304
FXUS63 KIWX 040533
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
133 AM EDT SAT JUL 4 2026
KEY MESSAGES
- A NEW HEAT ADVISORY HAS BEEN ISSUED FOR AREAS MAINLY EAST OF
I-69 AND SOUTH OF US 24 THROUGH 8 PM EDT SATURDAY. PEAK HEAT
INDICES SATURDAY AFTERNOON ARE EXPECTED TO BE AROUND 100
DEGREES.
- SHOWERS AND THUNDERSTORMS WILL CONTINUE TONIGHT AND WILL
GRADUALLY DIMINISH IN COVERAGE LATE IN THE OVERNIGHT.
LOCALIZED WIND GUSTS IN EXCESS OF 40 MPH AND LOCALIZED
FLOODING WILL BE THE MAIN THREATS OVERNIGHT.
- HOT AND HUMID FOR THE 4TH OF JULY WITH 30-50% CHANCES FOR
SHOWERS AND STORMS. THERE IS A MARGINAL RISK (LEVEL 1 OF 5)
FOR SEVERE WEATHER. CONFIDENCE IS LOW BUT ISOLATED SEVERE
STORMS WILL BE POSSIBLE BETWEEN 2-11 PM EDT WITH DAMAGING WIND
GUSTS, HEAVY RAIN, AND LIGHTNING AS THE MAIN THREATS.
DISCUSSION
ISSUED AT 141 PM EDT FRI JUL 3 2026
HIGH HEAT AND HUMIDITY IS EXPECTED TO SUSTAIN SCATTERED STORMS LATER
THIS EVENING. A GROWING CUMULUS FIELD IS EVIDENT ON VISIBLE
SATELLITE IMAGERY WITH STRONG TO SEVERE STORMS SEEN ON RADAR ACROSS
PARTS OF SOUTHERN WISCONSIN AND NORTHERN ILLINOIS. HOW MUCH THE
STORMS MAINTAIN THEIR STRENGTH IS UNCERTAIN BUT THE HOT AND HUMID
AIRMASS OVERHEAD HAD LED TO AN IMPRESSIVE 3000-4000 J/KG OF SBCAPE
THIS AFTERNOON ALREADY. LATEST ITERATIONS OF THE HRRR SHOW A FEW
ISOLATED STORMS MAY DEVELOP ACROSS SOUTHWEST LOWER MICHIGAN AND
NORTHWEST INDIANA BETWEEN 21-00Z THIS EVENING, WITH ADDITIONAL
STORMS BUILDING IN BETWEEN 03-06Z MAINLY NORTH OF US-30 ALONG
OUTFLOW BOUNDARIES LEFTOVER FROM THE IL/WI CONVECTION. SPC HAS
MAINTAINED THE SLIGHT RISK (LEVEL 2 OF 5) FOR OUR FORECAST AREA.
MULTICELL STORM CLUSTERS ARE EXPECTED TO POSE A DAMAGING WIND THREAT
THIS EVENING INTO TONIGHT. FORECAST SOUNDINGS DEPICT INVERTED V
PROFILES WITH DCAPE ABOVE 1000 J/KG, WHICH ALSO INDICATES A
FAVORABLE ENVIRONMENT FOR MICROBURSTS. OTHER FAVORABLE PARAMETERS
INCLUDE LOW LEVEL LAPSE RATES IN EXCESS OF 8 C/KM AND PWATS AROUND
1.5". IN ADDITION TO THE DAMAGING WIND THREAT, HEAVY RAINFALL AND
LIGHTNING WILL BE HAZARDS AS WELL.
AS THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN,GIVEN A LOW SHEAR
ENVIRONMENT AND POTENTIAL FOR LEFTOVER OUTFLOW BOUNDARIES IN THE
AREA, HAVE CONTINUED TO MAINTAIN DAILY PERIODIC CHANCES FOR STORMS
THROUGH THE HOLIDAY WEEKEND. HOW THE PATTERN EVOLVES IS DEPENDENT ON
MESOSCALE AND EVEN SOME STORM SCALE PARAMETERS, WHICH MAKES
FORECASTING BEYOND JUST 6 TO 12 HOURS AHEAD OF TIME VERY TRICKY AND
UNCERTAIN. WHILE THERE IS MEDIUM CONFIDENCE ON TODAY'S SETUP,
EVERYTHING BEYOND THIS EVENING IS MURKY AND LOW CONFIDENCE IN EXACT
TIMING AND LOCATION OF STORMS.
