535  
FXUS63 KIWX 131022  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
622 AM EDT MON JUL 13 2020  
   
SYNOPSIS
 
 
ISSUED AT 327 AM EDT MON JUL 13 2020  
 
AVERAGE TO SLIGHTLY BELOW AVERAGE TEMPERATURES WITH LOWER HUMIDITY ARE  
IN PLACE FOR TODAY AND TUESDAY WITH JUST A MIX OF SUN AND CLOUDS.  
HIGH TEMPERATURES AS WELL AS CHANCES FOR SHOWERS AND  
THUNDERSTORMS INCREASE FOR WEDNESDAY AS A LOW PRESSURE SYSTEM  
APPROACHES. REMAINING WARM AND UNSETTLED LATE WEEK.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 327 AM EDT MON JUL 13 2020  
 
MID LEVEL RIDGE AXIS SLIDES EAST ARRIVING LATE TONIGHT. THIS  
ALLOWS THE LOW LEVEL JET TO STAY WEAK DURING THE PERIOD. SO, WHILE  
THERE IS SOME WEAK LOW LEVEL INSTABILITY AND LAPSE RATES UP TO  
850 MB, WINDS SHOULD STAY LIGHT AND AM EXPECTING JUST A MIX OF SUN  
AND CLOUDS AROUND DURING THE DAY AS WEAK SHORTWAVES MOVE THROUGH  
IN THE NORTHWEST FLOW.  
 
HIGH TEMPERATURES TODAY SHOULD BE CLOSE TO SUNDAY'S WITH 850 MB  
TEMPS FAIRLY CLOSE TO, IF NOT SLIGHTLY COOLER THAN, SUNDAY'S. THIS  
SHOULD PUT US IN THE LOW 80S FOR HIGHS. THEN FOR MONDAY NIGHT,  
MINIMAL CLOUDINESS, DRIER DEW POINTS AND LIGHT WINDS SHOULD HELP US  
FALL BACK TOWARDS THE LOW 60S, EXCEPT UPPER 50S WEST OF US-31.  
 

 
   
LONG TERM
 
(TUESDAY THROUGH SUNDAY)  
ISSUED AT 327 AM EDT MON JUL 13 2020  
 
THE LONG TERM IS CHARACTERIZED BY A TRANSITION FROM A TROUGH EAST,  
RIDGE WEST PATTERN TO A TROUGH WEST, RIDGE EAST PATTERN. THE PATTERN  
TRANSITION OCCURS AS A WAVE (OUR NEXT PRECIP CHANCE) APPROACHES THE  
AREA WEDNESDAY. SOME MODEL DISAGREEMENT STILL EXISTS WITH THE TRACK  
THAT THIS WAVE TAKES TO GET TOWARDS THE AREA SO SOME MODELS HAVE THE  
PRECIPITATION STARTING BEFORE 18Z. WOULD RATHER SIDE WITH THE EC AND  
LET THE DIURNAL FORCING OF THE AFTERNOON AND THE WAVE GET CLOSER TO  
THE AREA TO HELP GET PRECIP GOING ACROSS OUR NORTH. AS SUCH, WILL  
LEAVE THE 15-20 POPS IN FOR AREAS WEST OF US-31 AND NEAR THE LAKE  
FOR WED, BUT THE BETTER CHANCE FOR POPS IS DEFINITELY IN THE  
AFTERNOON, ESPECIALLY WITH THE THETA-E BOUNDARY STILL DEPICTED ALONG  
THE IL/IN BORDER AT 18Z. THUNDERSTORM POTENTIAL IS THERE FOR LATER  
WEDNESDAY DEPENDING ON ITS TIMING WITH SBCAPE BEING MODELED TO RISE  
ABOVE 1500 J/KG. SOME SHEAR IS AROUND, BUT IT'S RATHER MARGINAL AT  
BETWEEN 20-30 KTS AND COULD BE BOUNDARY PARALLEL, WHICH COULD LEAD  
TO SOME TRAINING OF CELLS AND PERHAPS EVEN SOME SLOW-MOVING ONES  
ESPECIALLY WITH THE INCREASED MOISTURE. GUSTY WINDS ARE ALSO  
POSSIBLE WITH THIS EVENT.  
 
ANYWAYS, BACK TO TUESDAY, THE AFOREMENTIONED UPPER RIDGE AXIS IS  
STILL ACROSS THE AREA ALLOWING ANOTHER DAY OF QUIET WEATHER.  
HOWEVER, SIMILAR MIXING HEIGHTS TO TODAY, BUT WARMER 850 MB  
TEMPERATURES ALLOW FOR A WARMER DAY, MORE LIKE THE MID 80S AS  
OPPOSED TO LOW 80S FOR HIGHS. THE AREA COULD START TO FEEL A SLIGHT  
INCREASE IN HUMIDITY BY THE END OF THE DAY, ESPECIALLY AREAS WEST OF  
US-31, BUT THE BETTER CHANCE FOR NOTICEABLY INCREASED HUMIDITY  
OCCURS WEDNESDAY.  
 
THE PRECIP CHANCE FOR WEDNESDAY WAS DISCUSSED ABOVE, BUT TEMPERATURE-  
WISE, WEDNESDAY LIKELY SEES MANY AREAS REACHING THE UPPER 80S, BUT  
COULD SEE A FEW AREAS REACH 90 DEGREES WITH THE INCREASED WARMTH,  
ESPECIALLY IF THE HIGHER DEW POINT AIR (~70F) WAITS UNTIL LATER DAY  
LIKE THE EC DEPICTS.  
 
THEN, IT APPEARS THE THETA-E BOUNDARY ACTUALLY LINGERS NEARBY FOR  
THURSDAY AND FRIDAY SO WILL HOLD ONTO THE BLENDED POPS THERE,  
WHICH ARE ACCOMPANIED BY THUNDER. THE POTENTIAL FOR SPOTS THAT  
REACH 90 DEGREE TEMPS RETURN FOR FRIDAY AND THE WEEKEND.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)  
ISSUED AT 620 AM EDT MON JUL 13 2020  
 
HIGH PRESSURE SETTLES IN TO PROMOTE VFR CONDITIONS WITH MOSTLY  
CLEAR SKIES. LIGHT NORTHERLY WINDS THIS MORNING INCREASE TO 5-10 KTS  
DURING THE DAY. FAIR WEATHER CUMULUS MAY DOT THE AREA IN THE  
AFTERNOON.  
 

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

 
 

 
 
SYNOPSIS...ROLLER  
SHORT TERM...ROLLER  
LONG TERM...ROLLER  
AVIATION...COBB  
 
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WWW.TWITTER.COM/NWSIWX  
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA  
 
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