454
FXUS63 KIWX 242327
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
727 PM EDT MON AUG 24 2026
KEY MESSAGES
- SEASONABLE TEMPERATURES, DRY CONDITIONS, AND MUCH LOWER HUMIDITY
CONTINUE THROUGH TUESDAY.
- 40-60% CHANCES FOR RAIN AND STORMS WEDNESDAY AFTERNOON AND
EVENING. THERE IS A MARGINAL RISK FOR SEVERE WEATHER WITH ALL
HAZARDS POSSIBLE. LOW CONFIDENCE.
DISCUSSION
ISSUED AT 102 PM EDT MON AUG 24 2026
HIGH PRESSURE DIRECTLY OVERHEAD IS MAKING FOR A VERY TRANQUIL AND
PLEASANT LATE AUGUST DAY! HIGHS ARE EXPECTED TO REACH THE UPPER 70S
TODAY AMID MOSTLY SUNNY SKIES WITH LIGHT NORTHWEST WINDS. PARTLY
CLOUDY SKIES OVERNIGHT SHOULD KEEP ANY FOG CONCERNS AT BAY AS
RADIATIONAL COOLING SHOULD BE SOMEWHAT LIMITED, ALTHOUGH LOWS ARE
EXPECTED TO BE IN THE LOW TO MID 50S AGAIN TUESDAY MORNING.
WITH HIGH PRESSURE SITUATED OVER THE GREAT LAKES REGION AGAIN
TOMORROW, HIGHS WILL BE SLIGHTLY WARMER IN THE UPPER 70S TO LOW 80S
AS THE AIRMASS OVERHEAD MODERATES AND WINDS SHIFT TO BE OUT OF THE
SOUTHWEST. COMFORTABLE HUMIDITY WITH DEW POINTS IN THE MID TO UPPER
50S CONTINUES THROUGH TUESDAY.
WEDNESDAY IS INCREASINGLY WARMER AND HUMID WITH 40-60% CHANCES FOR
RAIN AND STORMS. AN UPPER LEVEL TROUGH WILL DEEPEN OVER THE GREAT
LAKES AND A SURFACE COLD FRONT IS EXPECTED TO MOVE THROUGH DURING
THE DAY. OUR AREA WILL BE IN THE WARM SECTOR OUT AHEAD OF THE FRONT
WITH INCREASED WAA AND LOW LEVEL MOISTURE TRANSPORT FROM SOUTHERLY
WINDS. GIVEN THE FAVORABLE TIMEFRAME, HIGHS IN THE LOW 80S, AND
DEWPOINTS IN THE UPPER 60S TO NEAR 70, SEVERE WEATHER IS POSSIBLE AS
1500-2500 J/KG OF SURFACE BASED INSTABILITY AND DECENT 0-6 KM SHEAR
OF 25-30 KTS SHOULD DEVELOP WEDNESDAY AFTERNOON AND EVENING. WITH
THE FRONTAL PASSAGE DURING THE PEAK HEATING HOURS OF THE DAY, AT
LEAST ISOLATED SEVERE WEATHER WILL BE POSSIBLE AS SPC MAINTAINS A
MARGINAL RISK (LEVEL 1 OF 5) FOR WEDNESDAY. 60 MPH WIND GUSTS AND 1"
HAIL WILL BE THE MAIN THREATS WITH MULTICELLULAR CLUSTERS THAT ARE
EXPECTED TO DEVELOP BUT IF A FEW DISCRETE STORMS CAN MAINTAIN
THEMSELVES (LOW CONFIDENCE), AN ALL HAZARDS SETUP MAY OCCUR.
FORECAST SOUNDINGS FROM THE NAM, RAP, AND GFS SHOW VARYING
AMOUNTS OF LOW LEVEL SHEAR AND HELICITY, SO THERE ARE STILL SOME
UNCERTAINTIES TO SORT THROUGH. IN THE VICINITY OF THE COLD
FRONT, 100-150 M2/S2 OF SRH WHICH WOULD PROVIDE ENOUGH SPIN TO
SUPPORT AN ISOLATED TORNADO THREAT. ALL OF THE MODELS HAVE POOR
LAPSE MID AND LOW LEVEL LAPSE RATES THOUGH, WHICH COULD INDICATE
THIS BEING A A LIMITING FACTOR AND/OR A POSSIBLE FAILURE MODE.
THERE IS STILL UNCERTAINTY REGARDING EXACT TIMING, COVERAGE, AND
INTENSITY OF STORMS.
ANOTHER AREA OF HIGH PRESSURE BUILDS ACROSS THE MIDWEST AND GREAT
LAKES LATE IN THE WEEK, BRINGING A RETURN TO DRY CONDITIONS AT LEAST
THROUGH THE FIRST HALF OF THE UPCOMING WEEKEND. HAVE KEPT LOW
CHANCES (20-30%) FOR RAIN AND STORMS FOR SUNDAY. TEMPERATURES WILL
REMAIN NEAR NORMAL WITH A GRADUAL WARMING TREND INTO THE MID 80S FOR
HIGHS BY THE END OF AUGUST.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 727 PM EDT MON AUG 24 2026
HIGH PRESSURE PARKED OVERHEAD YIELDS CALM WIND DURING THE
OVERNIGHT HOURS. RADIATION FOG APPEARS A STRONG POSSIBILITY.
HOWEVER, INCOMING MID-LEVEL CLOUDS FROM WI ARE ONE ELEMENT THAT
DECREASES FORECAST CONFIDENCE, THOUGH THESE CLOUDS MAY MOVE ON
WITH PLENTY OF TIME FOR RADIATION FOG TO DEVELOP. GIVEN THE
INHERITED TAF MENTION AND AN OVERALL FAVORABLE SYNOPTIC SETUP,
I'VE INCLUDED TEMPO IFR CONDITIONS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...BROWN
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