656  
FXUS63 KIWX 311737  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
137 PM EDT MON AUG 31 2015  
   
SYNOPSIS
 
 
ISSUED AT 1152 AM EDT MON AUG 31 2015  
 
HIGH PRESSURE WILL BE OVER THE REGION THROUGH TONIGHT. MUGGY  
AND WARM CONDITIONS TODAY AS SKIES WILL BE PARTLY CLOUDY AND HIGH  
TEMPERATURES REACH INTO THE MIDDLE 80S. TONIGHT TEMPERATURES WILL  
DROP ONLY TO THE MIDDLE TO UPPER 60S AS A CHANCE FOR SOME FOG  
RETURNS TO THE NORTHERN PART OF THE REGION.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 334 AM EDT MON AUG 31 2015  
 
MAINLY CLEAR SKIES, CALM WINDS, AND ELEVATED SFC DEWPOINTS HAS  
ALLOWED WIDESPREAD FOG TO DEVELOP NORTHWEST OF A DIFFUSE SFC  
TROUGH EARLY THIS MORNING...MAINLY ALONG/NORTHWEST OF THE HWY 24  
CORRIDOR. GIVEN CURRENT OBS, HIGH SFC-900 MB RH FIELDS, AND WHAT  
OCCURRED UPSTREAM YESTERDAY HAVE OPTED FOR A DENSE FOG ADVISORY  
THROUGH 13Z IN THESE AREAS. DIURNAL MIX OUT/UP TO A SCT-BKN CU  
FIELD IS THEN EXPECTED MID MORNING INTO EARLY AFTERNOON.  
 
BUILDING HEAT/INSTABILITY FOR THE AFTERNOON MAY ALLOW A FEW POP  
UP STORMS TO FIRE AMID THE AFOREMENTIONED WEAK SFC  
TROUGH...LOCATED ON THE NORTHERN FRINGE OF LEFTOVER WEAKNESS IN  
THE MID/UPPER LEVEL HEIGHT FIELD. THIS FAVORS AREAS MAINLY SE OF  
THE HWY 24 CORRIDOR IN INDIANA AND OHIO FOR A MENTIONABLE LOW POP.  
DRY/WARM OTHERWISE WITH FOG POSSIBLY A CONCERN ONCE AGAIN LATER  
TONIGHT IN THE SAME AREAS.  
 
 

 
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 334 AM EDT MON AUG 31 2015  
 
PREVIOUS FORECAST APPEARS TO BE IN GOOD SHAPE FOR THE LONG TERM  
PERIOD WITH MAIN FORECAST THEMES CENTERING ON INCREASED HEAT...AND  
DIURNALLY ENHANCED POTENTIAL OF ISOLATED SHOWERS/STORMS.  
 
FOR TUESDAY/TUESDAY NIGHT MAIN FEATURE OF INTEREST WILL BE  
RESIDUAL VORT MAX FROM SYSTEM WHICH SHEARED OUT OVER THE LOCAL  
AREA YESTERDAY. WATER VAPOR IMAGERY MORNING DEPICTING SOME  
DISCERNIBLE UPPER LEVEL CIRCULATION WITH THIS FEATURE...AND COULD  
BE ENOUGH FORCING FOR ISOLATED SHOWERS/STORMS MAINLY DURING PEAK  
HEATING ON TUESDAY. DESPITE LOW LEVEL WAA BEGINNING TO RAMP UP IN  
THE AFTERNOON...EFFECTS FROM WAA INDUCED CLOUDS/DPVA ASSOCIATED  
WITH VORT MAX SHOULD LIMIT HIGHS TO THE LOWER TO MID 80S FOR MOST  
LOCATIONS. HAVE KEPT TUESDAY NIGHT DRY AT THIS TIME BUT SOME  
POSSIBILITY MAY EXIST FOR ISOLATED SHOWER DEVELOPMENT DUE TO  
COMBINATION OF MEANDERING VORT MAX AND SOME ISENTROPIC ASCENT  
ASSOCIATED WITH DEPARTING COOL POCKET. WEDNESDAY POPS MAY BE A BIT  
MORE QUESTIONABLE WITH CONSENSUS OF LATEST DETERMINISTIC GUIDANCE  
TENDING TO DRIFT THIS VORT MAX SOUTHEAST OF THE AREA. HESITANT TO  
PULL ISO POPS FOR WEDNESDAY HOWEVER GIVEN BROAD ISENTROPIC ASCENT  
COUPLED WITH DIURNAL INSTABILITY...SO NO MAJOR CHANGES MADE TO  
PREVIOUS FORECAST. BIGGER STORY FOR THE MID WEEK PERIOD WILL BE  
THE TRANSITION TO ABOVE NORMAL TEMPS...WITH EXPECTED BETTER  
INSOLATION ON WEDNESDAY AND WAA ALLOWING HIGHS TO REACH INTO THE  
UPPER 80S MOST LOCATIONS.  
 
FOR THURSDAY AND FRIDAY IT STILL APPEARS AS THOUGH VERY WEAK  
PACIFIC ORIGIN WAVES MAY TRY TO PROGRESS THROUGH BUILDING UPPER  
LEVEL RIDGING ACROSS THE REGION. HOWEVER...WILL KEEP FORECAST DRY  
AT THIS TIME GIVEN WEAK NATURE OF FORCING AND THE LIKELY MORE  
QUESTIONABLE SFC BASED INSTABILITY BY THIS TIMEFRAME. WARM  
CONDITIONS TO CONTINUE THROUGH THE WEEKEND...ALTHOUGH BUILDING  
ANTICYCLONE ACROSS SOUTHEAST CANADA/NORTHEAST CONUS SHOULD TEND TO  
ALLOW NORTHEAST LOW LEVEL FLOW TO EVOLVE ACROSS THE REGION KEEPING  
TEMPS IN CHECK INTO MID 80S. THE NEXT CHANCE OF MENTIONABLE PRECIP  
SHOULD HOLD OFF UNTIL AFTER THIS FORECAST PERIOD WITH THE  
POTENTIAL OF A MORE SIGNIFICANT UPPER TROUGH MOVING ACROSS NORTH  
CENTRAL CONUS.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON)  
ISSUED AT 125 PM EDT MON AUG 31 2015  
 
VFR CONDITIONS FOR MUCH OF FORECAST PD. HOWEVER...POTENTIAL  
EXISTS YET AGAIN FOR PERIOD OF IFR VSBYS IN BR/FG ACROSS NRN IN.  
RELATIVELY LACKLUSTER MIXOUT TODAY/HIGH AFTERNOON DEWPOINTS BODE  
WELL FOR BR FORMATION TOWARD DAYBREAK AS SHARP SFC BASED INVERSION  
PEAKS 10-12 UTC.  
 

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

 
 

 
 
SYNOPSIS...LOTHAMER  
SHORT TERM...STEINWEDEL  
LONG TERM...MARSILI  
AVIATION...MURPHY  
 
VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE)  
 
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:  
WWW.FACEBOOK.COM/NWSNORTHERNINDIANA  
WWW.TWITTER.COM/NWSIWX  
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA  
 
CLICK HERE TO GO TO PREVIOUS BULLETINS.

The Nexlab IN Page
The Nexlab OH Page
The Nexlab MI Page Main Text Page