152
FXUS63 KIWX 040534
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
134 AM EDT THU SEP 4 2025
KEY MESSAGES
- RAIN ENDING OVERNIGHT.
- ANOTHER STRETCH OF BELOW NORMAL TEMPERATURES THURSDAY THROUGH THIS
WEEKEND.
- THERE IS A HIGH SWIM RISK FOR SOUTHERN LAKE MICHIGAN BEACHES
IN LA PORTE, IN AND BERRIEN COUNTY, MI ON THURSDAY. HAZARDOUS
SWIMMING CONDITIONS PERSIST INTO FRIDAY AND SATURDAY AS WELL.
DISCUSSION
ISSUED AT 207 PM EDT WED SEP 3 2025
A STRONG COLD FRONT, CURRENTLY NEAR THE WI/IL BORDER AND LAKE MI,
WILL SWEEP SOUTHEAST THROUGH THE LOCAL AREA TONIGHT. SCATTERED
PRE-FRONTAL SHOWERS, AND PERHAPS A FEW EMBEDDED THUNDERSTORMS,
WILL REMAIN POSSIBLE THIS AFTERNOON ACROSS MAINLY NW IN AND SW
MI ON THE LEADING EDGE OF THE THETA-E GRADIENT. MORE WIDESPREAD
SHOWER ACTIVITY THEN ACCOMPANIES THE MAIN FRONT FROM NW TO SE
THIS EVENING INTO EARLY THURSDAY AS CVA AND UPPER DIVERGENCE
OVERSPREAD THE FRONTAL SLOPE WITH ADEQUATE MOISTURE TO WORK
WITH. ROBUST POST-FRONTAL COLD ADVECTION THEN BRINGS UNSEASONABLY
COOL WX BACK INTO THE PICTURE TONIGHT INTO THURSDAY. A FEW LAKE
EFFECT SPRINKLES OR SHOWERS CANNOT BE RULED OUT LATER TONIGHT
INTO THURSDAY MORNING IN NW/NC IN AND SW MI AS THIS COLDER AIR
SURGES OVER WARMER LAKE MI WATERS. QUICK DRYING WITH FLOW
TRAJECTORIES BACKING MORE WESTERLY FAVOR LOWER-END POPS (10-
20%). STRATOCU SHOULD SCATTER OUT DURING THE DAY THURSDAY
OTHERWISE WITH HIGHS ONLY REACHING THE MID-UPPER 60S.
THE NEXT SHORTWAVE TROUGH AND ASSOCIATED COLD FRONT WILL TAKE A
SIMILAR PATH AS IT PIVOTS THROUGH THE WESTERN AND SOUTHERN
PERIPHERY OF AN ONTARIO UPPER LOW THROUGH THE UPPER MIDWEST AND
GREAT LAKES. THE BULK OF ANY WARM ADVECTION PRECIPITATION MAINLY
BYPASSES NORTH LATE THURSDAY NIGHT, WITH SHOWER CHANCES APPEARING
LOW ALONG THE TRAILING COLD FRONT ON FRIDAY GIVEN A LESS FAVORABLE
MOISTURE PROFILE AND EXIT OF DEEPER ASCENT. THE MAIN IMPACT WILL BE
THE SOMEWHAT BREEZY CONDITIONS ON FRIDAY WITH THE FROPA AS SFC LOW
PRESSURE EMERGES OVER THE NORTHERN GREAT LAKES, WITH CAA AND
STEEPENING LOW LEVEL LAPSE RATES LIKELY SUPPORTING A FEW GUSTS UP TO
NEAR 25-30 MPH.
HIGH PRESSURE DOMINATES THIS WEEKEND INTO EARLY NEXT WEEK ON THE
BACKSIDE OF THE EXITING LONGWAVE TROUGH WITH COOL WEEKEND TEMPS
(HIGHS MID 60S TO LOW 70S) WARMING BACK UP TO NEAR 80F BY THE MIDDLE
OF NEXT WEEK.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 126 AM EDT THU SEP 4 2025
COLD FRONT HAS CLEARED BOTH LOCATIONS. SOME LINGERING LIGHTER
RAIN/SHOWERS WILL CONTINUE FOR ANOTHER HOUR OR 2 AT KFWA BEFORE
ENDING AS DRIER AIR CONTINUES TO FILTER IN. UPSTREAM OBS AND
SATELLITE IMAGES SHOW RAPID CLEARING OF LOWER CLOUDS TO MOVE
TOWARDS KFWA AFTER 8Z. KSBN A BIT MORE CHALLENGING AS LAKE
EFFECT PARAMETERS INDICATE STRONG SIGNALS FOR A GOOD DEAL OF
INSTABILITY OVERNIGHT INTO THURSDAY MORNING. MOST LIKELY
SCENARIO WILL BE VFR CLOUDS STICK AROUND LONGER UNTIL THE FLOW
BEGINS TO SHIFT LATER TODAY. CAN'T RULE OUT SOME LIGHT SHOWERS
AS WELL, BUT WILL LEAVE THESE OUT FOR NOW.
SOME INCREASED MIXING WILL TAKE PLACES OF STRONGER WIND FIELDS
ALOFT (850 MB WINDS ON THE ORDER OF 30 TO 40 KTS) TO YIELD SOME
GUSTS IN THE 20 TO MAYBE 25 KT RANGE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...BEACH HAZARDS STATEMENT THROUGH THIS AFTERNOON FOR INZ103.
OH...NONE.
MI...BEACH HAZARDS STATEMENT THROUGH THIS AFTERNOON FOR MIZ177-277.
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043-
046.
GALE WATCH FROM LATE TONIGHT THROUGH FRIDAY MORNING FOR LMZ043-
046.
DISCUSSION...STEINWEDEL
AVIATION...FISHER
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