570  
FXUS63 KIWX 011853  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
253 PM EDT MON SEP 1 2025  
   
KEY MESSAGES
 
 
- LARGE DIURNAL SWINGS (DAILY TEMPERATURE RANGES) ARE EXPECTED  
THROUGH WEDNESDAY WITH HIGHS NEAR 80 AND LOWS WELL DOWN INTO  
THE 50S.  
 
- A STRONG COLD FRONT WILL BRING SHOWERS AND ISOLATED THUNDERSTORMS  
WEDNESDAY AFTERNOON THROUGH EARLY THURSDAY,  
 
- HIGHS ONLY IN THE 60S THURSDAY AND FRIDAY WITH CHILLY LOWS WELL  
DOWN INTO THE 40S.  
 
- THERE IS A HIGH SWIM RISK FOR BOTH LA PORTE COUNTY, IN AND  
BERRIEN COUNTY, MI ON THURSDAY.  
 

 
   
DISCUSSION
 
 
ISSUED AT 229 PM EDT MON SEP 1 2025  
 
COOL AND DRY WEATHER PERSISTED OVER A LARGE PART OF THE REGION  
ASSOCIATED WITH AN EXPANSIVE HIGH PRESSURE RIDGE FROM NEW ENGLAND TO  
THE HIGH PLAINS. THE AIRMASS WILL ATTEMPT TO MODIFY AHEAD OF A COLD  
FRONT THAT IS EXPECTED TO ARRIVE THURSDAY NIGHT. THE LATEST MODEL  
RUNS SUPPORT CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS IN  
ABOUT A 24 HOUR WINDOW FROM WEDNESDAY 18Z (2PM EDT) TO THURSDAY  
18Z (2 PM EDT) WITH THE PASSAGE OF THE FRONT. AHEAD OF THIS FRONT,  
LARGE DIURNAL TEMPERATURE RANGES WILL PERSIST WITH HIGHS AROUND  
80 AND LOWS FROM 50 TO 55.  
 
SHOWERS AND ISOLATED STORMS ARE EXPECTED WITH THE PASSAGE OF THE  
FRONT LATE WEDNESDAY AND WEDNESDAY NIGHT. SEVERE STORMS ARE NOT  
FORECAST GIVEN VERY LIMITED MOISTURE AND INSTABILITY, AND  
OVERALL RELATIVELY WEAK AND LIMITED DYNAMICS. MAINLY DRY AND  
COOL WEATHER IS AHEAD FROM LATE THURSDAY THROUGH THE WEEKEND  
WITH HIGHS IN THE UPPER 60S TO LOWER 70S.  
 

 
   
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
 
 
ISSUED AT 1252 PM EDT MON SEP 1 2025  
 
REX BLOCK PATTERN CONTINUES A FORECAST PERSISTENCE MODE WITH THE 18Z  
TAFS. AN EXPANSIVE LOW LEVEL ANTICYCLONE TIED TO A BROAD NORTHERN  
STREAM UPPER RIDGE WILL CONTINUE TO ALLOW A WEAK EASTERLY FLOW  
REGIME TO PERSIST ACROSS NORTHERN INDIANA. WITH A FEW DEGREES OF  
WARMING TODAY COMPARED TO YESTERDAY, SOME POTENTIAL EXISTS FOR A  
WEAK LAKE BREEZE TO IMPACT KSBN LATE IN THE AFTERNOON OR EARLY  
EVENING WITH A BRIEF PERIOD OF NORTHEAST WINDS LESS THAN 10 KNOTS  
POSSIBLE. SOME PATCHY SHALLOW FOG IS ALSO POSSIBLE EARLY TUESDAY  
MORNING, BUT EXPECTATION IS THAT THIS WOULD BE MAINLY FOR OUTLYING  
RURAL LOCATIONS AND WILL CONTINUE TO OMIT MENTION FROM TERMINAL  
FORECAST.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...NONE.  
 

 
 

 
 
DISCUSSION...SKIPPER  
AVIATION...MARSILI  
 
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