147  
FXUS63 KDVN 212316  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
616 PM CDT TUE AUG 21 2018  
   
..00Z AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 246 PM CDT TUE AUG 21 2018  
 
THE SYNOPTIC LOW WHICH BROUGHT HEAVY RAIN AND WIDESPREAD CLOUD OVER  
TO THE MIDWEST YESTERDAY, IS SLOWLY WEAKENING AND MOVE WELL TO THE  
EAST. MID LEVEL DRY AIR HAS LIMITED SHOWER DEVELOPMENT IN OUR AREA  
TODAY, THOUGH DEWPOINTS IN THE LOWER TO MID 60S HAVE STILL ALLOWED  
FOR PLENTY OF STRATOCUMULUS ON THE BACK SIDE OF THE LOW. FOR OUR  
NORTHWEST, THIS HAS BEEN A COOL DAY IN THE 60S, THOUGH A HIGH IN THE  
LOWER TO MID 70S IS STILL ATTAINABLE IF BREAKS IN THE CLOUDS  
DEVELOP. FARTHER SOUTHEAST, A NORTHWEST BREEZE AT 10 TO 20 MPH HAS  
BEEN BLOWING, WITH TEMPERATURES IN THE MID 70S TO LOWER 80S.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH WEDNESDAY)  
ISSUED AT 246 PM CDT TUE AUG 21 2018  
 
TONIGHT SHOULD BE A DRY NIGHT, IF YOU BELIEVE ALL MODELS EXCEPT THE  
HRRR. THE HRRR BRINGS A FEW CELLS THROUGH THE HEART OF THE AREA  
AROUND 7 PM, AND THAT SEEMS OVERDONE, BUT ENOUGH TO HAVE US IN THE  
10% RANGE ON POPS EARLY THIS EVENING. OTHERWISE, EXPECT SKIES TO  
SLOWLY THIN TO CLEAR THIS EVENING, WITH SHALLOW MOISTURE DEPOSITING  
OUT AS DEW OVERNIGHT. THAT WILL ALLOW THE DEWPOINTS TO FALL TO THE  
50S, CLOSELY FOLLOWED BY THE TEMPERATURE. LOWS IN THE LOWER 50S  
NORTH TO UPPER 50S FAR SOUTH WILL BE FORECAST FOR LOWS. I DO NOT  
THINK FOG WILL BE WIDESPREAD, AS WE KEEP A NORTHWEST WIND AROUND 5  
TO 8 MPH TONIGHT.  
 
WEDNESDAY APPEARS QUIET, AND VERY PLEASANT, WITH LOW DEWPOINTS AND  
HIGHS BACK IN THE UPPER 70S TO LOWER 80S. THIS IS FORECAST BY ALL  
GUIDANCE AS THE HIGH PRESSURE MOVES OVER THE REGION.  
 
ERVIN  
   
LONG TERM
 
(WEDNESDAY NIGHT THROUGH TUESDAY)  
ISSUED AT 246 PM CDT TUE AUG 21 2018  
 
THREE MAIN FEATURES IN THE LONG TERM PERIOD TO DISCUSS. FIRST, THE  
BEGINNING OF WEEK INTO FRIDAY WILL FEATURE TEMPERATURES AND  
DEWPOINTS MUCH MORE LIKE SEPTEMBER THAN AUGUST. THE NEXT, A RATHER  
POTENT UPPER LEVEL TROUGH IS FORECAST TO MOVE THROUGH THE FLOW  
ACROSS THE AREA. IT HAS BEEN A WHILE SINCE DECENT VORTICITY  
ADVECTION WAS FORECAST FOR THE AREA. AFTER THIS SYSTEM MOVES  
THROUGH THE AREA, WE WILL RETURN TO HOT AND HUMID CONDITIONS FOR THE  
WEEKEND INTO NEXT WEEK. WE ARE DEFINITELY NOT DONE WITH SUMMER.  
 
OVERALL QUIET WEATHER IS EXPECTED AS NORTHWEST FLOW REMAINS ACROSS  
THE AREA THROUGH THE END OF THE WEEK. FRIDAY, LARGESCALE FLOW TURNS  
SOUTHWEST AND INDUCES MOISTURE RETURN AHEAD OF AN H5 WAVE. THIS  
WILL OCCUR AT THE HEAT OF PEAK HEATING ACROSS CENTRAL IOWA. MODEL  
GUIDANCE SUGGESTS CONVECTION WILL FIRE ACROSS THIS AREA AND MOVE TO  
THE EAST INTO OUR AREA. DEEP LAYER SHEAR WILL BE SUFFICIENT FOR  
ORGANIZED CONVECTION AND LIKELY STRONG AND EVEN SEVERE WEATHER IF  
STORMS DEVELOP. ALONG WITH THIS THREAT, DECENT RAIN ACROSS THE CWA  
LOOKS LIKELY AS WELL. THIS SYSTEM WILL BE LIKELY THE MAIN FORECAST  
CONCERN THROUGH THE PERIOD.  
 
THIS WEEKEND A RETURN TO HOT AND HUMID TEMPS IS EXPECTED.  
CONDITIONS MAY WARRANT HEAT ADVISORIES.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING)  
ISSUED AT 609 PM CDT TUE AUG 21 2018  
 
LEFTOVER MVFR CIGS FROM A DEPARTING STORM SYSTEM WILL DIMINISH  
THIS EVENING, ALLOWING VFR CONDITIONS TO PREVAIL FOR THE REMAINDER  
OF THE TAF PERIOD AS HIGH PRESSURE BUILDS ACROSS THE MIDWEST.  
GUSTY NORTHWEST WINDS AROUND 10-15 KTS WILL DECREASE TO 5-10 KTS  
AS THE EVENING PROGRESSES.  
 

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

 
 

 
 
SYNOPSIS...ERVIN  
SHORT TERM...ERVIN  
LONG TERM...GIBBS  
AVIATION...SPECK  
 
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