318
FXUS63 KIWX 250558
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
158 AM EDT SAT JUL 25 2026
KEY MESSAGES
- DRY, WARM, AND INCREASINGLY HUMID TODAY.
- HOT AND HUMID WITH HIGHS IN THE UPPER 80S TO LOW 90S BY SUNDAY AND
MONDAY.
- STRONG TO SEVERE STORMS POSSIBLE FROM 8 PM EDT SUNDAY TO 4 AM
EDT MONDAY. DAMAGING WINDS WILL BE THE MAIN THREAT BUT AN
ISOLATED TORNADO OR TWO CANNOT BE RULED OUT.
- ADDITIONAL STRONG TO SEVERE STORMS POSSIBLE MONDAY, ESPECIALLY
IN THE EVENING AND INTO EARLY TUESDAY. LOW CONFIDENCE IN
EXACT TRACK AND TIMING OF STORMS.
DISCUSSION
ISSUED AT 155 AM EDT SAT JUL 25 2026
WINDS WILL BE OUT OF THE SOUTHWEST TODAY AS OUR AREA IS ON THE
BACKSIDE OF AN EXPANSIVE HIGH PRESSURE SYSTEM CENTERED OVER THE
NORTHEASTERN US. AS WAA RAMPS UP THROUGHOUT THE DAY, HIGH
TEMPERATURES WILL BE IN THE UPPER 70S TO LOW 80S WITH A NOTICEABLE
INCREASE IN HUMIDITY COMPARED TO THE PAST FEW DAYS AS DEW POINTS
HOVER AROUND 60 TO 65 DEGREES BY THE AFTERNOON. MID LEVEL
STRATUS CLOUDS ARE EXPECTED TO BUILD IN LATER TODAY. ALSO, SKIES
MAY APPEAR HAZY AT TIMES AS SMOKE FROM ONGOING WILDFIRES IN THE
PACIFIC NORTHWEST DRIFTS IN BUT REMAINS ELEVATED. NO IMPACTS TO
AIR QUALITY OR VISIBILITY ARE EXPECTED. IN COORDINATION WITH
NEIGHBORING OFFICES TO OUR WEST, HAVE TRENDED TEMPERATURES AND
DEW POINTS DOWN A DEGREE OR TWO DUE TO INCREASED CONFIDENCE IN
PARTLY TO MOSTLY CLOUDY SKIES DURING PEAK DIURNAL HEATING.
HOT AND HUMID CONDITIONS ON SUNDAY AND MONDAY WITH POTENTIAL FOR
SEVERE WEATHER. WEST/SOUTHWEST WINDS WILL ADVECT IN HIGHER DEWPOINTS
AROUND 70 TO 75 DEGREES BY SUNDAY AFTERNOON AND AGAIN ON MONDAY.
LOCALLY HIGHER DEWPOINTS WILL BE POSSIBLE DUE TO INCREASED
EVAPOTRANSPIRATION FROM CROPS. CONFIDENCE CONTINUES TO INCREASE IN
THE 'RING OF FIRE' PATTERN SETTING UP WHERE OUR FORECAST AREA WILL
BE ON THE PERIPHERY OF A BUILDING UPPER LEVEL RIDGE CENTERED OVER
THE CENTRAL PLAINS. WITH NORTHWEST STEERING FLOW ALOFT, ONE OR MORE
MCSS COULD DEVELOP AND IMPACT OUR FORECAST AREA LATE SUNDAY THROUGH
EARLY TUESDAY. THE 'RING OF FIRE' PATTERN OFTEN HAS A HIGH CEILING
FOR REPEATED ROUNDS OF SEVERE WEATHER BUT IT IS ALSO HIGHLY
CONDITIONAL. THERE IS A WIDE SPREAD OF SOLUTIONS WITHIN MODEL
GUIDANCE WHICH LENDS ITSELF TO CONSIDERABLE UNCERTAINTY STILL. THE
HOT AND HUMID CONDITIONS WILL FUEL A POTENTIALLY VOLATILE
ENVIRONMENT FOR STORMS WITH UP TO 3000-4000 J/KG SBCAPE AND 40
KTS OF SHEAR. CONVECTIVE INITIATION REMAINS UNCERTAIN AS TO
EXACTLY WHEN AND WHERE IT WILL OCCUR SUNDAY EVENING; THE DAYTIME
