MAY PRODUCE DAMAGING
WINDS. LOW CONFIDENCE AT THIS TIME.
- 30-60% CHANCES FOR SHOWERS AND STORMS AREA-WIDE LATE THURSDAY
EVENING INTO FRIDAY MORNING.
DISCUSSION
ISSUED AT 110 PM EDT WED SEP 2 2026
HEAT AND HUMIDITY PERSIST TODAY WITH HIGH TEMPERATURES EXPECTED TO
BE IN THE UPPER 80S TO LOW 90S. THE UPPER LEVEL RIDGE IS DIRECTLY
OVER THE GREAT LAKES WITH A LARGE AREA OF SURFACE HIGH PRESSURE
ANCHORED OVER THE SOUTHEASTERN CONUS. AMPLE WAA WILL CONTINUE TO
BOOST TEMPERATURES WELL ABOVE AVERAGE FOR EARLY SEPTEMBER. INCREASED
MOISTURE RETURN STEMMING FROM THE GULF WILL ALSO ALLOW FOR DEWPOINTS
IN THE MID 70S TO CONTINUE. THE HEAT ADVISORY CONTINUES FOR THE
ENTIRE FORECAST AREA UNTIL 8 PM EDT; IT HAS BEEN EXTENDED TO LAST
UNTIL 8 PM EDT THURSDAY FOR COUNTIES ALONG AND SOUTH OF US 30 IN
INDIANA AND OHIO. CONFIDENCE IS GROWING THAT HEAT INDICES WILL BE AT
OR SLIGHTLY ABOVE 100 DEGREES TOMORROW IN THE VICINITY OF THE US 30
CORRIDOR, WHERE THERE ARE LOWER CHANCES FOR CONVECTION AND/OR
CLOUDS. WE SHOULD STAY MAINLY DRY TODAY; ORIGINALLY THERE WAS A LOW
CHANCE FOR A STRAY STORM BUT GIVEN THAT AN OUTFLOW MORNING FROM
REMNANT MORNING UPSTREAM CONVECTION IS ALREADY COMING THROUGH AND
THERE IS A DOWNWARD TREND ON VISIBLE SATELLITE IMAGERY FOR CLOUD
COVER, HAVE OPTED TO KEEP THE AREA DRY TODAY AND TONIGHT.
AS THE UPPER LEVEL RIDGE BEGINS TO FLATTEN, OUR LOWER MICHIGAN
COUNTIES MAY BE ON THE PERIPHERY. HAVE MAINTAINED 15-20% CHANCES FOR
ISOLATED CONVECTION BETWEEN 06-18Z MAINLY NORTH OF I-80/I-90, WITH
BROADER 15-20% EXPANDING INTO THE ENTIRE AREA AFTER 18Z THURSDAY
IN LINE WITH THE 12Z SUITE OF CAMS. THURSDAY'S POPS ARE HIGHLY
CONDITIONAL DEPENDING ON WHERE/IF ANY OUTFLOWS OR SHORTWAVES
SETUP. DEPENDING ON HOW MUCH THE RIDGE FLATTENS AND WHERE THE
BEST CONVECTIVE ENVIRONMENT SETS UP, OUR AREA MAY SEE AN ACTIVE
PATTERN TO END THE WEEK INTO THE WEEKEND AHEAD. HI- RES AND
MEDIUM RANGE GUIDANCE SUGGESTS ONE OR MULTIPLE MCSS COULD MOVE
THROUGH THE AREA LATE THURSDAY NIGHT THROUGH SATURDAY. MODEL
GUIDANCE CONTINUES TO BE ALL OVER THE PLACE IN REGARDS TO TIMING
AND EXACT LOCATION OF STORMS THURSDAY THROUGH THE WEEKEND,
HOWEVER, IN GENERAL, OUR HOT AND HUMID ENVIRONMENT OVERHEAD WILL
BE SUPPORTIVE FOR CONVECTION. WE SHOULD HAVE AMPLE INSTABILITY
AND MOISTURE TO WORK WITH BUT OTHER ELEMENTS SUCH AS SHEAR
REMAIN IN QUESTION DUE TO CONSIDERABLE UNCERTAINTY ON HOW THE
LARGER SYNOPTIC EVOLUTION.
AS MENTIONED IN THE PREVIOUS DISCUSSION, THERE IS A LARGE SPREAD ON
THE LONG RANGE TEMPERATURES AND EVOLUTION OF THE UPPER LEVEL RIDGE.
WHILE THE NBM HAS HIGHS NEAR 80 BY LATE IN THE WEEKEND INTO EARLY
NEXT WEEK, THERE IS STILL ABOUT A 10 DEGREE SPREAD IN GUIDANCE
RANGING FROM 75-85 DEGREES FOR HIGHS. WITH TROUGHING EXPECTED TO
SETUP OVER THE WESTERN CONUS, THE UPPER LEVEL RIDGE MAY BRIEFLY
DIMINISH OVER THE WEEKEND AND THEN BUILD BACK INTO THE AREA EARLY
INTO THE MIDDLE OF NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 612 PM EDT WED SEP 2 2026
VFR CONDITIONS AND SOUTHWEST WINDS GENERALLY IN THE 5-10 KT
RANGE WILL GENERALLY PERSIST THROUGH THE TAF CYCLE. WILL HAVE
MONITOR CONVECTIVE TRENDS LATER TONIGHT INTO TOMORROW AS SOME
ELEVATED CONVECTION COULD BRIEFLY SNEAK INTO NORTHERN IN.
HOWEVER, POINT CHANCES REMAIN TOO LOW (5-20%) FOR A MENTION IN
THE TAF AT THIS TIME.
IWX WATCHES/WARNINGS/ADVISORIES
IN...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
INZ005>009-103-104-203-204.
HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ THURSDAY FOR
INZ012>015-017-018-020-022>027-032>034-116-216.
OH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR OHZ001-002-004-
005.
HEAT ADVISORY UNTIL 8 PM EDT THURSDAY FOR OHZ015-016-024-025.
MI...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ078>081-177-
277.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...STEINWEDEL
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