958  
FXUS63 KDVN 211111  
AFDDVN  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE QUAD CITIES IA IL  
611 AM CDT FRI JUN 21 2024  
   
KEY MESSAGES
 
 
- ANOTHER HOT DAY EXPECTED TODAY, WITH HIGHS IN THE LOWER 90S ALONG  
AND SOUTH OF HIGHWAY 30  
 
- INCREASING CHANCES (20 TO 50%) OF SHOWERS AND STORMS AFTER  
MIDNIGHT TONIGHT, WITH AN OUTSIDE CHANCE OF A STRONG STORM  
 
- MORE ROBUST THUNDERSTORMS ARE EXPECTED SATURDAY AFTERNOON AND  
EVENING, WITH SOME STRONG TO SEVERE STORMS POSSIBLE  
 
- GENERALLY DRY CONDITIONS RETURN FOR SUNDAY THROUGH THURSDAY,  
WITH ANOTHER ROUND OF CONVECTION TUESDAY AND TUESDAY NIGHT  
 

 
   
SHORT TERM /THROUGH SATURDAY/
 
 
ISSUED AT 356 AM CDT FRI JUN 21 2024  
 
THINGS HAVE CALMED DOWN QUITE A BIT FROM YESTERDAY EVENING'S  
CONVECTION, WITH LARGELY DRY CONDITIONS OBSERVED ACROSS THE AREA. A  
LOW-LEVEL THERMAL INVERSION, WHICH HAS DEVELOPED ACROSS OUR FAR  
NORTHERN AREAS, HAS RESULTED IN A LOW STRATUS DECK, AND SOME AREAS  
OF FOG WILL BE POSSIBLE EARLY THIS MORNING ALONG THE HIGHWAY 20  
CORRIDOR.  
 
THE OVERALL SYNOPTIC PATTERN HASN'T CHANGED A WHOLE LOT OVER THE  
LAST FEW DAY, WITH A LARGE UPPER-LEVEL HIGH ANCHORED OVER THE  
SOUTHERN GREAT PLAINS REGION. WE REMAIN ON THE FAR NORTHERN SIDE OF  
THE UPPER HIGH, WITH A LOW-AMPLITUDE TROUGH DEVELOPING OVER THE  
NORTHWESTERN CONUS AND AN UPPER-LEVEL JET STREAK OVER THE DAKOTAS  
INTO NORTHERN MINNESOTA. THE HEAT DOME CONTINUES TO BE STRONG, WITH  
TEMPERATURES EXPECTED TO WARM TO THE UPPER 80S NORTH AND THE LOWER  
90S SOUTH FOR HIGHS. A WARM FRONTAL ZONE CONTINUES TO BE DRAPED  
ACROSS FAR NORTHERN IOWA INTO SOUTHEASTERN SD, WHERE A LARGE COMPLEX  
OF THUNDERSTORMS HAS DEVELOPED EARLY THIS MORNING, WHICH SHOULD  
TRANSLATE EASTWARD. THIS COMPLEX, PLUS ADDITIONAL CONVECTION  
EXPECTED LATER ON ALONG THE WARM FRONT, COULD GRAZE OUR FAR NORTHERN  
AREAS LATER ON, WHICH WOULD INFLUENCE TEMPERATURES IF THEY MAKE IT  
INTO OUR AREA. HOWEVER, THE CAPE GRADIENT DOES APPEAR TO REMAIN  
NORTH OF US, SO THE CONVECTION IS LIKELY TO REMAIN ANCHORED ALONG IT  
AND STAY AWAY FROM OUR REGION. HUMIDITY TODAY SHOULD BE SLIGHTLY  
LOWER COMPARED TO THE LAST FEW DAYS, SO ALTHOUGH IT WILL BE ANOTHER  
HOT DAY, HEAT INDICES SHOULD REMAIN BELOW 100 DEGREES, PRECLUDING  
THE NEED FOR HEAT HEADLINES.  
 
SHORTWAVE RIDGING WILL BECOME MORE LIKELY IN OUR REGION LATE TONIGHT  
AS MID-LEVEL SHORTWAVE IMPULSES SINK SOUTHWARD. THIS WILL SUPPORT  
INCREASING CHANCES (20 TO 50%) OF SHOWERS AND STORMS. BOTH SHEAR AND  
INSTABILITY APPEARS TO BE PRETTY MEAGER, WITH DEEP-LAYER SHEAR LESS  
THAN 25 KNOTS AND MOST-UNSTABLE CAPE FROM THE HREF LESS THAN 1000  
J/KG, SO MORE LIKELY NON-SEVERE STORMS SHOULD RESULT. STILL, THERE  
IS AN OUTSIDE CHANCE OF A STRONG STORM, AND SPC DOES HAVE A MARGINAL  
RISK, OR LEVEL 1 OF 5, FOR AREAS ALONG AND NORTH OF A FREEPORT, IL  
TO VAN HORNE, IA LINE.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
 