HOURS WILL BE MAINLY DRY, WITH THE CHANCES FOR STRONG TO SEVERE
STORMS ANTICIPATED TO INCREASE AFTER 8 PM EDT LASTING THROUGH
ABOUT 4 AM EDT MONDAY. THE GREATEST UNCERTAINTIES AT THIS TIME
ARE THE POTENTIAL FOR CAPPING AND WHAT THE FORCING MECHANISM
WILL BE FOR CONVECTIVE INITIATION. AS MENTIONED IN THE PREVIOUS
DISCUSSION, DETERMINING IF THE CATALYST FOR STORMS WILL BE
UPPER LEVEL VORTICITY MAXIMA, THE UPPER LEVEL JET, OR REMNANT
OUTFLOW BOUNDARIES/MCVS WILL BE VITAL IN UNDERSTANDING WHEN AND
WHERE STORMS WILL TRACK. GIVEN THIS UNCERTAINTY, A BROAD
MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE WEATHER ENCOMPASSES OUR
FORECAST AREA SUNDAY NIGHT. WHAT HAPPENS LATE SUNDAY WILL
INFLUENCE WHAT OCCURS ON MONDAY; HAVE MAINTAINED THE BEST
CHANCES FOR RAIN/STORMS ON MONDAY IN THE EVENING AND EARLY
OVERNIGHT HOURS, ALTHOUGH THIS COULD CHANGE. STORMS ARE EXPECTED
TO GROW UPSCALE INTO A SQUALL LINE OR MATURE MCS, WITH DAMAGING
WINDS AS THE MAIN THREAT. A BRIEF EMBEDDED TORNADO OR TWO WILL
BE POSSIBLE AS WELL AS 0-1 SRH VALUES APPROACH 150-200 M2/S2
SUNDAY NIGHT AND AGAIN ON MONDAY.
EXACTLY HOW HOT AND HUMID IT WILL GET ON MONDAY WILL BE DETERMINED
BY STORMS SUNDAY NIGHT. HAVE MAINTAINED HIGHS IN THE UPPER 80S TO
LOW 90S FOR NOW, BUT DIURNAL HEATING MAY BE DISRUPTED OR STUNTED BY
LINGERING CLOUDS ON MONDAY DEPENDING ON WHAT HAPPENS SUNDAY.
MONDAY'S HEAT INDICES ARE AROUND 100 DEGREES IN THE FORECAST, BUT
WILL HOLD OFF ON HEAT HEADLINES FOR NOW UNTIL BETTER CONFIDENCE
ARISES IN WHAT WILL HAPPEN SUNDAY NIGHT.
TUESDAY AND BEYOND WILL SEE A REPRIEVE IN THE ACTIVE WEATHER PATTERN
AS HIGH PRESSURE BUILDS OVER THE GREAT LAKES. DRY AND SEASONABLE
WITH HIGHS IN THE MID 80S MIDWEEK. AS THE UPPER LEVEL RIDGE BUILDS
AND EXPANDS EASTWARD, HOT AND HUMID CONDITIONS MAY RETURN BY THE END
OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
ISSUED AT 103 AM EDT SAT JUL 25 2026
DRY CONDITIONS AND VFR CEILINGS PREVAIL ON THE BACKSIDE OF A
HIGH PRESSURE SYSTEM TODAY. WINDS WILL BE LIGHT AND VARIABLE
THROUGH THE MORNING, GRADUALLY STRENGTHENING TO AROUND 10 KTS
OUT OF THE SOUTHWEST BY THIS AFTERNOON. ADDITIONAL CLOUDS ADVECT
IN THIS AFTERNOON WITH CEILINGS AROUND 5000 FT. SKIES MAY
APPEAR HAZY AT TIMES AS SMOKE FROM ONGOING WILDFIRES IN THE
PACIFIC NORTHWEST DRIFTS IN BUT REMAINS ELEVATED. NO IMPACTS TO
SURFACE VISIBILITY ARE EXPECTED.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...
AVIATION...JOHNSON
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