140
FXUS63 KIWX 081753
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
153 PM EDT WED JUL 8 2026
KEY MESSAGES
- QUIET TODAY WITH HIGHS IN THE MID/UPPER 80S.
- THUNDERSTORMS ARE LIKELY THURSDAY EVENING AND OVERNIGHT.
ISOLATED SEVERE STORMS AND HEAVY RAIN ARE POSSIBLE WITH THE
BEST CHANCES SOUTH OF US-30.
- LOW CHANCES FOR A FEW STORMS FRIDAY AND SATURDAY BUT TURNING
DRY AND HOT AGAIN NEXT WEEK.
DISCUSSION
ISSUED AT 151 PM EDT WED JUL 8 2026
THE MAIN FORECAST CONCERN OVER THE NEXT 24 TO 48 HOURS CONTINUES TO
BE THE INCREASED POTENTIAL FOR CONVECTION W/ THE PASSAGE OF A WEAK
MID-LEVEL SHORT WAVE FROM THURSDAY EVENING THROUGH FRIDAY AM. LITTLE
HAS CHANGED W/ REGARD TO THE OVERALL FORECAST THINKING AS CONFIDENCE
HAS INCREASED IN A MORE SOUTHEASTWARD TRAJECTORY OF THE SHORT WAVE,
LEAVING THE BULK OF OUR CWA WITH VERY MEAGER INSTABILITY/SHEAR
PROFILES WHILE THE MOST RIPE THETA-E AIR MASS (AND BETTER WIND
PROFILES) REMAIN WELL TO THE SOUTH. STILL THINK THE FOCUS AREA WILL
REMAIN SOUTH OF US-30, BUT STILL SOME UNCERTAINTY HERE W/ MESOSCALE
INFLUENCES. AS SUCH, NOT COMFORTABLE TRENDING POPS DOWNWARD AT THIS
POINT EVEN THOUGH IT SEEMS CENTRAL AND SOUTHERN IL/IN MAY BE IN A
MORE FAVORABLE POSITION. THERE REMAIN SOME HINTS AT A NOCTURNAL MCS
TRACKING ACROSS THE REGION OVERNIGHT, POSSIBLY IMPACTING A SET OF
OUR SOUTHERN ZONES. WOULD ANTICIPATE HEAVY RAIN AND LOCALIZED
FLOODING TO BE THE PRIMARY HAZARD FOR THIS EVENT, BUT A COUPLE
STRONG TO MARGINALLY SEVERE STORMS CANNOT BE RULED OUT. /HAMMER
PREVIOUS DISCUSSION (ISSUED AT 138 AM EDT WED JUL 8 2026):
ANOTHER TRANQUIL WEATHER DAY TODAY AS BROAD MID/UPPER LEVEL RIDGING
AND LOW LEVEL THETA-E SINK REMAIN CENTERED DIRECTLY OVER OUR CWA.
SOME PATCHY FOG IS POSSIBLE THIS MORNING BUT LIMITED NEAR-SURFACE
MOISTURE AND SOME CLOUDS IN THE SE WILL KEEP COVERAGE AND DENSITY IN
CHECK. HIGHS TODAY LIKELY VERY SIMILAR TO YESTERDAY THOUGH PERHAPS A
DEGREE OR TWO WARMER GIVEN SOME SUBTLE WAA AND AIRMASS MODIFICATION
UNDER STRONG JULY SUN. LOWS TONIGHT ONLY IN THE MID/UPPER 60S DUE TO
SLOWLY INCREASING LOW LEVEL MOISTURE AND A SLIGHTLY WARMER AFTERNOON.
MAIN FORECAST CONCERN IS THUNDERSTORM POTENTIAL THU EVENING/
OVERNIGHT. A WEAK (CONVECTIVELY MODIFIED) MIDLEVEL SHORTWAVE WILL
APPROACH THE AREA THU EVENING. A MODEST INCREASE IN LOW LEVEL SW
FLOW AHEAD OF THIS WAVE WILL BRING BETTER MOISTURE INTO THE REGION
BUT IT'S WORTH NOTING FAR BETTER THETA-E SURGE REMAINS FOCUSED OVER
CENTRAL AND SOUTHERN IL/IN. MIDLEVEL LAPSE RATES REMAIN PALTRY AND 0-
1KM MLCAPE VALUES LIKELY STRUGGLE TO GET MUCH ABOVE 1000 J/KG.
