885
FXUS63 KIWX 181856
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
256 PM EDT TUE AUG 18 2026
KEY MESSAGES
- THE NEXT CHANCE OF RAIN ARRIVES TONIGHT AND PERSISTS THROUGH
WEDNESDAY.
- SEVERE WEATHER IS NOT EXPECTED BUT A FEW STRONG STORMS MAY BE
POSSIBLE IN FAR NW IN/SW MI LATE THIS EVENING. HEAVY RAIN IS
ALSO NOT EXPECTED.
- AFTER PLEASANT CONDITIONS THURSDAY AND FRIDAY, MORE LIGHT RAIN
IS EXPECTED ON SATURDAY.
DISCUSSION
ISSUED AT 206 PM EDT TUE AUG 18 2026
NOT A LOT OF WHOLESALE CHANGES TO THIS FORECAST PERIOD. COOL
FRONT CURRENTLY SITTING OVER SOUTHCENTRAL MI AND ORIENTATED TO
THE SOUTHWEST INTO CENTRAL IL STILL ON SCHEDULE TO BEGIN PUSHING
SOUTHEASTWARD INTO THE AREA THIS EVENING. LOOKS LIKE AFTER 6 PM
EDT CHANCES FOR SOME LIGHT SHOWERS INCREASE OUT AHEAD OF THE
INCOMING FRONTAL BOUNDARY FOR OUR FAR NORTHWESTERN PARTS OF THE
CWA BEFORE SOME SCATTERED THUNDERSTORMS ALONG THE FRONT PUSH IN
SHORTLY AFTERWARDS AND CONTINUES TO MOVE SOUTHEASTWARD THROUGH
THE AREA OVERNIGHT INTO WEDNESDAY. FORECASTED INSTABILITY,
MAINLY ELEVATED, WITH VALUES LESS THAN 1000 J/KG COUPLED WITH
DECENT SHEAR VALUES AHEAD OF AND ALONG THE FRONT WITH VALUES
AROUND 70-80 KTS, AND SURFACE DEW POINTS CURRENTLY IN THE 60S
ACROSS THE AREA. EXPECTATION IN THIS ENVIRONMENT WITH THE LATER
DIURNAL TIMING THAT SOME OF THE STORMS MAY BECOME STRONG BUT
WOULD TREND WEAKER THROUGH THE EVENING AS THE FRONT
SOUTHEASTWARD.
ON WEDNESDAY, DEPENDING ON THE EXACT POSITION OF THE FRONTAL
BOUNDARY, WHICH AT THIS TIME WILL MOST LIKELY BE OVER OUR FAR
SOUTH/SOUTHEASTERN PARTS OF THE CWA. WHICH IF THIS DOES PAN OUT
THEN THERE WILL BE AFTERNOON SLIGHT CHANCES OF SHOWERS AND
STORMS MAINLY FOR THE SOUTHERN HALF OF THE CWA WITH THE CLOSE
PROXIMITY OF THE FRONTAL BOUNDARY TO PROVIDE A BIT OF LIFT.
HOWEVER, SEVERE STORMS ARE NOT EXPECTED WITH MOST OF THE AREA TO
THE NORTH OF THE BOUNDARY WITH A LESS THAN IDEAL ENVIRONMENT
ESPECIALLY WITH A DRIER AIRMASS PUSHING IN FROM THE NORTH IN THE
WAKE OF THE FRONT BY WEDNESDAY AFTERNOON AND EVENING. ZONAL FLOW
ALOFT ACROSS THE REGION WILL BRING SLIGHTLY COOLER TEMPERATURES
ACROSS THE AREA INTO FRIDAY WITH HIGHS IN THE UPPER 70S
EXPECTED. FAIRLY NICE WEATHER WITH COMFORTABLE CONDITIONS WILL
BE IN PLACE FOR THURSDAY AND FRIDAY BEFORE ANOTHER COOL FRONT
ASSOCIATED WITH A TROUGH DROPPING SOUTHEASTWARD INTO THE GREAT
LAKES ARRIVES LATE FRIDAY AND INTO SATURDAY INCREASING CHANCES
ONCE AGAIN FOR SHOWERS AND STORMS AND BEFORE PUSHING QUICKLY
EASTWARD.
BY SUNDAY, RIDGING OVER THE CENTRAL CONUS THEN BEGINS TO
BUILD NORTHWARD INTO THE REGION BRINGING ANOTHER PERIOD OF DRY
WEATHER AND A SLIGHT WARMING TREND INTO NEXT WEEK WITH HIGHS
BACK INTO THE LOW 80S.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 128 PM EDT TUE AUG 18 2026
VFR CONDITIONS WITH FAIRLY LIGHT WEST TO SOUTHWEST WINDS ARE
EXPECTED INTO THIS EVENING. A LIKELY WEAKENING AREA OF SHOWERS
AND POSSIBLY A FEW THUNDERSTORMS IS EXPECTED TO MOVE INTO THE
TERMINAL AREA VERY LATE THIS EVENING OR MORE LIKELY JUST AFTER
MIDNIGHT.
IN THE WAKE OF THE RAIN CHANCES, A PERIOD OF LOWER CIGS IS
LOOKING INCREASINGLY POSSIBLE WEDNESDAY MORNING. FOR NOW,
INTRODUCED LOW END MVFR CIGS INTO THE TAFS WITH SOME DIURNAL
IMPROVEMENT EXPECTED BY MID-LATE MORNING. IT IS WORTH NOTING
THAT SOME GUIDANCE DOES BRING CIGS DOWN TO IFR, BUT GIVEN LOW
CONFIDENCE OPTED TO GO QUITE THAT LOW YET.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...ANDERSEN
AVIATION...IZZI
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