461  
FXUS63 KDVN 140553  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
1253 AM CDT WED APR 14 2021  
   
..06Z AVIATION UPDATE
 
 
   
UPDATE
 
 
ISSUED AT 830 PM CDT TUE APR 13 2021  
 
HAVE EXPANDED THE FROST ADVISORY TO INCLUDE THE I-80 CORRIDOR.  
 
LATEST SATELLITE TRENDS SHOW THE STRATUS INTO NORTHERN IOWA MOVING  
MORE LATITUDINAL THAN LONGITUDINAL, AND WOULD SUPPORT SOME OF THE  
RECENT GUIDANCE IN KEEPING THE I-80 CORRIDOR, WHICH HAS SOME  
SUSCEPTIBLE VEGETATION, LARGELY ABSENT OF THIS THERMALLY  
IMPACTFUL CLOUDINESS. SOME CIRRUS WILL BE PRESENT, BUT SATELLITE  
SHOWS THIS TO BE RATHER THIN AND SHOULD BE LIMITED IN IMPACTS TO  
TEMPERATURES. WITH 850 MB TEMPERATURES PROGGED BACK DOWN TO AROUND  
-5C TO -6C TOMORROW MORNING, ANTICIPATE LOWS NEAR TO A BIT BELOW  
THOSE FROM THIS MORNING IN MOST AREAS AND AROUND 30-36F. FAR  
NORTHERN SECTIONS, ESPECIALLY IN EASTERN IOWA, LOWS ARE A BIT  
TRICKY AS THE STRATUS MAY EVENTUALLY WORK SOUTHWARD AND OFFER  
PERIODIC BOUTS OF CLOUDINESS. THUS, IT LOOKS LIKE THERE IS THE  
POTENTIAL TO BE A BIT WARMER THAN FORECAST INTO PORTIONS OF  
NORTHEAST IOWA.  
 

 
   
SYNOPSIS
 
 
ISSUED AT 244 PM CDT TUE APR 13 2021  
 
ANOTHER GREAT DAY WAS UNFOLDING ACROSS ALL OF EASTERN IOWA,  
NORTHWEST ILLINOIS AND FAR NORTHEAST MISSOURI, WITH THE AREA UNDER  
INFLUENCE FROM HIGH PRESSURE RIDGING EXTENDING FROM THE CENTRAL  
GREAT PLAINS INTO THE OHIO RIVER VALLEY. SKIES FEATURED A MIX OF SUN  
AND CLOUDS, WITH SOMEWHAT COOL TEMPERATURES ATYPICAL FOR MID-APRIL.  
VALUES AS OF 2 PM RANGED FROM 47 IN DUBUQUE, TO 57 IN KEOKUK.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH WEDNESDAY)  
ISSUED AT 244 PM CDT TUE APR 13 2021  
 
KEY MESSAGES:  
 
1) PATCHY TO AREAS OF FROST TONIGHT, WITH IMPACTS LIKELY MAINLY  
SOUTH OF I-80.  
 
2) A CHANCE FOR PM SPRINKLES WEDNESDAY, BUT MOST WILL REMAIN DRY.  
COOL TEMPERATURES CONTINUE.  
 
HIGH PRESSURE WILL REMAIN IN CONTROL OF OUR WEATHER FOR THROUGH  
WEDNESDAY, MEANING QUIET WEATHER WITH MAINLY DRY CONDTIONS ARE  
EXPECTED. THE ONLY EXCEPTION WILL AREAS OF EASTERN IOWA AND  
NORTHWEST ILLINOIS MAINLY NORTH OF I-80 WEDNESDAY AFTERNOON, WHERE  
THERE WILL BE A CHANCE OF SPRINKLES. SEVERAL CAMS INCLUDING THE  
NAMNEST AND HRRR ARE ON BOARD WITH THIS IDEA AS AN AREA OF CVA  
ROTATES AROUND THE SOUTHERN PORTION OF A 500 HPA LOW CENTERED OVER  
THE GREAT LAKES. THESE WILL BE SCATTERED IN NATURE, WITH MUCH OF  
LIKELY REMAINING DRY THROUGH THE DAY.  
 
THE MORE PRESSING CONCERN WILL BE THE THREAT OF FROST TONIGHT, WHICH  
LOOKS LIKELY WITH LIGHT WINDS, CLEAR SKIES AND A COOL AIR MASS IN  
PLACE ACROSS PARTS OF THE AREA. AFTER COORDINATING WITH  
SURROUNDING OFFICES, WENT AHEAD AND ISSUED A FROST ADVISORY FOR  
COUNTIES ALONG AND SOUTH OF HWY 34 IN SOUTHEAST IOWA, WEST CENTRAL  
ILLINOIS AND FAR NORTHEAST MISSOURI. THIS AREA IS MOST  
SUSCEPTIBLE ACROSS THE CWA WITH REGARDS TO VEGETATION.  
TEMPERATURES ARE EXPECTED TO FALL INTO THE LOW TO MID 30S HERE.  
 
ELSEWHERE, TEMPERATURES WILL BE COLD WITH VALUES DROPPING TO NEAR 30  
ALONG THE HWY 20 CORRIDOR. WITH NO SUSCEPTIBLE VEGETATION HERE  
DID NOT GO AHEAD WITH FROST/FREEZE HEADLINES. HIGHS TOMORROW WILL  
CONTINUE TO BE COOL WITH VALUES IN THE UPPER 40S/LOW 50S.  
   