WIND/SHEAR PROFILES ARE ALSO LIGHT WITH ONLY AROUND 20 KTS OF FLOW
AT 850MB AND 0-6KM BULK SHEAR VALUES ARE 25-30 KTS AT BEST. THESE
PARAMETERS ARE MARGINALLY SUPPORTIVE OF A FEW STRONG/SEVERE STORMS.
HOWEVER, EXPECT COVERAGE OF STRONG STORMS TO REMAIN LOW GIVEN WEAK
MID/UPPER LEVEL SUPPORT FOR UPWARD ASCENT AND BETTER MOISTURE
CONVERGENCE FOCUSED TO OUR SOUTH. THE BEST CHANCES FOR A FEW STRONG
STORMS CURRENTLY APPEAR TO BE ROUGHLY 22-04Z SOUTH OF US-30 BUT THAT
COULD CHANGE OVER THE NEXT 24-36 HOURS. WILL ALSO HAVE TO KEEP AN
EYE ON THE OVERNIGHT HOURS AS SOME SOLUTIONS SEND AN MCS THROUGH
CENTRAL IL/IN LATE THU NIGHT INTO FRI MORNING THAT COULD CLIP OUR
SOUTHERN ZONES WITH SOME HEAVY RAIN. STILL THINK BETTER CHANCES FOR
THIS WILL BE JUST SOUTH OF OUR AREA ALONG THE MAIN MOISTURE GRADIENT
BUT CONFIDENCE ISN'T HIGH AND WILL WATCH THIS CLOSELY OVER THE NEXT
FEW FORECAST CYCLES.
THE REST OF THE FORECAST IS MAINLY QUIET. A FEW SCT STORMS WILL BE
POSSIBLE AGAIN LATE FRIDAY AND PERHAPS ON SAT. FRIDAY'S CHANCES WILL
BE DEPENDENT ON EXACT TIMING AND EVOLUTION OF POTENTIAL MORNING MCS
BUT SUSPECT A RETURN TO DRY/STABLE NE FLOW BEHIND THIS WAVE WILL
KEEP MOST OF THE AREA DRY FOR MOST OF THIS TIME. AGAIN, BEST CHANCES
FOR A STRAY SHOWER/STORM WILL BE SOUTH OF US-30. NO SEVERE WEATHER
EXPECTED GIVEN EVEN MORE MARGINAL INSTABILITY AND SHEAR PROFILES.
LARGE/STRONG (600+ DAM) MIDLEVEL RIDGE THEN EXPECTED TO DEVELOP OVER
THE CENTRAL CONUS EARLY NEXT WEEK AND LIKELY NOSE INTO OUR REGION AT
SOME POINT. STILL SOME DISAGREEMENT HERE WITH GFS KEEPING THE RIDGE
JUST TO OUR WEST AND ALLOWING A BACKDOOR COLD FRONT MIDWEEK WHILE
ECMWF (AND TO A LESSER EXTENT THE CANADIAN) BULLDOZE THE RIDGE INTO
OUR REGION LEAVING US HOTTER AND DRIER. SLIGHT PREFERENCE FOR THE
LATTER BUT OVERALL NO CHANGES TO THE CONCENSUS INITIALIZATION AT
THIS TIME. /AGD
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 107 PM EDT WED JUL 8 2026
VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. A FEW FAIR
WEATHER CU THIS AFTERNOON AND VERY HIGH CIRRUS. MID LEVEL CLOUDS
WILL START TO INCREASE ON THURSDAY MORNING IN ADVANCE OF THE
NEXT WEATHER SYSTEM. LIGHT SOUTHWEST WINDS WILL ALSO START TO
INCREASE ON THURSDAY, BUT WILL GENERALLY REMAIN AROUND 10 KTS
OR LESS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...AIR QUALITY ALERT UNTIL MIDNIGHT CDT TONIGHT FOR INZ103-203.
OH...NONE.
MI...AIR QUALITY ALERT UNTIL MIDNIGHT EDT TONIGHT FOR MIZ078-177-
277.
MARINE...NONE.
DISCUSSION...HAMMER/AGD
AVIATION...COBB
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