584
FXUS63 KIWX 252254
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
654 PM EDT TUE AUG 25 2026
KEY MESSAGES
- SEASONABLE TEMPERATURES, DRY CONDITIONS, AND MUCH LOWER
HUMIDITY CONTINUE TODAY.
- THERE IS A SLIGHT RISK FOR SEVERE WEATHER WITH ALL HAZARDS POSSIBLE
ON WEDNESDAY. SCATTERED SEVERE STORMS ARE MOST LIKELY BETWEEN
4 TO 11 PM EDT.
- DRY AND SLIGHTLY WARMER THURSDAY THROUGH THE WEEKEND AHEAD.
DISCUSSION
ISSUED AT 110 PM EDT TUE AUG 25 2026
WITH HIGH PRESSURE SITUATED OVERHEAD AGAIN TODAY, ANOTHER TRANQUIL
DAY IS EXPECTED WITH MILD AND DRY CONDITIONS. NEAR NORMAL
TEMPERATURES ARE EXPECTED TODAY WITH HIGHS IN THE UPPER 70S TO LOW
80S AS THE AIRMASS OVERHEAD MODERATES AND LIGHT SOUTHWEST WINDS
PERSIST. COMFORTABLE HUMIDITY WITH DEW POINTS IN THE MID TO UPPER
50S CONTINUES TODAY TOO.
BECOMING INCREASINGLY WARMER AND HUMID WEDNESDAY WITH 40-70% CHANCES
FOR RAIN AND STORMS, ESPECIALLY BY THE AFTERNOON AND EVENING.
SCATTERED SEVERE WEATHER WILL BE POSSIBLE AS SPC MAINTAINS A SLIGHT
RISK (LEVEL 2 OF 5) FOR OUR ENTIRE FORECAST AREA. AN UPPER LEVEL LOW
WILL DEEPEN OVER THE HUDSON BAY AND AN ATTENDANT SURFACE COLD FRONT
IS EXPECTED TO MOVE THROUGH DURING THE AFTERNOON AND EVENING.
SCATTERED YET SHORT-LIVED LIGHT SHOWERS MAY OCCUR IN THE MORNING
AROUND DAYBREAK WITH A LEADING WEAK SHORTWAVE, BUT THEY QUICKLY
DIMINISH. AT LEAST PARTIAL CLEARING SHOULD COMMENCE BY THE MORNING
INTO THE EARLY AFTERNOON, ALLOWING FOR THE AIRMASS OVERHEAD TO
DESTABILIZE WITH INCREASED WAA AND LOW LEVEL MOISTURE TRANSPORT FROM
VEERING SOUTHERLY WINDS. ISOLATED DISCRETE STORMS COULD DEVELOP AS
EARLY AS 1-2 PM EDT IN OUR FAR NORTHWEST NEAR LAKE MICHIGAN
(ESPECIALLY IF THERE IS A LAKE BREEZE TO ENHANCE LIFT), BUT STILL
THINKING THE BEST CHANCES FOR STRONG TO SEVERE STORMS HOLD OFF UNTIL
3-4 PM EDT AND LATER AS THE FRONT MOVES EAST-SOUTHEAST. GIVEN THE
FAVORABLE DIURNAL TIMING, HIGHS IN THE LOW 80S, AND DEWPOINTS IN THE
UPPER 60S TO NEAR 70, SEVERE WEATHER IS POSSIBLE AS UP TO 2500 J/KG
OF SURFACE BASED INSTABILITY AND DECENT 0-6 KM SHEAR OF ~30 KTS
SHOULD DEVELOP WEDNESDAY AFTERNOON AND EVENING AHEAD OF THE FRONT.
THERE IS STILL SOME UNCERTAINTY TO WORK OUT AS TO WHAT EXACTLY THE
STORM MODE WILL BE; IT IS POSSIBLE THAT DISCRETE SUPERCELLS DEVELOP
INITIALLY BEFORE GROWING UPSCALE INTO MULTICELL/LINEAR SEGMENTS. ALL
HAZARDS WILL BE POSSIBLE INCLUDING DAMAGING WIND GUSTS TO 60 MPH,
QUARTER SIZE HAIL, AND A FEW TORNADOES. IT IS WORTH NOTING THAT SPC
HAS A 5% TORNADO PROBABILITY FOR NORTHERN INDIANA AND FAR SOUTHERN
LOWER MICHIGAN WHEN SPIN IS MAXIMIZED CLOSEST TO THE SURFACE COLD
FRONT. LOW LEVEL PROFILES ON FORECAST SOUNDINGS DO APPEAR FAVORABLE
FOR TORNADOES WITH 100-150 M2/S2 0-1 SRH AND LCLS OF 750M,
ESPECIALLY IF DISCRETE SUPERCELLS END UP BEING THE PRIMARY STORM
MODE. THE ONLY INGREDIENT THAT IS LACKING IS THE LOW AND MID LEVEL
LAPSE RATES. IF LAPSE RATES OF ONLY 6 TO 6.5 C/KM OCCUR TOMORROW,
THIS MAY BE A POSSIBLE FAILURE MODE AND/OR LIMITING FACTOR FOR
CONVECTION.
ANOTHER AREA OF HIGH PRESSURE BUILDS ACROSS THE MIDWEST AND GREAT
LAKES LATE IN THE WEEK, BRINGING A RETURN TO DRY CONDITIONS THURSDAY
THROUGH SUNDAY. HAVE KEPT LOW CHANCES (20-30%) FOR RAIN AND STORMS
FOR MONDAY. TEMPERATURES WILL REMAIN NEAR NORMAL WITH A GRADUAL
WARMING TREND INTO THE MID 80S FOR HIGHS BY THE WEEKEND INTO EARLY
NEXT WEEK.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 651 PM EDT TUE AUG 25 2026
HIGH PRESSURE REMAINS IN PLACE FOR A MAJORITY OF THIS TAF
PERIOD, CENTERED OVER FAR SOUTH-CENTRAL MI. A COLD FRONT WORKING
ITS WAY THROUGH WESTERN IOWA AT THIS TIME WILL BE OF INTEREST
WEDNESDAY AFTERNOON AS ISOLATED TO SCATTERED TO THUNDERSTORMS
DEVELOP AHEAD OF IT. TIMING OFFERS MEDIUM CONFIDENCE AND
LIKELY EXTENDS BEYOND THE 00Z CUT-OFF AT KFWA.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...BROWN
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