585  
FXUS63 KDVN 250004  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
704 PM CDT WED MAY 24 2017  
   
..00Z AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 308 PM CDT WED MAY 24 2017  
 
UPPER LEVEL LOW PRESSURE/COLD POCKET HAS SHIFTED INTO CENTRAL MO  
WITH SPOKES OF VORTICITY ROTATING CYCLONICALLY AROUND THE CENTER  
OF THE LOW. IN THE DVN CWA, THE MORE CONCENTRATED AREA OF  
INSTABILITY SHOWERS AND EVEN A COUPLE OF BRIEF LIGHTNING STRIKES  
HAVE BEEN IN OUR SOUTHERN CWA. THIS IS WHERE TEMPERATURES MANAGED  
TO PUSH INTO THE MID 60S (THANKS TO SOME SUN) ALLOWING FOR SBCAPES  
OF 250 J/KG. HOWEVER, SHEAR IS VERY WEAK AND SO ARE MID LEVEL  
LAPSE RATES. THERE ARE ALSO A FEW WEAKENING SHOWERS NOTED ON  
DOPPLER RADAR IN NW IL AND EXTREME EASTERN IA. THESE SHOWERS ARE  
MOVING SOUTHWEST TO SOUTH AT ABOUT 15 TO 20 MPH. IN OUR NORTHERN  
COUNTIES, WHERE CLOUDS HAVE BEEN MORE PERSISTENT, TEMPERATURES  
WERE ONLY IN THE MID TO UPPER 50S EARLY THIS AFTERNOON. VERY COOL  
FOR LATE MAY CONCERNING NORMAL HIGHS ARE IN THE 70S.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH THURSDAY)  
ISSUED AT 308 PM CDT WED MAY 24 2017  
 
FORECAST FOCUS ON FOG POTENTIAL TONIGHT THEN PLENTY OF SUN AND  
WARMER TEMPERATURES ON THURSDAY.  
 
TONIGHT: WITH LOSS OF HEATING ANY LINGERING SHOWERS SHOULD HAVE  
ENDED BY AROUND 7 PM OR SO, BUT BASICALLY WE HAVE A DRY FORECAST  
FOR TONIGHT. THIS TREND IS INDICATED ON ESRL HRRR/HRRR/NAMNEST  
MODELS. HOWEVER, THE CHALLENGE WILL BE ANY FOG DEVELOPMENT LATER  
TONIGHT AND HOW DENSE OR WIDESPREAD IT MAY BECOME. HIGH PRESSURE  
RIDGE WILL BE MOVING INTO OUR WESTERN COUNTIES AFTER MIDNIGHT,  
WITH CLEARING SKIES EXPECTED. WINDS WILL ALSO BECOME RATHER LIGHT  
AND MODELS SUGGEST PLENTY OF LOW LEVEL MOISTURE, BENEATH A  
SOMEWHAT STRENGTHENING LOW LEVEL INVERSION. WILL MENTION "AREAS OF  
FOG" IN OUR WEST WHERE SKIES SHOULD CLEAR AND "PATCHY FOG" IN OUR  
EAST WHERE CLOUDS SHOULD LINGER THE LONGEST. WITH LOW CONFIDENCE  
AT THIS TIME I WILL PASS CONCERNS TO THE UPCOMING SHIFTS TO  
MONITOR TRENDS IF A HEADLINE IS NEEDED. MINIMUM TEMPERATURES WILL  
RANGE FROM THE MID 40S TO LOWER 50S.  
 
THURSDAY: OTHER THAN EARLY TO MID MORNING FOG UNTIL THE INVERSION  
BREAKS, SKIES SHOULD BE OR BECOME MOSTLY SUNNY AND A DELIGHTFUL  
DAY IS EXPECTED. HIGH PRESSURE RIDGE WILL BE OVER THE CWA WITH  
LIGHT WINDS ALONG WITH WARMER TEMPERATURES. AFTERNOON HIGHS SHOULD  
PUSH INTO THE LOWER 70S AT MOST LOCATIONS.  
   
