387  
FXUS63 KIWX 091041  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
641 AM EDT SUN AUG 9 2020  
   
SYNOPSIS
 
 
ISSUED AT 307 AM EDT SUN AUG 9 2020  
 
DRY CONDITIONS TODAY INTO THIS EVENING WILL GIVE WAY TO CHANCES  
FOR SHOWERS AND THUNDERSTORMS LATER TONIGHT THROUGH MONDAY NIGHT.  
BECOMING HUMID OTHERWISE WITH HIGHS BETWEEN 85 AND 90 DEGREES.  
MAINLY DRY CONDITIONS AND SEASONABLE TEMPERATURES INTO TUESDAY  
AND WEDNESDAY WILL BE FOLLOWED BY PERIODIC CHANCES FOR SHOWERS AND  
THUNDERSTORMS THURSDAY AND FRIDAY.  
 

 
   
SHORT TERM
 
(TODAY THROUGH MONDAY NIGHT)  
ISSUED AT 307 AM EDT SUN AUG 9 2020  
 
RIDGING ALOFT WILL ALLOW FOR ANOTHER DRY/MOSTLY SUNNY DAY WITH  
CONVECTION FOCUSED NEAR A SFC WARM FRONT IN THE MID MS VALLEY,  
AND UP ACROSS THE UPPER MIDWEST/NORTHERN LAKES ON SOUTHERN FRINGE  
OF WESTERLIES. LOW LEVEL SOUTHWEST FLOW WILL ALLOW FOR AN UPTICK  
IN TEMPS AND HUMIDITY OTHERWISE WITH HIGHS INTO THE UPPER 80S  
 
FOLD OVER OF DEEPER UPSTREAM MOISTURE WILL ALLOW SHOWER/STORM  
CHANCES TO ENTER THE FORECAST LATER TONIGHT THROUGH MONDAY EVENING.  
FOCUS INITIALLY WILL RELY ON A REMNANT OUTFLOW/MCV TO SPILL  
SOUTHEAST INTO THE AREA FROM THE UPPER MIDWEST INTO SW MI AND  
WESTERN IN. POOR DIURNAL TIMING AND OUTRUN FROM BETTER SUPPORT  
SUPPORTS A WEAKENING TREND AND LOW-MID CHANCE POPS MONDAY  
MORNING/EARLY AFTERNOON. IF THIS OUTFLOW AND POSSIBLE MCV IS  
SLOWER, ALLOWING FOR GREATER DIURNAL HEATING, THERE COULD BE AN  
UPTICK IN CONVECTION MID-LATE AFTN INTO NE IN/SC MI/NW OH.  
RELIANCE ON THESE SMALLER SCALE (CONVECTIVELY AIDED) FEATURES  
MAKES FOR A LOW CONFIDENCE FCST AND NOTHING MORE THAN A LOW-MID  
CHANCE POP.  
 
A COLD FRONT WILL TRAIL A NORTHERN LAKES SHORTWAVE INTO THE AREA  
MONDAY NIGHT WITH SLIGHTLY BETTER PROSPECTS FOR SHOWERS AND  
STORMS, ESPECIALLY WESTERN ZONES LATE EVENING/EARLY OVERNIGHT AS  
AMPLE MOISTURE AND THE POTENTIAL FOR ANOTHER CONVECTIVELY AIDED  
VORT ACCOMPANIES THE SOUTHWARD SAGGING FRONT.  
 

 
   
LONG TERM
 
(TUESDAY THROUGH SATURDAY)  
ISSUED AT 307 AM EDT SUN AUG 9 2020  
 
SLOW MOVING CONVECTIVE COMPLEXES AND A LINGERING INSTABILITY  
GRADIENT WILL IMPACT THE MID MS/OH VALLEYS MID-LATE WEEK, WHILE  
RIDGING ALOFT AND AT THE SFC BUILDS OVER THE GREAT LAKES AND SE  
CANADA. THIS REGIME SHOULD BE ENOUGH TO KEEP THE BULK OF  
SHOWER/STORM ACTIVITY SSW OF THE AREA TUESDAY INTO WEDNESDAY, THOUGH  
SOME LOWER POPS REMAIN OVER SOUTHERN ZONES GIVEN CLOSE PROXIMITY  
TO THE LINGERING BOUNDARY. RETAINED BROADBRUSH LOW-MID CHANCE POPS  
AREA-WIDE (HIGHEST PM) THEREAFTER AS CONFIDENCE WANES REGARDING  
POSITIONING OF THE BOUNDARY AND TRACK/TIMING OF A SLOW MOVING MID  
MS TROUGH. SEASONAL TEMPS OTHERWISE WITH HIGHS GENERALLY LOW-MID  
80S.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 640 AM EDT SUN AUG 9 2020  
 
VFR CONDITIONS THROUGH THE FORECAST PERIOD. EASTERN FLANK OF  
HIGHER SURFACE DEWPOINTS/DIURNAL INSTABILITY POOL TO PROGRESS  
GRADUALLY EASTWARD FROM MID MISSISSIPPI VALLEY/UPPER MIDWEST INTO  
NORTHERN INDIANA THROUGH THE FORECAST PERIOD. FOCUS FOR DEEP  
MOIST CONVECTION HOWEVER, APPEARS TIED TO NORTHERN STREAM  
SHORTWAVE WELL UPSTREAM WITH POSSIBLE DECAYING MESOSCALE  
CONVECTIVE SYSTEM ARRIVAL LATE IN THE FORECAST PERIOD INTO KSBN.  
CHANCES APPEAR QUITE LOW AT THIS TIME AND OPT TO EXCLUDE MENTION.  
 

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

 
 

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