981
FXUS63 KIWX 041042
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
642 AM EDT SAT JUL 4 2026
KEY MESSAGES
- HEAT ADVISORY REMAINS IN EFFECT THROUGH EARLY THIS EVENING FOR
MUCH OF NORTHEAST INDIANA AND NORTHWEST OHIO. HEAT INDICES
ARE EXPECTED TOP OUT FROM THE UPPER 90S TO AROUND 100 TODAY.
- SHOWERS AND STORMS WITH A THREAT OF LOCALIZED MINOR FLOODING
WILL COME TO AN END EARLY THIS MORNING. ADDITIONAL
THUNDERSTORMS ARE EXPECTED TO MOVE IN FROM THE WEST THIS
AFTERNOON INTO THIS EVENING. THERE IS A THREAT OF ISOLATED
SEVERE STORMS FROM MID AFTERNOON THROUGH THIS EVENING ACROSS
NORTHERN INDIANA AND NORTHWEST OHIO, WITH THE GREATEST THREAT
GENERALLY SOUTH OF US ROUTE 30 LATE AFTERNOON AND EVENING.
LOCALLY HEAVY RAINFALL WILL ALSO BE POSSIBLE AGAIN.
- SCATTERED THUNDERSTORM POTENTIAL CONTINUES INTO SUNDAY, A FEW
OF THESE MAY PRODUCE GUSTY WINDS BUT SEVERE STORMS ARE NOT
EXPECTED AT THIS TIME. A TREND TO DRIER CONDITIONS IS THEN
EXPECTED FOR EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 345 AM EDT SAT JUL 4 2026
THE MAIN FORECAST CONCERNS WILL BE ON CONVECTIVE POTENTIAL THROUGH
SUNDAY AND ALSO LINGERING HEAT ISSUES TODAY.
A CONVECTIVE COMPLEX CONTINUES TO TRACK ACROSS NORTHERN INDIANA
AND NORTHWEST OHIO THIS MORNING. THE OVERALL TREND HAS BEEN A
WEAKENING ONE AS SOME WEAK MIXED LAYER CIN APPEARS TO BE
DEVELOPING. THESE STORMS HAVE LATCHED ONTO A FAIRLY STRONG
GRADIENT OF MLCAPE ACROSS NORTHERN INDIANA, WITH THE MAGNITUDE
OF THIS INSTABILITY AXIS GRADUALLY WANING THROUGH TIME. STORMS
IN THIS COMPLEX HAVE EXHIBITED BOTH FORWARD AND UPWIND
PROPAGATION DUE TO OUTFLOW HELPING TO GENERATE NEW CELLS INTO
THE BETTER MLCAPE AXIS. THIS DUAL PROPAGATION MODE HAS BEEN
EFFICIENT IN TRAINING OF STORMS WITH SOME LOCALIZED VERY HEAVY
RAINFALL OVERNIGHT ACROSS PORTIONS OF SOUTHWEST LOWER MICHIGAN
AND INTO PORTIONS OF MARSHALL COUNTY, KOSCIUSKO COUNTY, AND
SOUTHWEST ELKHART COUNTY IN NORTHERN INDIANA. SOME LOCALIZED
PONDING ISSUES COULD CONTINUE DOWNSTREAM WITH THIS DECAYING
COMPLEX OVER THE NEXT FEW HOURS ALONG WITH A FEW INSTANCES OF
40+ MPH GUSTS AND PEA SIZED HAIL ACROSS SOUTHEAST PORTIONS OF
THE AREA. TRAILING AREA OF SHOWERS WITH A FEW EMBEDDED STORMS ACROSS
EAST CENTRAL ILLINOIS MAY DRIFT NORTHEAST INTO AREAS THAT
EXPERIENCED THE HEAVY RAINFALL OVERNIGHT ACROSS NORTHERN
INDIANA, AND THIS MAY NECESSITATE SOME ADDITIONAL HYDRO
HEADLINES THIS MORNING ACROSS THESE AREAS.
