472  
FXUS63 KIWX 201010  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
610 AM EDT SUN AUG 20 2017  
   
SYNOPSIS
 
 
ISSUED AT 318 AM EDT SUN AUG 20 2017  
 
HIGH PRESSURE OVER THE APPALACIANS WILL CONTINUE TO PROVIDE FAIR  
WEATHER ACROSS OUR AREA TODAY THROUGH MONDAY MORNING. THE SOUTHERLY  
FLOW AROUND THIS HIGH WILL RESULT IN WARMER AND MORE HUMID  
CONDITIONS THE NEXT COUPLE OF DAYS. A STRONG COLD FRONT WILL MOVE  
SOUTHEAST ACROSS OUR AREA TUESDAY, WITH SHOWERS AND SCATTERED  
THUNDERSTORMS LIKELY ALONG AND AHEAD OF THE FRONT. HIGH PRESSURE  
WILL MOVE SLOWLY EAST ACROSS THE GREAT LAKES WEDNESDAY THROUGH  
FRIDAY, AND TO THE NEW ENGLAND COAST THIS WEEKEND PROVIDING DRY  
WEATHER ACROSS OUR AREA THROUGH THIS TIMEFRAME. TEMPERATURES WILL BE  
WELL BELOW NORMAL LATE THIS WEEK, BUT A GRADUAL WARMING TREND IS  
EXPECTED OVER THE WEEKEND.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT AND MONDAY)  
ISSUED AT 318 AM EDT SUN AUG 20 2017  
 
CLUSTER OF TSTMS OVER ERN NEB/WRN IA EXPECTED TO MOVE EAST TODAY BUT  
SHOULD DISSIPATE OR CURVE SE TOWARD GREATER INSTABILITY BEFORE  
REACHING OUR AREA. MOSTLY SUNNY SKIES AND WK WAA SHOULD ALLOW TEMPS  
TO REACH THE M80S ACROSS OUR AREA THIS AFTN. ANOTHER CLUSTER OF  
STORMS EXPECTED TO DEVELOP A LITTLE FARTHER EAST OVER IA AT NOSE OF  
LLJ TONIGHT. MCV FROM THIS ACTIVITY SHOULD DRIFT EAST ACROSS OUR  
AREA MONDAY AFTN AS DIURNAL INSTABILITY CONTS TO INCREASE. AN  
ISOLATED SHOWER PSBL NW PORTION OF THE CWA IN ENHANCED LOW LEVEL  
WAA/WINDS AHEAD OF THIS FEATURE LATE TONIGHT AND MONDAY MORNING  
BUT BETTER CHANCE AS IT MOVES THROUGH MONDAY AFTN. WITH VERY WARM  
AIRMASS IN PLACE BY MONDAY, EXPECT SUFFICIENT HEATING FOR TEMPS  
TO MIX OUT INTO THE U80S, BARRING UNFORESEEN WIDESPREAD  
CONVECTION OR SGFNT OUTFLOW BOUNDARY DISRUPTION.  
 

 
   
LONG TERM
 
(MONDAY NIGHT THROUGH SATURDAY)  
ISSUED AT 318 AM EDT SUN AUG 20 2017  
 
STRONG SHRTWV WILL DIG SE ACROSS THE UPR GRTLKS MON NGT-TUE WITH  
ASSOCIATED SFC CDFNT MOVG ACROSS OUR AREA TUE. NAM/GFS/ECMWF/GEM  
IN DECENT AGREEMENT SUGGESTING SHOWERS/TSTMS WILL OVERSPREAD OUR  
AREA AHEAD OF THE FRONT LATE MONDAY NIGHT AND TUE MORNING DURING A  
PERIOD OF RELATIVELY LOW INSTABILITY. THIS CONVECTION WOULD LIKELY  
LIMIT DESTABILIZATION TUE AS THE FRONT MOVES THROUGH. HOWEVER, NAM  
3KM SUGGESTS THIS PRE-FRONTAL CONVECTION WILL ONLY IMPACT THE  
N-NW PORTION OF THE CWA MONDAY NIGHT, PSBLY ALLOWING FOR MORE  
SGFNT DESTABILIZATION ACROSS THE S-SE PORTION TUE AHEAD OF THE  
FRONT. IF SGFNT DESTABILIZATION DOES OCCUR, A FEW SVR STORMS PSBL  
AS STRONG DEEP LAYER SHEAR SHOULD BE IN PLACE BY THAT TIME.  
 
SFC HIGH WILL MOVE SLOWLY ESE FROM THE NRN PLAINS TUE NGT ACROSS THE  
GRTLKS THU-SAT, AND TO THE NEW ENGLAND COAST BY SUNDAY PROVIDING DRY  
CONDITIONS THROUGH THIS PERIOD. TEMPS WILL BE WELL BLO NORMAL WED-  
FRI BUT GRDLY WARM BACK TO NEAR NORMAL OVER THE WEEKEND AS DEEP ERN  
U.S. UPR LEVEL TROF MOVES SLOWLY EAST AND WK RIDGING CROSSES THE  
GRTLKS.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 608 AM EDT SUN AUG 20 2017  
 
VFR CONDITIONS TO PREVAIL WITH LITTLE MORE THAN SOME CU AROUND  
THIS AFTERNOON AND THIN CIRRUS FROM UPSTREAM CONVECTION. WINDS  
WILL REMAIN UNDER 6 KNOTS.  
 

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

 
 

 
 
SYNOPSIS...JT  
SHORT TERM...JT  
LONG TERM...JT  
AVIATION...FISHER  
 
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