638
FXUS63 KIWX 151745
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
145 PM EDT WED JUL 15 2026
KEY MESSAGES
- A HEAT ADVISORY IS IN EFFECT FOR TODAY AND THEN FOR A PORTION
OF THE AREA THURSDAY. THE THREAT FOR HOT CONDITIONS CONTINUES
THROUGH THE END OF THE WEEK.
- HAZY TO SMOKY CONDITIONS POSSIBLE LATER TODAY FROM CANADIAN WILDFIRE
SMOKE.
- CHANCES FOR SHOWERS AND STORMS RETURN LATE THIS WEEK INTO THIS
WEEKEND, PRIMARILY DURING THE AFTERNOON AND EVENING HOURS.
DISCUSSION
ISSUED AT 142 PM EDT WED JUL 15 2026
A BACKDOOR FRONT, WHICH HAS HAD SOME UNCERTAINTY IN PREVIOUS MODEL
RUNS AROUND HOW FAR IT GETS INTO THE AREA, IS BEING MODELED AS
SLOWLY PUSHING INTO THE AREA TONIGHT INFLUENCING THURSDAY'S
TEMPERATURES AND DEW POINTS TO THE COOLER AND DRIER SIDE OF THE
SCALE. TODAY'S DEW POINTS ARE BEING MODELED AS SURPASSING 70 DEGREES
AND ACHIEVING THE HIGHEST VALUES OF THIS TIME: REACHING 75 DEGREES.
AT THE SAME TIME, TODAY'S 850 MB TEMPERATURES REACH AT LEAST 20C TO
POTENTIALLY AS HIGH AS 23C (WHICH CAN LEAD TO 95F HIGH TEMPS ON A
DAY WITH MAXIMUM MIXING) ON THE ECMWF. FOR THURSDAY, DRIER DEW
POINTS IN THE 60S TO POTENTIALLY MORE LIKE UPPER 50S WORK IN AS 850
MB TEMPS BECOME MORE LIKE 19 TO 20C. BECAUSE THE RIDGE CENTER WORKS
MORE SOUTHEASTWARD INTO THE SOUTHEASTERN US AND MID ATLANTIC AREA, A
SHORTWAVE LOOKS TO WRAP AROUND THE WESTERN EDGE OF THE RIDGE CENTER
AND GETS INTO THE SOUTHWESTERN PORTION OF THE AREA POTENTIALLY BY
THE END OF THE DAY THURSDAY, WHICH COULD AFFECT THE AREA MOST
CONDUCIVE TO HIGHER HEAT INDICES (THAT COMBO OF TEMPS AND DEW
POINTS). EVEN STILL, GIVEN CONTINUED HEAT, THOUGHT IT PRUDENT TO
ISSUE AN ADVISORY FOR AREAS MOST POSSIBLE TO REACH 100 DEGREES ON
THURSDAY, OUR SOUTHERN TWO TIERS OF COUNTIES IN IN. IT ALSO POSSIBLE
THAT SATURDAY, OUT IN FRONT OF A COLD FRONT, ENDS UP WITH A HEAT
ADVISORY, BUT LESS CERTAINTY EXISTS WITH THE POTENTIAL FOR SHOWERS
AND STORMS. GIVEN HOW DRY WE'VE BEEN AND HOW WARM THE LOW TO MID
LEVELS ARE, PERHAPS A CAP WILL EXIST TO HOLD OFF CONVECTION.
THE SHORTWAVE MENTIONED FOR THURSDAY CONTINUES TO MOVE THROUGH FROM
WEST TO SOUTH FOR FRIDAY AS A TROUGH MOVES NORTH TO SOUTHEAST IN THE
NORTHEAST CONUS. THIS MAKES THE AREA MORE CONDUCIVE AT LEAST FOR
AFTERNOON POP CONVECTION. ENOUGH INSTABILITY APPEARS TO BE AROUND
MAKE THUNDERSTORMS POSSIBLE, BUT WIND SHEAR APPEARS TO BE THE
LIMITING FACTOR FOR SEVERE WEATHER. A LOW LEVEL JET MOVES INTO THE
AREA ON SATURDAY AHEAD OF A COLD FRONT, WHICH MAY INCREASE THE
SEVERE WEATHER CHANCE, BUT COLD POOL STRENGTH AND CELL INTERACTIONS
WILL PROBABLY BE THE MAIN FACTOR IN CREATING SEVERE WEATHER AS
OPPOSED TO NORMAL SHEAR-INDUCED ORGANIZATION. ANOTHER TROUGH COMES
THROUGH TUESDAY OF NEXT WEEK AND A LOW LEVEL JET IS AROUND THE AREA
TO POTENTIAL PROVIDE ORGANIZATION, BUT AGAIN SHEAR MAGNITUDE APPEARS
WEAK. TIMING OF THE FROPA AND STATE OF THE WARM SECTOR ALSO STILL
NEED MORE AGREEMENT.
HIGH PRESSURE LOOKS TO KEEP THE AREA DRY SUNDAY AND POTENTIALLY
MONDAY.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 109 PM EDT WED JUL 15 2026
SURFACE HIGH PRESSURE REMAINS IN PLACE RESULTING IN DIURNALLY-
DRIVEN WINDS SHY OF 10 KNOTS FOLLOWED BY LIGHT AND VARIABLE WIND
OVERNIGHT. WIND APPEARS TO BE LESS THAN 5 KNOTS FOR MOST OF
THURSDAY, WITH A SLIGHTLY PREFERENCE FOR A NORTHERLY WIND.
WILDFIRE SMOKE IS THE WILDCARD WITHIN THE TAFS AS A THICK PLUME
IS NOTED NORTH OF THE TERMINALS, ACROSS THE THUMB OF MICHIGAN.
THIS IS FORECAST TO DROP SOUTH OVER THE NEXT 12 HOURS AND COULD
RESULT IN SURFACE-LEVEL HAZE BY DAYBREAK.
IWX WATCHES/WARNINGS/ADVISORIES
IN...HEAT ADVISORY UNTIL 8 PM EDT /7 PM CDT/ THIS EVENING FOR
INZ005>009-012>015-017-018-020-022>027-032>034-103-104-
116-203-204-216.
AIR QUALITY ALERT FROM MIDNIGHT EDT /11 PM CDT/ TONIGHT TO
MIDNIGHT EDT /11 PM CDT/ THURSDAY NIGHT FOR INZ005>009-
012>015-017-018-022>027-032>034-104-116-204-216.
HEAT ADVISORY FROM NOON TO 8 PM EDT THURSDAY FOR INZ013-015-
020-022>027-032>034.
AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR INZ020.
AIR QUALITY ALERT UNTIL MIDNIGHT CDT THURSDAY NIGHT FOR INZ103-
203.
OH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR OHZ001-002-004-
005-015-016-024-025.
MI...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MIZ078>081-177-
277.
AIR QUALITY ALERT UNTIL MIDNIGHT EDT THURSDAY NIGHT FOR
MIZ078>081-177-277.
MARINE...NONE.
DISCUSSION...ROLLER
AVIATION...BROWN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page