THIS MORNING'S ACTIVITY SHOULD SUPPRESS COMPOSITE OUTFLOW
BOUNDARY WITH SOME UNCERTAINTY THIS AFTERNOON IN TERMS OF EXACT
POSITIONING/MOVEMENT OF MAIN OUTFLOW BOUNDARY. AS WAS THE CASE
YESTERDAY WILL ALSO NEED TO MONITOR SPEED/STRENGTH OF A LIKELY
ADDITIONAL CONVECTIVELY ENHANCED SHORT WAVE KICKING OUT OF
REMNANTS OF LARGER CONVECTIVE COMPLEX ACROSS IA/NORTHERN MO. THE
APPROACH OF THIS SHORT WAVE COULD ALLOW THE COMPOSITE OUTFLOW
BOUNDARY TO START TO RETREAT NORTHWARD A BIT THIS AFTERNOON.
CAMS OFFER A WIDE RANGE OF SOLUTIONS AGAIN, BUT OVERALL
CONSENSUS SEEMS TO BE FOR A SLIGHTLY SUPPRESSED MLCAPE GRADIENT
IN COMPARISON TO YESTERDAY AND OF A BIT LESS MAGNITUDE. SHEAR
PROFILES SHOULD ALSO BE MARGINAL AGAIN, ALTHOUGH WILL NEED TO
WATCH IF ANY POCKETS OF STRONGER SHEAR EMERGE ACROSS CENTRAL IL
THIS AFTERNOON FROM AFOREMENTIONED UPSTREAM CONVECTION THAT
COULD SPILL INTO WESTERN IN TOWARD EVENING. SWODY1 KEEPS
NORTHERN INDIANA/NORTHWEST OHIO IN A WIND DAY 1 MARGINAL RISK
FOR SEVERE STORMS, WITH PERHAPS GREATEST ISOLATED RISK SOUTH OF
US 30 WHICH MIGHT REPRESENT BEST INSTABILITY AND POTENTIAL
INTERACTION OF INCOMING SMALLER SCALE WAVE WITH SOME REMNANT
OUTFLOW BOUNDARY INFLUENCE. LOCALIZED DAMAGING WIND GUSTS APPEAR
TO BE THE PRIMARY THREAT ONCE AGAIN FROM THE MID AFTERNOON INTO
EVENING TIME FRAME (PERHAPS GREATEST THREAT IN THE EARLY
EVENING HOURS).
HAVE NOT MADE ANY CHANGES TO THE PREVIOUS HEAT HEADLINES AT THIS
TIME. IT DOES APPEAR WITH DECAYING CONVECTION THIS MORNING, THERE
SHOULD BE TIME FOR TEMPS TO RECOVER ENOUGH THAT MID 90S TO AROUND
100 HEAT INDICES ARE POSSIBLE AGAIN FOR THE HEAT ADVISORY AREA.
FOR SUNDAY A WEAK UPPER JET STREAK IS PROGGED TO DIVE SOUTHEAST IN
UPPER LEVEL DIFFLUENT FLOW ACROSS THE NORTHERN PLAINS AND MAY
TEND TO PHASE WITH REMNANTS OF THE SATURDAY NIGHT SHORT WAVE
TROUGH. THIS FEATURE WILL BE SLOW TO SHIFT EASTWARD INTO EARLY
MONDAY. CONVECTIVE EVOLUTION IS OF VERY LOW CONFIDENCE FOR
SUNDAY WITH A CONTINUED WEAK SHEAR/MODERATE CAPE SETUP POSSIBLE.
COLUMN MOISTURE SHOULD STILL BE QUITE IMPRESSIVE, BUT OVERALL
WEAKLY FORCED NATURE OF THIS SETUP AND WEAK KINEMATIC PROFILES
SHOULD LIMIT OVERALL SEVERE THREAT. CANNOT RULE OUT A LOCALIZED
HEAVY RAIN PRODUCER SUNDAY GIVEN WHAT SHOULD BE FAIRLY SLOW
STORM MOTIONS IF STORMS CAN DEVELOP, ALONG WITH A VERY LOW
PROBABILITY OF A PRECIP LOADED GUSTY STORM. WHATEVER OUTFLOW
BOUNDARIES ARE LEFTOVER FROM SATURDAY NIGHT AND EXACTLY WHERE
SFC REFLECTION OF THIS MID/UPPER LEVEL TROUGHING PATTERN SETS UP
ARE ITEMS OF LOWER CONFIDENCE THAT WILL INFLUENCE CONVECTIVE
FORECAST FOR SUNDAY.
