382  
FXUS63 KDVN 282356  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
656 PM CDT WED JUN 28 2017  
   
..AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 323 PM CDT WED JUN 28 2017  
 
THUNDERSTORMS HAVE BEEN FESTERING OVER THE FORECAST AREA THROUGH  
MUCH OF THE AFTERNOON IN THE WAKE OF THE EARLY MORNING HEAVY  
RAIN PRODUCING STORMS. THESE STORMS HAVE RECENTLY STRENGTHENED  
SOME SOUTH OF THE QUAD CITIES. IN THE BIG PICTURE, AN UPPER LEVEL  
SHORTWAVE WAS MOVING ACROSS NORTHERN IA AND A 60 KT UPPER LEVEL  
JET MAX IS MOVING INTO WESTERN IOWA CAUSING AN UPTICK IN STORMS  
OVER NORTHERN AND WESTERN IA AND ALONG THE MO RIVER IN SOUTHWEST  
IA. DEEP SHEAR AND INCREASING INSTABILITY WILL FAVOR SEVERE STORM  
DEVELOPMENT AND A TORNADO WATCH WAS JUST ISSUED FOR MOST OF IA AND  
NORTHERN MO.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 323 PM CDT WED JUN 28 2017  
 
SEVERE WEATHER AND HEAVY RAINFALL WILL BE THE FOCUS OVERNIGHT  
THROUGH AT LEAST THURSDAY NIGHT. DEVELOPING SEVERE STORMS OVER  
WESTERN AND NORTHERN IA WILL LIKELY EVOLVE INTO A MORE LINEAR  
STRUCTURE OVERNIGHT AND ADVANCE SOUTHEAST OVER ESPECIALLY THE  
SOUTHERN HALF OF THE LOCAL FORECAST AREA. LIKE LAST NIGHT, THE  
WITH ABUNDANT MOISTURE, WILL CONTINUE A HEAVY RAIN THREAT. DEEPER  
WIND SHEAR, HIGH CAPES AND POSSIBLY BOUNDARY INTERACTIONS WILL  
LEAD TO AN ENHANCED SEVERE RISK WITH ALL MODES INCLUDING LARGE  
HAIL, DAMAGING WINDS AND TORNADOES, ESPECIALLY LATE THIS AFTERNOON  
THROUGH EVENING. FROM LATE EVENING THROUGH OVERNIGHT, THE SEVERE  
THREAT WILL LIKELY DIMINISH, BUT WILL HAVE TO WATCH FOR ANY  
POSSIBLE BACK-BUILDING FOR A HEAVY RAINFALL THREAT, ESPECIALLY  
OVER THE FORECAST AREA SOUTH OF I-80.  
 
FORECAST MODELS LARGELY CONTINUE THE IDEA OF THE MAIN BOUNDARY  
STALLING FROM WEST TO EAST ACROSS SOUTHERN IA OR NORTHERN MO LATE  
TONIGHT AND REMAINING THERE THROUGH THURSDAY. ADDITIONAL MID LEVEL  
SHORTWAVES AND HIGH LEVELS OF MOISTURE ON A SOUTHWEST LOW LEVEL  
FLOW IMPINGING ON THE BOUNDARY WILL CONTINUE THE RISK FOR HEAVY  
RAINFALL AND AT LEAST A SLIGHT RISK FOR SEVERE WEATHER AS  
DEMONSTRATED BY THE SPC DAY 2 OUTLOOK WITH A SLIGHT RISK OVER MOST  
OF THE FORECAST AREA.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 323 PM CDT WED JUN 28 2017  
 
ANOTHER WAVE OF SHOWERS AND THUNDERSTORMS IS POSSIBLE FOR LATE  
FRIDAY INTO SATURDAY AHEAD OF ANOTHER SHORTWAVE TRAVERSING  
THROUGH BROAD UPPER MIDWEST/GREAT LAKES TROUGH. HOWEVER,  
CONDITIONS WILL NOT BE AS CONDUCIVE FOR HEAVY RAINFALL.  
 
SEMI-ZONAL TO W/NW FLOW LOOKS TO KEEP THINGS SOMEWHAT UNSETTLED  
LATE WEEKEND THROUGH EARLY NEXT WEEK WITH PERIODIC SHOWER  
CHANCES. TEMPERATURES LOOK TO BE NEAR TO SLIGHTLY BELOW NORMAL  
THROUGHOUT THE PERIOD.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 655 PM CDT WED JUN 28 2017  
 
CLUSTERS OF STRONG TO SEVERE STORMS WITH DAMAGING WIND, LARGE HAIL  
AND VERY HEAVY RAINFALL WILL CONTINUE TO MOVE THROUGH EASTERN IOWA  
EARLY THIS EVENING. THERE WILL LIKELY BE A BREAK IN THE STORMS  
OVERNIGHT, THEN ADDITIONAL STORMS THURSDAY MORNING IN THE  
BURLINGTON AREA, THEN POSSIBLY AFFECTING ALL TERMINALS THURSDAY  
AFTERNOON. HAVE KEPT CONDITIONS PREVAILING VFR, BUT THERE WILL BE  
A POTENTIAL FOR MVFR LOW CLOUDS AND FOG BEHIND THE RAIN, WHICH IS  
NOT MENTIONED IN THE FORECASTS.  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...NONE.  
IL...NONE.  
MO...NONE.  

 
 

 
 
SYNOPSIS...SHEETS  
SHORT TERM...SHEETS  
LONG TERM...SHEETS  
AVIATION...SHEETS  
 
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