493  
FXUS63 KDVN 221726  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
1226 PM CDT FRI OCT 22 2021  
   
..AVIATION UPDATE
 
 
   
SYNOPSIS
 
 
ISSUED AT 220 AM CDT FRI OCT 22 2021  
 
LATEST GOES NIGHTTIME MICROPHYSICS IMAGERY EARLY THIS MORNING  
SHOWS PERSISTENT LOW LEVEL STRATUS ACROSS THE SOUTHEAST HALF OF  
THE CWA. 00Z DVN/ILX SOUNDINGS SHOWED A RATHER STRONG INVERSION  
AROUND 900MB TRAPPING THESE CLOUDS. LOOKING FURTHER UPSTREAM, MID  
AND HIGH LEVEL CLOUDS ARE TRACKING SOUTHEAST OUT OF THE NORTHERN  
PLAINS AND INTO SOUTHERN MN AND NORTHERN IA.  
 
2AM SURFACE OBSERVATIONS SHOW TEMPERATURES MAINLY IN THE MIDDLE  
30S ALONG AND NORTH OF A LINE FROM SIGOURNEY, TO CEDAR RAPIDS, TO  
FREEPORT. THIS IS WHERE THERE ARE NO CLOUDS AND WHERE FROST IS  
LIKELY THIS MORNING. ELSEWHERE, TEMPERATURES WERE IN THE 40S  
UNDERNEATH THE STRATUS CLOUDS.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 220 AM CDT FRI OCT 22 2021  
 
FORECAST FOCUS TODAY IS ON CLOUD AND TEMPERATURE TRENDS AND  
CHANCE FOR FROST TONIGHT. NO CHANGE TO FROST HEADLINES FOR THIS  
MORNING.  
 
AN UPPER LEVEL WAVE WILL TRACK EAST ACROSS THE CWA TODAY,  
BRINGING AN INCREASE IN CLOUDS. KEPT THE TREND FROM PREVIOUS  
FORECASTS AND WENT WITH THE LOWER SIDE OF GUIDANCE FOR  
TEMPERATURES. HIGHS IN THE LOW TO MID 50S ARE FORECAST, SIMILAR TO  
WHAT OCCURRED YESTERDAY. LATEST RAP SHOWS ENOUGH LIFT AND  
MOISTURE WITH THE WAVE TO WARRANT ADDING SOME SLIGHT CHANCE  
POPS/SPRINKLES TO THE FORECAST FOR A FEW HOURS IN THE AFTERNOON.  
ANY PRECIPITATION THAT REACHES THE GROUND, WILL BE A FEW  
HUNDREDTHS AT BEST.  
 
CLOUDS WILL BEGIN TO DIMINISH THIS EVENING BEHIND THE PASSAGE OF  
THE AFOREMENTIONED SHORTWAVE, ALONG WITH DECREASING WINDS. THIS  
WILL SET THE STAGE FOR TEMPERATURES DROPPING INTO THE LOW TO MID  
30S OVERNIGHT AND FROST HEADLINES WILL BE NEEDED. WILL LET THE  
DAYSHIFT MAKE THE FINAL CALL ON LOCATION OF HEADLINES ONCE THE  
CURRENT FROST ADVISORY EXPIRES. AT THIS TIME, AREAS ALONG AND  
NORTH OF I-80 WILL HAVE THE BEST CHANCES OF FROST FORMATION EARLY  
SATURDAY. IF WINDS GO COMPLETELY CALM, THERE IS SOME POTENTIAL FOR  
AREAS IN RIVER VALLEYS AND NORTH OF HIGHWAY 20 TO SEE TEMPERATURES  
DROP INTO THE UPPER 20S. WILL PASS THIS CONCERN ON TO THE NEXT  
SHIFT.  
 
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 240 AM CDT FRI OCT 22 2021  
 
KEY MESSAGES:  
 
1. QUIET DAY SATURDAY.  
2. ACTIVE PERIOD FOR REST OF THE LONG TERM.  
3. HEAVY RAIN EVENT FORECAST ALONG THE MO/IA BORDER AND EAST INTO IL  
ON SUNDAY.  
 
