558  
FXUS63 KIWX 181657  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
1257 PM EDT TUE SEP 18 2018  
   
SYNOPSIS
 
 
ISSUED AT 332 AM EDT TUE SEP 18 2018  
 
WARM CONDITIONS CAN BE EXPECTED THIS WEEK. HIGHS WILL GENERALLY  
BE IN THE LOWER TO MIDDLE 80S EACH DAY, EXCEPT A BIT COOLER NEAR  
LAKE MICHIGAN. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS THIS  
AFTERNOON, THEN A CHANCE FOR SHOWERS AND THUNDERSTORMS ON  
WEDNESDAY, AND AGAIN LATE THURSDAY NIGHT INTO FRIDAY. TEMPERATURES  
WILL TREND COOLER, MORE SEASONABLE THIS WEEKEND INTO EARLY NEXT  
WEEK.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 322 AM EDT TUE SEP 18 2018  
 
LIKE A BROKEN RECORD, FOG WAS BEEN SEEN IN AREAS FOR YET ANOTHER  
MORNING. BY IN LARGE IT IS NOT CAUSING MANY IMPACTS BUT POCKETS OF  
BRIEF DENSE FOG HAVE BEEN NOTED. WILL MONITOR TRENDS BUT NOT  
EXPECTED TO BE WIDESPREAD ENOUGH TO WARRANT MUCH MORE THAN A SPS  
AT THIS POINT. UPSTREAM CONVECTION ACROSS MINNESOTA WILL BE THE  
MAIN FOCUS INTO TODAY. SERIES OF OUTFLOW BOUNDARIES, PRE- FRONTAL  
TROUGH AND FRONTAL BOUNDARY WILL ALL DRIFT SOUTHEAST INTO THE AREA  
FOR MUCH OF THIS PERIOD AND INTO THE LONG TERM. NAMNEST APPEARS  
TO HAVE BEST HANDLING OF CURRENT SITUATION WITH IT AND TO A LESSER  
EXTENT HRRR/ARW SHOWING DECAYING STORMS MOVING TOWARDS THE AREA  
THIS MORNING. HAVE BACKED OFF POPS THROUGH THE MORNING WITH TIMING  
OF UPSTREAM CONVECTION AND LIKELY WEAKENING STATE ALL EXPECTED TO  
REDUCE ANY CHANCES FOR MEASURABLE. LEFT TOKEN SLGT CHC POPS THIS  
AFTERNOON WITH RESIDUAL BOUNDARIES AROUND. HIGHS TODAY WILL VARY  
FROM NORTH TO SOUTH WITH WARMEST READINGS IN THE SOUTH (MID- UPR  
80S VS UPR 70S-LOW 80S).  
 
BRIEF LULL MAY TAKE PLACE IN PRECIP CHANCES BUT MAIN FRONTAL  
BOUNDARY WILL BE IN THE AREA BY LATER TONIGHT INTO THE LONG TERMS  
PERIOD TO BRING NON-ZERO CHANCES FOR A POP UP SHOWER/STORM.  
THERMAL PROFILES DON'T CHANGE A WHOLE LOT WITH MAIN FORCING AND  
COLDEST AIR REMAINING WELL NW OF THE AREA. LOWS IN THE 60S ARE  
EXPECTED. MODELS HAVE BEEN HINTING AT SLIGHTLY BETTER CHANCE FOR  
SOME FOG TONIGHT BUT WON'T ADD AT THIS POINT.  
 

 
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 322 AM EDT TUE SEP 18 2018  
 
FRONTAL BOUNDARY WILL RESIDE NEAR/SOUTH OF THE AREA DURING THE DAY  
WEDNESDAY WITH YET ANOTHER COMPLEX OF STORMS EXPECTED UPSTREAM  
TUESDAY NIGHT WHICH MAY MOVE INTO NW AREAS WEDS MORNING. LEFTOVER  
OUTFLOW BOUNDARY MAY PROVIDE FOCUS FOR ADDITIONAL CONVECTION WEDS  
AFTERNOON BEFORE MAIN SYNOPTIC FRONT STARTS TO PUSH BACK NORTH WEDS  
NIGHT INTO THURSDAY WITH YET ANOTHER COMPLEX ALONG IT. MODELS VARY  
GREATLY ON IMPACTS GIVEN WHAT WILL BE A CHALLENGING ENVIRONMENT.  
WILL MAINTAIN MID RANGE CHC POPS UNTIL FRONT PUSHES BACK NORTH ON  
THURSDAY. LOCATIONS SOUTH OF THE FRONT WILL BREEZY CONDITIONS AND  
HIGHS WELL INTO THE 80S, WITH 850 MB TEMPS PUSHING 20 C SUGGESTING A  
FEW SPOTS COULD APPROACH/EXCEED 90.  
 
STRONGER COLD FRONT AND ASSOCIATED UPPER LEVEL TROUGH WILL FINALLY  
SWING THROUGH DURING THE DAY FRIDAY WITH CHANCE OF SHOWERS AND  
STORMS ALONG IT. COVERAGE SOMEWHAT QUESTIONABLE STILL WITH BEST  
DYNAMICS REMAINING WELL NORTH BUT SHOULD STILL BE ENOUGH FOR MID TO  
HIGH CHC POPS. MORE SEASONABLE AIR WILL ARRIVE BEHIND THE FRONT INTO  
THE WEEKEND AND EARLY NEXT WEEK WITH HIGHS IN THE 60S TO LOWER  
70S AND LOWS IN THE 50S.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON)  
ISSUED AT 1256 PM EDT TUE SEP 18 2018  
 
CONVECTIVE ACTIVITY LIKELY TO REMAIN SUPPRESSED AMID OUTFLOW  
DOMINANT ENVIRONMENT AND NOMINAL INSTABILITY ACROSS NORTHERN  
INDIANA. CONCERN REMAINS FOR BRIEF VISIBILITY REDUCTION NEAR  
SUNRISE IN SHALLOW/PATCHY FOG, THOUGH OVERALL ANY REDUCTIONS  
SHOULD BE MINOR/BRIEF. LATER FORECAST ISSUANCES TO FURTHER ASSESS  
THUNDERSTORM POTENTIAL LATER WEDNESDAY AFTERNOON.  
 

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

 
 

 
 
SYNOPSIS...FISHER  
SHORT TERM...FISHER  
LONG TERM...FISHER  
AVIATION...MURPHY  
 
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WWW.YOUTUBE.COM/NWSNORTHERNINDIANA  
 
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