402
FXUS63 KDVN 291855
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
155 PM CDT SAT AUG 29 2026
KEY MESSAGES
- HEAT AND HUMIDITY WILL BUILD ACROSS THE AREA FOR AT LEAST THE FIRST
HALF OF NEXT WEEK. HEAT INDEX VALUES ARE EXPECTED TO RISE TO
THE MIDDLE 90S TO AROUND 100 DEGREES, HIGHEST FOR AREAS SOUTH
OF I- 80. THIS IS DEPENDENT ON IF SHOWERS/STORMS DEVELOP,
WHICH WOULD COOL TEMPERATURES.
- THERE IS POTENTIAL FOR ACTIVE WEATHER AT TIMES, DEPENDING ON
THE WHERE THE EDGE OF THE HEAT DOME SETTLES.
SHORT TERM /THROUGH SUNDAY/
ISSUED AT 147 PM CDT SAT AUG 29 2026
THE AREA OF SHOWERS AND ISOLATED THUNDERSTORMS FROM THIS MORNING
WILL CONTINUE TO SLOWLY DISSIPATE THIS AFTERNOON AS IT MAKES IT WAY
EASTWARD, GIVING WAY FOR DRY CONDITIONS LATE THIS AFTERNOON AND
EVENING ACROSS THE AREA. WITH THE PRECIPITATION AND CLOUD COVER,
TEMPERATURES THIS AFTERNOON HAVE BEEN SLIGHTLY COOLER ACROSS OUR
NORTHEAST, WITH HIGHS IN THE MIDDLE 70S OVER NORTHWEST ILLINOIS AND
ADJACENT AREAS OF NORTHEAST IOWA, TO THE MIDDLE/UPPER 80S TOWARDS
NORTHEAST MISSOURI, SOUTHEAST IOWA, AND WEST-CENTRAL ILLINOIS.
DRY CONDITIONS ARE EXPECTED THIS EVENING BEFORE AN AREA OF SHOWERS
AND ISOLATED THUNDERSTORMS REDEVELOP LATE TONIGHT INTO SUNDAY
MORNING AHEAD OF A 35 TO 45 KNOT SOUTH-SOUTHWESTERLY LOW-LEVEL JET.
COMPOSITE REFLECTIVITY PAINTBALL FIELDS FROM THE 29.12Z HREF AND
REFS ENSEMBLES SUGGESTS ISOLATED TO SCATTERED SHOWERS, WITH ISOLATED
STORMS, LATE TONIGHT INTO SUNDAY MORNING, MAINLY FOR OUR EASTERN AND
SOUTHERN PORTIONS OF THE AREA (20-40% CHANCES). WITH MEAGER MUCAPE
VALUES (<500 J/KG PER THE HREF), THUNDERSTORM POTENTIAL APPEARS TO
BE QUITE LOW.
THE REST OF THE DAY SUNDAY WILL BE NOTICEABLY WARMER AND MORE HUMID
AS MID-LEVEL RIDGING AND A HEAT DOME BUILDS OVER THE CENTRAL CONUS.
LREF ENSEMBLE CLUSTER ANALYSIS IS IN VERY GOOD AGREEMENT ON THIS
OCCURRING, WITH 500 MB HEIGHTS OF 594 DECAMETERS OVER THE SOUTHERN
PLAINS/SOUTHERN MS RIVER VALLEY REGIONS. HIGH TEMPERATURES ON SUNDAY
ARE EXPECTED TO WARM TO THE UPPER 80S TO LOWER 90S OVER MOST OF THE
AREA, WARMEST OVER OUR SOUTHERN AREAS. HOWEVER, AS A WEAK MID-LEVEL
SHORTWAVE IS PROGGED TO SWEEP THROUGH THE AREA, THIS COULD GENERATE
ADDITIONAL SHOWERS AND STORM CHANCES ALONG AND NORTH OF HIGHWAY 30,
WHICH COULD KEEP TEMPERATURES RELATIVELY COOLER THERE. SO, SOME
UNCERTAINTY EXISTS ON EXACTLY HOW WARM WE WILL GET SUNDAY FOR THESE
AREAS.
LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/
ISSUED AT 147 PM CDT SAT AUG 29 2026
THE MAIN FOCUS FOR THE LONG-TERM FORECAST PERIOD CONTINUES TO BE ON
BUILDING HEAT AND HUMIDITY, ESPECIALLY FOR MONDAY THROUGH AT LEAST
WEDNESDAY BEFORE RELATIVELY COOLER CONDITIONS RETURN BY THE END OF
THE WEEK. FOR AREAS THAT AVOID ANY PRECIPITATION DURING THIS PERIOD,
CONFIDENCE IS HIGHER FOR VERY WARM AND MUGGY CONDITIONS. THE LATEST
ECMWF EFI/SHIFT OF TAILS VALUES FOR HIGH TEMPERATURES MONDAY THROUGH
WEDNESDAY ARE IN EXCESS OF 0.9 (EVEN SOME VALUES OVER 0.95 IN
ISOLATED SPOTS), ALONG WITH SHIFT OF TAILS VALUES AROUND 1. THIS
SUGGESTS HIGH CONFIDENCE IN ANOMALOUSLY WARM HIGH TEMPERATURES,
ALTHOUGH NOT EXTREME VALUES BASED ON THE LOWER SHIFT OF TAILS. IN
TERMS OF HEAT HEADLINES, WE WILL NEED TO WATCH THIS CLOSELY, GIVEN
THE LREF ENSEMBLE EXCEEDANCE PROBABILITIES OF HEAT INDICES OF 100
DEGREE OR WARMER IS AROUND 30 TO 50% FOR AREAS ALONG AND SOUTH OF
HIGHWAY 92 FOR WEDNESDAY AND THURSDAY. THE PROBABILITIES OF HEAT
INDICES OF 95 DEGREE OR WARMER GOES UP DRASTICALLY, TO AROUND 60 TO
90% OVER MOST OF OUR FORECAST AREA. ADDITIONALLY, OVERNIGHT LOWS
MIGHT NOT DIP BELOW 75 DEGREES MONDAY NIGHT THROUGH WEDNESDAY NIGHT,
SO THIS WOULD CONTINUE STRESS FROM THE HEAT - EVEN AT NIGHT. THERE
IS POTENTIAL FOR SOME RECORD WARM LOW TEMPERATURES DURING THIS
PERIOD. SEE THE CLIMATE SECTION BELOW FOR THE CURRENT RECORDS. WE
WILL HOLD OFF ON HEADLINES FOR NOW, BUT HEAT ADVISORIES MAY BE
NEEDED NEXT WEEK.
WITH ALL OF THIS SAID, IT BEARS REPEATING THAT ANY SHOWERS OR STORMS
THAT DEVELOP WILL HELP TO LIMIT TEMPERATURES, AND THEREFORE, HEAT
INDICES. ULTIMATELY, THIS APPEARS MOST LIKELY FOR AREAS ALONG AND
NORTH OF HIGHWAY 30, WHERE BOTH NBM AND LREF ENSEMBLE PROBABILITIES
OF MEASURABLE RAINFALL ARE 40 TO 60%. IN TERMS OF STRONG TO SEVERE
STORMS, THERE ARE SOME SIGNALS IN THE VARIOUS MACHINE-LEARNING
SEVERE PROBS FOR AT LEAST A LIMITED POTENTIAL ON WEDNESDAY AND
THURSDAY AS THE MID-LEVEL RIDGE BECOMES MORE ZONAL FOR A TIME AND A
WEAK COLD FRONT SWEEPS THROUGH THE AREA DURING THAT TIME WITH
APPRECIABLE INSTABILITY. SOMETHING FOR US TO KEEP AN EYE ON, BUT
WITH IT BEING FURTHER OUT, CONFIDENCE ISN'T PARTICULARLY HIGH ON
SEVERE WEATHER AT THIS TIME.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1232 PM CDT SAT AUG 29 2026
LARGELY VFR CONDITIONS WERE SEEN ACROSS THE AREA, UNDER HIGH-
LEVEL CLOUDS AND AN AREA OF SHOWERS AROUND CID NORTHEAST
TOWARDS DBQ. THE SHOWERS HAVE BEEN SLOWLY DISSIPATING OVER THE
LAST HOUR OR SO, AND THUS, VISIBILITIES HAVEN'T GONE DOWN AS
MUCH AS EXPECTED. AT WORST, HIGH-END MVFR VISIBILITY REDUCTIONS
ARE POSSIBLE UNDER THE SHOWERS. OTHERWISE, AS THE SHOWERS
DISSIPATE, SOUTHERLY WINDS SHOULD STRENGTHEN THIS AFTERNOON,
GUSTING TO AROUND 25 KNOTS. AS THE SURFACE GUSTS DIMINISH THIS
EVENING, A PERIOD OF LOW-LEVEL WIND SHEAR IS EXPECTED AREA-WIDE
AS A 35 TO 45 KNOT SOUTH-SOUTHWESTERLY LOW-LEVEL JET DEVELOPS.
SOME SHOWERS AND ISOLATED THUNDERSTORMS ARE POSSIBLE ONCE AGAIN
AROUND OR AFTER SUNRISE, BUT CONFIDENCE IS PRETTY LOW ON THE
EXACT COVERAGE OF THIS ACTIVITY, SO USED PROB30 GROUPS TO
HIGHLIGHT THE MORE LIKELY TIMING.
CLIMATE
ISSUED AT 139 PM CDT FRI AUG 28 2026
RECORD WARM LOW TEMPERATURES:
AUGUST 31:
KDBQ: 74/2000
KMLI: 75/2000
SEPTEMBER 1:
KDBQ: 73/1937
KMLI: 75/1913
SEPTEMBER 2:
KDBQ: 74/2011
KMLI: 77/1913
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...SCHULTZ
LONG TERM...SCHULTZ
AVIATION...SCHULTZ
CLIMATE...GROSS
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