JULY 4TH WILL NOT BE A COMPLETE WASHOUT, HOWEVER, THERE IS STILL A
MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE WEATHER. SATURDAY MARKS THE
BEGINNING OF OUR SLIGHT COOL DOWN, WITH HIGHS IN THE MID 80S TO NEAR
90 DEGREES. HUMID CONDITIONS STICK AROUND FOR THE HOLIDAY THOUGH
WITH DEWPOINTS IN THE LOW TO MID 70S. A HEAT ADVISORY HAS BEEN
ISSUED FOR OUR SOUTHEAST HALF, INCLUDING FROM CASS COUNTY, IN UP TO
WHITLEY COUNTY, IN UP TO WILLIAMS COUNTY, OH UNTIL 8 PM EDT SATURDAY
WHERE PEAK HEAT INDICES WILL BE AROUND 100 DEGREES. IN ADDITION TO
THE CONTINUED HEAT AND HUMIDITY, THIS MODERATELY UNSTABLE AIRMASS
SHOULD AID IN AT LEAST ISOLATED THUNDERSTORM DEVELOPMENT BETWEEN 2-
11 PM EDT SATURDAY. THIS SETUP WILL BE HIGHLY DEPENDENT ON MORNING
CONVECTION, LEFTOVER CLOUD DEBRIS, AND IF/WHERE THERE ARE ANY OLD
OUTFLOW BOUNDARIES IN THE AREA. IT'S POSSIBLE, DEPENDING ON WHERE
REMNANT OUTFLOW BOUNDARIES DISPERSE, THAT STORMS END UP MAINLY ALONG
AND SOUTH OF US 30. WITH A SIMILAR ENVIRONMENT TO TODAY,ISOLATED
DAMAGING WIND GUSTS WOULD BE THE MAIN THREAT AGAIN SATURDAY IN
ANY STRONG TO SEVERE STORMS; EVEN IF STORMS STAY SUB-SEVERE,
HEAVY RAIN AND LIGHTNING WILL STILL BE HAZARDS. IF YOU HAVE ANY
OUTDOOR PLANS FOR THE 4TH OF JULY, STAY SAFE AND STAY COOL!
A TROUGH EJECTING OUT OF THE WESTERN US COULD BRING ADDITIONAL
CHANCES FOR SHOWERS AND STORMS ON SUNDAY. THE EARLY TO MIDDLE PART
OF NEXT WEEK LOOKS MOSTLY DRY AS A HIGH PRESSURE SYSTEM SETS UP OVER
THE MIDWEST AND GREAT LAKES. WHILE IT MAY BE SLIGHTLY 'COOLER' INTO
EARLY NEXT WEEK WITH HIGHS IN THE 80S, THE LONG TERM PATTERN
CONTINUES TO FAVOR ABOVE NORMAL TEMPERATURES THROUGH MID JULY.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 1243 AM EDT SAT JUL 4 2026
ANOTHER CONVECTIVE COMPLEX SHIFTING EAST OUT OF NORTHERN
ILLINOIS IS STARTING TO SHOW SIGNS OF MORE OUTFLOW DOMINANCE
OVER THE PAST HOUR OR TWO. ADDITIONAL SCATTERED STORMS HAVE
DEVELOPED AHEAD OF THE SOUTHEAST SURGING OUTFLOW AND ARE LIKELY
AUGMENTING THESE STORMS. WILL LIKELY INCLUDE TEMPO TSRA GROUP IN
THE 06 TO 10Z PERIOD FOR THE TERMINALS WITH EVENTUALLY DECAY OF
THIS COMPLEX IN NEXT 2 TO 4 HOURS WITH OUTFLOW DOMINANCE AND
EVENTUAL WANING OF SOUTHEAST SAGGING MLCAPE AXIS. AN ADDITIONAL
CONVECTIVELY ENHANCED SHORT WAVE IS EXPECTED TO APPRAOCH FROM
PORTIONS OF CENTRAL IL/NORTHWEST IN ON SATURDAY AND WILL LIKELY
RESULT IN ADDITIONAL SCATTERED STORMS TO DEVELOP. CURRENT
INDICATIONS WOULD SUGGEST FAVORED INSTABILITY GRADIENT A BIT
MORE SUPPRESSED THEN TODAY, WITH KFWA STANDING BEST CHANCE OF
MORE AFTERNOON STORMS ON SATURDAY. WITH STILL A GOOD DEAL OF
UNCERTAINTY GIVEN CONVECTIVE AUGMENTATION OF SHORT WAVES AND
OUTFLOW BOUNDARY INFLUENCE, WILL LIMIT THIS MENTION TO PROB30 AT
KFWA FOR SATURDAY AFTERNOON. VFR CONDITIONS ARE EXPECTED THIS
PERIOD, WITH THE EXCEPTION OF BRIEF MVFR OR IFR RESTRICTIONS IN
HEAVIER SHOWERS/STORMS.
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...JOHNSON
AVIATION...MARSILI
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