267
FXUS63 KIWX 281838
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
238 PM EDT SUN JUN 28 2026
KEY MESSAGES
- EXTREME HEAT WARNING IN EFFECT MONDAY AFTERNOON INTO THURSDAY
EVENING FOR AN EXTENDED PERIOD OF HIGH HEAT INDICES AND
LIMITED NIGHTTIME COOLING.
- HEAT MAY REMAIN A CONCERN FRIDAY, BUT CHANCES FOR SHOWERS AND
THUNDERSTORMS BEGIN TO INCREASE RESULTING IN LOWER CONFIDENCE
ON THE AMOUNT OF IMPACTS.
DISCUSSION
ISSUED AT 238 PM EDT SUN JUN 28 2026
BLUF...AFTER EXTENSIVE COLLABORATION WITH SURROUNDING OFFICES, WE
HAVE DECIDED TO UPGRADE TO AN EXTREME HEAT WARNING FOR THE SAME
VALID PERIOD AS THE WATCH. WILL BREAK DOWN THE PROS AND CONS
SHORTLY. WE WANT TO REITERATE THAT REGARDLESS OF THE TYPE OF HEAT
RELATED HEADLINE, THEY ALL CONVEY THE SAME THING...A FOCUS ON THE
IMPACTS OF THE HEAT TO EVERYONE. IN ADDITION TO SENSITIVE
POPULATIONS, EVEN THOSE THAT ROUTINELY WORK OUTSIDE OR HAVE A/C WILL
BE IMPACTED
WARMING TODAY HAS BEEN SOMEWHAT LIMITED BY HIGH CLOUDS BLOWOFF FROM
A PERSISTENT MCS TO OUR WEST AS WELL AS SOME CU POPPING HERE AND
THERE ACROSS THE AREA. RADAR AND SATELLITE DATA SHOWING THE COMPLEX
FINALLY BEGINNING TO WEAKEN. WHILE THE REMNANTS COULD BRING A QUICK
SHOWER TO NORTHERN PORTIONS OF THE AREA LATER THIS AFTERNOON OR
EARLY EVENING MODELS GENERALLY LEAN TOWARD NO IMPACTS SO POPS WILL
BE LEFT BELOW 15%. ADDITIONAL UPSTREAM COMPLEX ARE EXPECTED OVER THE
NEXT DAY OR 2, BUT SHOULD REMAIN WELL NORTH OF THE FORECAST AREA.
WE THEN TURN OUR ATTENTION TO THE BIGGER STORY OF THE DRAMATIC
ARRIVAL OF SUMMER AND EXTENDED PERIOD OF INCREASED HEAT AND
HUMIDITY. A MIXTURE OF HEADLINES SURROUND US WHICH MAY POSE
CHALLENGES TO OUR MEDIA PARTNERS IN MESSAGING. MONDAY WILL BE THE
"COOLEST" OF THE NEXT SEVERAL DAYS WITH MANY OFFICES LEANING TOWARD
HANDLING THIS WITH A HEAT ADVISORY AND THEN LOOK AT A WATCH OR
EVENTUAL WARNING IN THE LATER PERIODS. FOR OUR AREA, EVEN THOUGH THE
SAME CONCERNS EXIST, IT WAS DECIDED TO KEEP MESSAGING SIMPLE AND
JUST UPGRADE TO A WARNING FOR THE EXTENDED PERIOD OF IMPACTS WITH
HEAT INDICIES AOA 100 DEGREES. THERE ARE FACTORS THAT COULD CAUSE
TRUE CRITERIA FROM BEING MET AT TIMES BOTH MONDAY AND THURSDAY, BUT
IT IS THE CUMULATIVE EFFECTS OF HEAT AND HUMIDITY, COMBINED WITH
LIMITED OVERNIGHT COOLING, THAT POSE THE GREATEST DANGER. SOME MODEL
TRENDS ARE INDICATING THE UPPER RIDGE MAY NOT FULLY SETTLE OVER THE
AREA AND COULD SHIFT EAST A BIT FASTER TO ALLOW AT LEAST THE CHANCE
FOR A BIT OF CONVECTION. FRIDAY MAY NEED HEADLINES AS WELL, BUT
CONCERNS FOR EITHER CONVECTIVE DEVELOPMENT ACROSS THE AREA OR
UPSTREAM COMPLEXES PROPAGATING INTO THE REGION LEAD TO GREATER
UNCERTAINTY. WITH THE FOCUS ON THE HEAT, LITTLE WILL BE ADDRESSED
FOR NOW ON THE HOLIDAY WEEKEND OTHER THAN IT WILL REMAIN ON THE
WARMER SIDE WITH ADDITIONAL POTENTIAL FOR SHOWERS AND STORMS AT
TIMES.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 129 PM EDT SUN JUN 28 2026
MVFR CIGS TONIGHT WITH THE PRESENCE OF A WEAK WARM FRONTAL
BOUNDARY THAT IS NORTHWEST TO SOUTHEAST ORIENTATED ACROSS THE
CWA WILL BEGIN TO CLEAR OUT OVERNIGHT LEAVING VFR CONDITIONS
WITH JUST HIGH CLOUDS FROM SOME CONVECTIVE BLOWOFF FROM THE
WEST. DIURNAL CLOUDS AROUND 5000 FT WILL DEVELOP BETWEEN 15-17Z
MON BUT WILL REMAIN INERT WITH VERY STRONG CAPPING INVERSION IN
PLACE. DIURNAL SOUTHEASTERLY WINDS ALSO BECOME BREEZY IN THE
AFTERNOON ON MONDAY MAINLY FOR KSBN DUE TO A LAKE BREEZE
INTERACTION BUT A SLIGHT UPTICK WITH THE SURFACE WARMING
ELSEWHERE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...EXTREME HEAT WARNING FROM 2 PM EDT /1 PM CDT/ MONDAY TO 8 PM
EDT /7 PM CDT/ THURSDAY FOR INZ005>009-012>015-017-018-
020-022>027-032>034-103-104-116-203-204-216.
OH...EXTREME HEAT WARNING FROM 2 PM MONDAY TO 8 PM EDT THURSDAY FOR
OHZ001-002-004-005-015-016-024-025.
MI...EXTREME HEAT WARNING FROM 2 PM MONDAY TO 8 PM EDT THURSDAY FOR
MIZ078>081-177-277.
MARINE...NONE.
DISCUSSION...FISHER
AVIATION...ANDERSEN
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