655  
FXUS63 KIWX 201041  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
641 AM EDT WED SEP 20 2017  
   
SYNOPSIS
 
 
ISSUED AT 400 AM EDT WED SEP 20 2017  
 
VISIBILITIES COULD BE NEAR ZERO IN SOME LOCATIONS AROUND DAYBREAK  
AS FOG CONTINUES TO DEVELOP. THE FOG WILL DISSIPATE BY LATE  
MORNING WITH MOSTLY SUNNY SKIES IN THE AFTERNOON. HIGH  
TEMPERATURES WILL RISE WELL INTO THE 80S. VERY WARM AND DRY  
CONDITIONS WILL CONTINUE FOR THE REMAINDER OF THE WEEK AND INTO  
THE WEEKEND WITH HIGHS IN THE MIDDLE TO UPPER 80S AND EVEN SOME  
LOWER 90S POSSIBLE.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 401 AM EDT WED SEP 20 2017  
 
SURFACE TEMPS TO FALL WELL BELOW CROSSOVER AND WITH RECENTLY WETTED  
GROUND ANTICIPATE FOG TO BECOME MORE DENSE/PREVALENT THROUGH  
SUNRISE. DENSE FOG ADVISORY FOR ALL BUT FAR EAST/SOUTHEAST CWA WHERE  
DENSER CLOUD COVERAGE LIMITING OUTGOING LONGWAVE RADIATION.  
OTHERWISE MODERATING LOW LEVEL THERMAL PROFILE IN ADVANCE OF SLOWING  
FRONTAL BOUNDARY TO AFFORD STRONG DIURNAL RISES WITH SURFACE TEMPS  
ON ORDER OF 10F HIGHER THAN YESTERDAY. STEEPENING SURFACE LAPSE  
RATES ALSO TO AFFORD MIXOUT OF FOG NO LATER THAN 14 UTC.  
 

 
   
LONG TERM
 
(THURSDAY THROUGH TUESDAY)  
ISSUED AT 401 AM EDT WED SEP 20 2017  
 
STOIC RIDGING FROM EASTERN TX INTO THE UPPER GREAT LAKES BETWEEN  
ACTIVE EASTERN ATLANTIC AND DIGGING WESTERN STATES TROUGH.  
CONTINUED STAGNATION/THERMAL MODERATION TO BRING QUITE WARM/HUMID  
AIRMASS THROUGH REMAINDER OF WEEK AS STALLED FRONTAL BOUNDARY W-N  
DECAYS. WITH TIME LEESIDE ROCKIES TROF TO ESTABLISH SLOW EASTWARD  
MOVING FRONTAL BOUNDARY THAT MAY PROVIDE CHANCE OF CONVECTION BY  
ABOUT MIDDLE OF NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING)  
ISSUED AT 639 AM EDT WED SEP 20 2017  
 
LIFR CONDITIONS WILL IMPROVE OVER THE NEXT COUPLE OF HOURS AS  
MIXING INCREASES. ONCE THE FOG IS GONE, VFR CONDITIONS ARE  
EXPECTED THROUGH THE REMAINDER OF THE PERIOD.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...DENSE FOG ADVISORY UNTIL 10 AM EDT /9 AM CDT/ THIS MORNING FOR  
INZ003>009-012>018-020-022>025.  
 
MI...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR MIZ077>081.  
 
OH...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR OHZ001-002-  
004.  
 
LM...NONE.  

 
 

 
 
SYNOPSIS...MURPHY  
SHORT TERM...MURPHY  
LONG TERM...MURPHY  
AVIATION...FISHER  
 
VISIT US AT WWW.WEATHER.GOV/IWX  
 
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WWW.TWITTER.COM/NWSIWX  
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