 
ISSUED AT 356 AM CDT FRI JUN 21 2024  
 
AS WE GO THROUGH THE DAY SATURDAY, THE AFOREMENTIONED LOW-AMPLITUDE  
TROUGH OVER THE NORTHWESTERN CONUS GRADUALLY MOVES EASTWARD WITH  
TIME, AND AN ATTENDANT SURFACE COLD FRONT WILL SWEEP THROUGH OUR  
AREA DURING THE AFTERNOON TO EVENING TIME FRAME. INSTABILITY WILL  
INCREASE TO AROUND 1500 TO 2500 J/KG OF SURFACE-BASED CAPE PER THE  
HREF ENSEMBLE MEAN, AND STRENGTHENING MID-LEVEL WESTERLIES AROUND 35  
TO 45 KNOTS WILL RESULT IN DEEP-LAYER SHEAR INCREASING TO 30 TO 40  
KNOTS, SO MORE SUPPORTIVE OF STRONG TO SEVERE CONVECTION. LOW-LEVEL  
SHEAR AND MID-LEVEL LAPSE RATES REMAINS A BIT MORE LIMITED, BUT PWAT  
VALUES NEAR DAILY RECORDS (2+ INCHES) PER THE SPC SOUNDING  
CLIMATOLOGY FOR THE QUAD CITIES AREA SHOULD HELP SUPPORT STRONG,  
DAMAGING WIND GUSTS AS THE MAIN HAZARD, WITH LARGE HAIL AND ISOLATED  
TORNADOES AS SECONDARY THREATS. AS SUCH, SPC HAS EXPANDED THE SLIGHT  
RISK, OR LEVEL 2 OF 5, FOR AREAS ALONG AND NORTHWEST OF A KEOKUK, IA  
TO STERLING, IL LINE, WITH MARGINAL RISK ELSEWHERE. TIMING OF THE  
FRONT REMAINS UNCERTAIN, GIVEN THE DIFFERENCES AMONG THE CAM  
GUIDANCE, BUT CONFIDENCE REMAINS HIGH FOR A SATURDAY AFTERNOON  
ARRIVAL.  
 
AFTER THE FRONT MOVES THROUGH LATE SATURDAY NIGHT, A MUCH MORE  
PLEASANT DAY IS EXPECTED SUNDAY, WITH LOTS OF SUNSHINE AND MORE  
SEASONAL TEMPERATURES AND HUMIDITY. SUNDAY IS DEFINITELY LOOKING  
LIKE THE PICK DAY FOR THE WEEKEND! IN FACT, THE LARGE-SCALE PATTERN  
APPEARS TO SUPPORT A PERIOD OF MOSTLY DRY CONDITIONS THROUGH  
THURSDAY, THANKS TO UPPER-LEVEL RIDGING DEVELOPING OVER THE  
INTERMOUNTAIN WEST STATES AND SURFACE HIGH PRESSURE SETTLING INTO  
THE UPPER MIDWEST. THE ONLY OTHER OPPORTUNITY FOR SHOWERS AND STORMS  
APPEARS TO BE FOR TUESDAY AND TUESDAY NIGHT, AS YET ANOTHER COMPACT  
UPPER-LEVEL TROUGH AND ATTENDANT SURFACE COLD FRONT CROSSES THE  
AREA. THE TIMING OF THE FRONT PER THE LATEST GLOBAL MODELS DOES  
APPEAR TO BE ADVANTAGEOUS FOR MORE STRONG TO SEVERE STORMS,  
ESPECIALLY WITH THE CSU ML SEVERE PROBS SUGGESTING STRONG TO SEVERE  
CONVECTION WITH A HOT AND HUMID AIR MASS AGAIN IN PLACE, SO WE WILL  
NEED TO WATCH TUESDAY AS WELL.  
 

 
   
AVIATION /12Z TAFS THROUGH 12Z SATURDAY/
 
 
ISSUED AT 611 AM CDT FRI JUN 21 2024  
 
MVFR TO LIFR CONDITIONS WERE OBSERVED EARLY IN THE TAF PERIOD AT  
CID AND DBQ, THANKS TO A LOW STRATUS DECK AND FOG DEVELOPMENT.  
THESE CONDITIONS SHOULD IMPROVE FAIRLY QUICKLY AROUND 13Z OR SO,  
BUT IFR CEILINGS SHOULD LINGER FOR A TIME AT DBQ. SOME ISOLATED  
SHOWERS AND STORMS ARE POSSIBLE LATER THIS AFTERNOON AND  
EVENING, BUT CONFIDENCE IS RATHER LOW ON THE COVERAGE DUE TO  
LARGE DIFFERENCES AMONG THE HIGH RESOLUTION MODELS, SO HAVE  
CONTINUED TO USE PROB30 GROUPS TO HIGHLIGHT THE MOST LIKELY  
TIMING. A WIDESPREAD CUMULUS FIELD IS EXPECTED LATE THIS MORNING  
THROUGH THE AFTERNOON, WITH CEILINGS GENERALLY AROUND 4 TO 5  
KFT.  
 

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

 
 

 
 
SHORT TERM...SCHULTZ  
LONG TERM...SCHULTZ  
AVIATION...SCHULTZ  
 
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