LONG TERM
 
(THURSDAY NIGHT THROUGH WEDNESDAY)  
ISSUED AT 308 PM CDT WED MAY 24 2017  
 
THE LONG TERM WILL FEATURE MOSTLY UNSETTLED WEATHER FOR THE REGION  
THROUGH MEMORIAL DAY WEEKEND, ALONG WITH TEMPERATURES MAINLY BELOW  
NORMAL.  
 
THURSDAY NIGHT...WHILE MUCH OF THE NIGHT WILL REMAIN DRY, CHANCES  
FOR RAIN SHOWERS WILL GRADUALLY INCREASE FROM SOUTHWEST TO NORTHEAST  
EARLY FRIDAY MORNING. FORECAST INSTABILITY REMAINS LOW, SO NOT  
EXPECTING MUCH, IF ANY, THUNDERSTORM CHANCES.  
 
FRIDAY...MODELS CONTINUE TO REMAIN UNCERTAIN ON PRECIPITATION  
PLACEMENT, BUT OVERALL CONFIDENCE IS HIGH THAT SHOWERS AND  
THUNDERSTORMS WILL OCCUR ACROSS THE REGION DURING THE DAY AS A MID-  
LEVEL SHORTWAVE MOVES ACROSS THE MID MISSISSIPPI VALLEY. HAVE  
DECIDED TO FOLLOW THE BLEND AT THIS TIME, WHICH APPEARS TO BE  
FOLLOWING THE LEAD OF THE NAM AND CANDIAN IN KEEPING HIGHER AMOUNTS  
TO THE SOUTH AND EAST OF THE QUAD CITIES. THERE IS A LOW POTENTIAL  
OF SEVERE WEATHER ACROSS THE SOUTHERN CWA WHERE MODEST INSTABILITY  
AND SHEAR WILL BE PRESENT, BUT THESE VALUES HAVE BEEN CONSISTENT IN  
THE LATEST GUIDANCE.  
 
FOR FRIDAY NIGHT, LOOK FOR A BRIEF BREAK IN PRECIPITATION COVERAGE  
AS A WEAK RIDGE OF HIGH PRESSURE BUILDS ACROSS THE REGION.  
 
SATURDAY...A TROUGH WILL MOVE INTO THE GREAT PLAINS/MIDWEST SATURDAY  
MORNING, AND WILL INCREASE OUR POTENTIAL FOR SHOWERS AND  
THUNDERSTORMS BEGINNING SATURDAY AFTERNOON. THE LATEST GLOBAL MODELS  
CONTINUE TO KEEP THE WARM FRONT JUST SOUTH OF OUR CWA, AND ARE IN  
AGREEMENT OF PLACING THE HIGHER QPF TOWARDS THE I-70 CORRIDOR. THE  
POTENTIAL FOR SEVERE WEATHER REMAINS LOW AT THIS TIME, AND WOULD  
MAINLY BE OVER THE SOUTHERN CWA WHERE HIGHER INSTABILITY AND SHEAR  
WILL BE PRESENT.  
 
SUNDAY THROUGH TUESDAY...A PATTERN SIMILAR TO WHAT WE HAVE  
EXPERIENCED OVER THE PAST FEW DAYS LOOKS TO BE ON TAP FROM THE END  
OF MEMORIAL DAY WEEKEND INTO MID NEXT WEEK. ALL MODELS ARE GENERALLY  
IN AGREEMENT OF AN UPPER LEVEL LOW IN PLACE JUST NORTH OF THE GREAT  
LAKES, WHICH WILL KEEP NORTHWESTERLY FLOW OVER THE REGION. EXPECT A  
CHANCE OF PRECIPITATION EACH DAY AS POCKETS OF MOISTURE AND WEAK  
SHORTWAVES ROUND THE LOW, WITH HIGH TEMPERATURES NEAR OR SLIGHTLY  
BELOW NORMAL.  
 