THE TREND TO A QUIETER PATTERN EARLY NEXT WEEK STILL LOOKS
INTACT AS POSITIVE MID/UPPER LEVEL HEIGHT TENDENCIES BUILD IN
BEHIND SLOWLY EASTWARD MIGRATING NEGATIVE UPPER HEIGHT ANOMALY
ACROSS THE OHIO VALLEY/SOUTHERN GREAT LAKES. PROXIMITY OF THE
UPPER LEVEL TROUGH COULD STILL PROVIDE SOME DIURNALLY ENHANCED
SCATTERED SHOWERS AND STORMS ON MONDAY, PARTICULARLY EAST OF
I-69 CORRIDOR. THIS INCOMING RIDGE MAY BE DAMPENED BY THE LATE
WED/THU PERIOD AS MORE ACTIVE NORTHERN STREAM TAKES SHAPE. SOME
LEADING RETURN POSITIVE LOW LEVEL THETA-E ADVECTION AND SOME
ADDITIONAL FRONTAL FORCING COULD ALLOW FOR RENEWED SHOWER/STORM
CHANCES FOR MIDDLE AND LATTER PORTIONS OF THE UPCOMING WORK
WEEK.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 632 AM EDT SAT JUL 4 2026
COMPOSITE OUTFLOW AND PROXIMITY OF SFC BOUNDARY DROPPING ACROSS
THE SOUTHERN GREAT LAKES HAS PROVIDED SOME IFR CONDITIONS TO
KSBN. THIS IFR CIGS APPEAR TO BE SHORT-LIVED WITH LOW
PROBABILITIES THAT THEY WILL LAST PAST 12Z THIS MORNING.
OTHERWISE, ELEVATED SHOWERS WITH A FEW STORMS PERSIST THIS
MORNING WELL NORTH OF AN OUTFLOW BOUNDARY THAT HAS DROPPED
SOUTH ACROSS NORTHERN INDIANA. MUCH LIKE YESTERDAY, WILL NEED TO
WATCH THE POTENTIAL OF ANOTHER CONVECTIVELY ENHANCED SHORT WAVE
COMING OUT OF DECAYING CONVECTION ACROSS N MO/IA WITH SOME
ISENTROPIC FORCING POSSIBLE DOWNSTREAM OF THIS WAVE AS IT
POTENTIALLY INTERACTS WITH SYNOPTIC AND/OR OUTFLOW BOUNDARIES.
BEST CHANCE OF THUNDER REDEVELOPMENT TODAY APPEARS TO BE AFTER
19Z AT KSBN, AND AFTER 21 OR 22Z AT KFWA. GIVEN INFLUENCE OF
THIS OUTFLOW BOUNDARY, INSTABILITY FIELDS WILL LIKELY BE A BIT
LESS THAN YESTERDAY AND SUPPRESSED A BIT TO THE SOUTH. GIVEN
DEPENDENCE OF MESOSCALE DETAILS ONCE AGAIN, DID NOT HAVE ENOUGH
CONFIDENCE TO GO MORE THAN PROB30 TSRA MENTION THIS AFTERNOON.
SOME MVFR VSBYS/CIGS ARE POSSIBLE LATE IN THIS PERIOD AS
SYNOPTIC BOUNDARY BEGINS TO DROP SOUTH AND DUE TO INFLUENCE OF
LIKELY OUTFLOW BOUNDARY PASSAGE/MOIST LOW LEVELS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR INZ009-017-018-
022>027-032>034.
OH...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR OHZ001-002-004-
005-015-016-024-025.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...MARSILI
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