LONG TERM
 
(WEDNESDAY NIGHT THROUGH TUESDAY)  
ISSUED AT 244 PM CDT TUE APR 13 2021  
 
KEY MESSAGES:  
 
1) BELOW NORMAL TEMPERATURES CONTINUE.  
 
2) MAINLY DRY THROUGH THE WEEKEND; PRECIPITATION CHANCES INCREASE  
NEXT WEEK.  
 
3) POTENTIAL FOR FROST AGAIN WEDNESDAY NIGHT/THURSDAY MORNING.  
 
WEDNESDAY NIGHT AND THURSDAY MORNING WILL ONCE AGAIN BE MONITORED  
FOR FROST/FREEZE POTENTIAL AS ANOTHER NIGHT OF COLD TEMPERATURES IS  
EXPECTED. WHILE TEMPERATURES ARE FORECAST TO NOT BE AS COLD AS  
TONIGHT, VALUES IN THE LOW 30S WILL BE MORE WIDESPREAD. WILL MONITOR  
FOR POTENTIAL FOR MORE HEADLINES TOMORROW.  
 
OTHERWISE, MOST OF THE LONG TERM PERIOD WILL FEATURE MAINLY DRY  
CONDITIONS AND CONTINUED COOL TEMPERATURES WITH THE DOMINANT FLOW  
PATTERN EXPECTED TO REMAIN OUT OF THE NORTHWEST. DAILY HIGHS IN THE  
50S TO NEAR 60 ARE EXPECTED, WITH OVERNIGHT LOWS IN THE 30S TO LOW  
40S.  
 
CHANCES FOR PRECIPITATION ARE MAINLY FAVORED FRIDAY NIGHT AND  
SATURDAY AS A WEAK SHORTWAVE PASSES ACROSS THE AREA TO THE SOUTH.  
MODELS ARE IN DISAGREEMENT OF INTENSITY, WITH THE GFS SUGGESTING  
MORE OF A MOISTURE DRAW, STRONGER LIFT AND THUS A HIGHER QPF FOR OUR  
SOUTHEAST IOWA, WEST CENTRAL ILLINOIS AND NORTHEAST MISSOURI  
COUNTIES. HOWEVER, THIS LOOKS TO BE THE OUTLIER OF GUIDANCE, SO WILL  
PLAY MORE ON THE CONSERVATIVE END WITH JUST A SLIGHT CHANCE TO  
CHANCE OF POPS. THIS IS FAVORED OVER OUR SOUTHEAST IOWA, WEST  
CENTRAL ILLINOIS AND NORTHEAST MISSOURI COUNTIES.  
 
THERE IS AGREEMENT THAT A COLD FRONT APPROACHING THE AREA WILL BE  
THE DRIVER FOR OUR NEXT CHANCE OF PRECIPITATION, WHICH LOOKS TO BE  
FAVORED NEXT MONDAY/MONDAY NIGHT. NBM HAS INTRODUCED SLIGHT  
CHANCE POPS WITH THIS RUN, AND I THINK THAT'S A GOOD STARTING  
POINT CONSIDERING WE HAVE PLENTY OF TIME FOR THINGS TO GET MORE  
REFINED IN THE GUIDANCE.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT)  
ISSUED AT 1246 AM CDT WED APR 14 2021  
 
VFR CONDITIONS WITH RATHER LIGHT WEST TO NORTHWEST SFC WINDS  
OVERNIGHT, THAT UNTIL TIMING A MVFR BKN OR EVEN OVC STRATOCU DECK  
ROTATING DOWN ACRS MOST OF THE TERMINALS WED MORNING. ONLY BRL  
MAYBE SPARED FROM THE MVFR DECK, AS IT ADVECTS ACRS THE REST OF  
THE TERMINALS FROM MID MORNING THROUGH EARLY AFTERNOON. SOME  
LIFTING OF THE DECK TO LOW VFR LEVELS(ABOVE 3K FT AGL) AT TIMES  
INTO WED EVENING. SOME ISOLATED TO WIDELY SCTRD INSTABILITY  
SHOWERS WILL LOOK TO POP UP IN THE MID TO LATE AFTERNOON PERIOD  
MAINLY ALONG AND NORTH OF HWY 30, BUT COVERAGE UNCERTAINTY  
PRECLUDES TAF MENTION OR EVEN A VCNTY AT THIS TIME. WEST TO  
NORTHWEST SFC WINDS WILL INCREASE AGAIN MID TO LATE WED MORNING  
10-15 KTS WITH HIGHER GUSTS. ..12..  
 

 
   
DVN WATCHES/WARNINGS/ADVISORIES
 
 
IA...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR CEDAR-DES MOINES-  
HENRY IA-IOWA-JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA-MUSCATINE-  
SCOTT-VAN BUREN-WASHINGTON.  
 
IL...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR BUREAU-HANCOCK-  
HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND-  
WARREN.  
 
MO...FROST ADVISORY UNTIL 8 AM CDT THIS MORNING FOR CLARK-SCOTLAND.  
 

 
 

 
 
UPDATE...MCCLURE  
SYNOPSIS...SPECK  
SHORT TERM...SPECK  
LONG TERM...SPECK  
AVIATION...12  
 
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