WEDNESDAY...OVERALL, GOOD AGREEMENT IS IN PLACE ON SURFACE HIGH  
PRESSURE BUILDING ACROSS THE MISSISSIPPI RIVER VALLEY, WITH DRY  
CONDITIONS AND TEMPERATURES CLIMBING TO NEAR NORMAL.  
 

 
   
AVIATION
 
(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING)  
ISSUED AT 652 PM CDT WED MAY 24 2017  
 
CHALLENGING FORECAST WITH RESPECT TO CLOUD COVER. UPSTREAM WESTERN  
PLAINS UPPER RIDGE WILL BUILD EASTWARD AND HAVE A SUBSIDENCE  
SCOURING EFFECT ON THE MORE CELLULAR CU TO THE WEST AND LOCALLY AS  
WELL. BUT THIS PROCESS WILL BATTLE SOUTHWESTERN GRT LKS UPPER LOW  
WHICH WILL STILL TRY AND WHIRL A MORE EXTENSIVE MVFR STRATOCU  
DECK CURRENTLY ACRS WI DOWN ACRS THE LOCAL AREA OVERNIGHT AND  
INTO EARLY THU MORNING. THE DBQ AND MLI SITES WILL BE ESPECIALLY  
PRONE TO THIS DECK COMING IN AFTER MIDNIGHT AFTER A POSSIBLE  
TEMPORARY MID EVENING CLEARING. BESIDES THE CLOUDS, ANY CLEAR  
SPOTS OR CLEAR SKY TRENDS COMBINED WITH LIGHT WINDS OF 5 KTS OR  
LESS, MAY FOSTER AREAS OF FOG, SOME POSSIBLY DENSE, LATE TONIGHT  
INTO EARLY THU MORNING. RATHER LIGHT AND VARIABLE WINDS ON THU  
UNDER PASSING RIDGE AXIS, ALONG WITH AMBIENT SCTRD-BKN CU OF  
2000-3000 FT AGL LIFTING TO 4000 FT BY AFTERNOON. ..12..  
 

 
   
HYDROLOGY
 
 
ISSUED AT 1220 PM CDT WED MAY 24 2017  
 
CONFIDENCE HAS INCREASED THIS MORNING ALONG THE MISSISSIPPI FROM  
CAMANCHE TO KEITHSBURG REACHING FLOOD STAGE, AND THUS HAVE  
UPGRADED TO FLOOD WARNINGS FROM THE WATCHES ALREADY IN EFFECT. IT  
SHOULD BE NOTED THAT FORECAST CRESTS WILL LIKELY CHANGE AT THESE  
LOCATIONS, SO THESE WILL NEED TO BE MONITORED WITH LATER FORECASTS  
AND STATEMENTS. FOR SPECIFIC HEIGHT FORECASTS, PLEASE SEE THAT  
LATEST FLOOD WARNING STATEMENTS. FLOOD WARNINGS CONTINUE FOR BOTH  
DUBUQUE LOCATIONS, GLADSTONE AND BURLINGTON.  
 
HAVE DECIDED TO GO WITH FLOOD WATCHES FOR BELLEVUE, FULTON AND  
GREGORY LANDING THIS TIME AS CONFIDENCE OF THESE LOCATIONS REACHING  
FLOOD STAGE REMAINS LOW. THAT BEING SAID, THESE 3 LOCATIONS WILL BE  
MONITORED, WITH A FINAL DECISION OF FLOOD WARNING ISSUANCE  
WITH BELLEVUE AND FULTON OCCURRING WITHIN THE NEXT FEW DAYS.  
 

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

 
 

 
 
SYNOPSIS...HAASE  
SHORT TERM...HAASE  
LONG TERM...SPECK  
AVIATION...12  
HYDROLOGY...SPECK  
 
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