DISCUSSION:  
 
PATTERN FAVORS AN ACTIVE STORM TRACK ACROSS OUR AREA THROUGH THE  
LONG TERM. RIDGING ON SATURDAY WILL QUICKLY TURN TO SW WITH RETURN  
FLOW AND STALLED OUT WARM FRONT ACROSS THE SOUTHERN CWA. IMPRESSIVE  
FGEN AND THE UPPER LEVEL LOW MOVING ACROSS THE AREA WILL LEAD TO  
WIDESPREAD RAIN AND SOME THUNDERSTORMS. MORE TEMPORARY RIDGING IS  
EXPECTED MONDAY INTO TUESDAY BEFORE THE FLOW TURNS SOUTHWEST AND AN  
OPEN WAVE MOVES ACROSS THE AREA, BRINGING RAIN TO THE AREA ONCE  
AGAIN.  
 
MAIN FORECAST CHALLENGE TURNS TO SUNDAY'S SYSTEM AND HEAVY RAINFALL.  
GUIDANCE IS IN GOOD AGREEMENT WITH A FILLING LOW MOVING TOWARDS THE  
AREA. A WARM FRONT WILL MAKE IT TO NEAR THE MO/IA BORDER.  
OVERRRUNING PRECIP WILL OVERSPREAD OUR AREA THROUGH THE MORNING.  
SHOWERS AND STORMS ARE EXPECTED, ESPECIALLY NEAR THE WARM FRONT  
ACROSS SOUTHERN IOWA. THE UPPER LEVEL LOW AND SFC LOW MOVE EAST  
ALONG THE FRONT. EVENTUALLY THE WRAP AROUND WILL SLOWLY EXIT THE  
AREA THROUGH MONDAY AS THE CLOSED LOW LUMBERS TO THE EAST.  
 
LOW LEVEL SHEAR IS IMPRESSIVE AND ANY SURFACE BASED STORM THAT COULD  
BE NEAR THE WARM FRONT COULD TAKE ON LOW LEVEL ROTATION. THE MAIN  
QUESTION FOR ANY SEVERE WOULD BE HOW MUCH CAPE IS POSSIBLE. WITH  
THE STALLED SFC FRONT AND ROBUST LIFT OVER THE FRONT, THINK THAT THE  
SEVERE THREAT WILL BE LIMITED AND MAINLY SOUTH OF THE CWA. IF WE  
CAN GET SOME CLEARING, THEN IT IS POSSIBLE FOR SEVERE WEATHER NEAR  
THE SFC FRONT. GFS HAS THIS INTO OUR SOUTHERN CWA BY 30 MILES OR  
SO. ANY CHANGE IN THE PLACEMENT OF THE WARM SECTOR WILL GREATLY  
AFFECT ANY SEVERE THREAT. THE LARGER IMPACT LOOKS TO BE HEAVY RAIN.  
 
SYNOPTIC MODELS SUGGEST 2 TO 3 INCHES OF RAIN WITH THIS EVENT ACROSS  
THE SOUTHERN CWA. LOOKING AT ENSEMBLE GUIDANCE, LOOKS LIKE THIS  
COULD END UP 2 TO 4 INCHES OF RAIN WITH ISOLATED POCKETS OF HIGHER  
AMOUNTS. THE 00Z NAMNEST, UP TO 12Z SUNDAY HAS A 6+ BULLSEYE IN  
SOUTH CENTRAL IOWA. THE SYNOPTIC SETUP POINTS TO A HIGH CONFIDENCE  
HEAVY RAIN EVENT. THE HEAVIEST BAND MAY ONLY FALL IN A 1 TO 2  
COUNTY WIDE BAND AND IS DIFFICULT TO NAIL DOWN AT THE CURRENT TIME.  
LOOKING TO FFG ACROSS THIS AREA, WE COULD SEE SOME ISOLATED FLASH  
FLOODING. LATER FORECASTS CAN REFINE TOTALS AND AREAS WHERE THE  
HEAVIEST IS EXPECTED. WPC HAS A SMALL SLIGHT RISK FOR EXCESSIVE  
RAINFALL. FURTHER NORTH HALF TO 1.5 INCHES OF RAIN IS EXPECTED  
ACROSS THE REST OF THE CWA.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)  
ISSUED AT 1225 PM CDT FRI OCT 22 2021  
 
SURFACE HIGH PRESSURE WILL BRING VFR WEATHER WITH GOOD VISIBILITY  
AND SOME PASSING MID LEVEL CLOUDS THROUGH THE PERIOD. WINDS WILL  
REMAIN NORTHWESTERLY AROUND 3-8 KTS.  
 

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

 
 

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