413
FXUS63 KDVN 100533
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1233 AM CDT SUN AUG 10 2025
KEY MESSAGES
- ACTIVE WEATHER IS EXPECTED THROUGH THE BEGINNING OF NEXT WEEK
WITH PERIODS OF SHOWERS AND THUNDERSTORMS LIKELY.
- FLASH FLOODING IS THE MAIN CONCERN THROUGH THE NEXT SEVERAL
DAYS WITH A MODERATE RISK (LEVEL 3 OF 4) FOR EXCESSIVE
RAINFALL. THE STRONGEST STORMS COULD PRODUCE TORRENTIAL
RAINFALL RATES BETWEEN 1-3" PER HOUR AND LOCALLY DAMAGING
WINDS.
- WIDESPREAD 2 TO 4 INCHES OF RAIN ARE POSSIBLE THROUGH MONDAY
WITH SOME AREAS RECEIVING HIGHER AMOUNTS.
UPDATE
ISSUED AT 856 PM CDT SAT AUG 9 2025
AFTER A RATHER QUIET EVENING WITH STRONG TO SEVERE STORMS NOT
YET MATERIALIZING THE QUESTION IS WHETHER OR NOT WE WILL SEE
STORMS TONIGHT. MCV TRACKED SOUTH OF THE AREA THIS EVENING
LEADING TO SOME SEVERE REPORTS JUST SOUTH OF THE CWA. BEHIND
THIS MCV SUBSIDENCE WILL LIKELY KEEP THE SOUTH DRY FOR THE FIRST
4 TO 6 HOURS TONIGHT. LOOKING ON THE NIGHTTIME MICROPHYSICS
IMAGERY IT IS CLEAR THAT ELEVATED CONVECTION IS ATTEMPTING TO
FIRE. WE HAVE SEEN THIS ACROSS THE AREA THIS EVENING, A SIGN OF
HOW UNSTABLE WE ARE. DO BELIEVE WHEN THE H85 INCREASES WE WILL
SEE STORMS START TO FIRE. THIS COULD HAPPEN ANYTIME BETWEEN NOW
AND MIDNIGHT. WITH PWATS ABOVE 2 INCHES HEAVY RAIN WILL BECOME
THE MAIN THREAT OVERNIGHT. SO WITH ALL THAT SAID, WE BELIEVE
THAT WE ARE STILL ON TRACK FOR HEAVY RAIN AN FLASH FLOODING.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 207 PM CDT SAT AUG 9 2025
REMNANTS OF THIS MORNINGS CONVECTION CONTINUE TO SLOWLY MOVE
EASTWARD FROM CENTRAL INTO EASTERN IOWA DURING THE MID
AFTERNOON. THIS CONVECTION IS MOVING INTO A VERY UNSTABLE
CONVECTIVE ENVIRONMENT. THE 18Z BALLOON LAUNCH AT DAVENPORT
SHOWS SURFACE BASED CAPE AROUND 5500 J/KG AND MIXED LAYER CAPE
OF AROUND 3500 J/KG. THERE IS SOMEWHAT WEAK 0 TO 6 KM SHEAR
AROUND 20 KNOTS BUT THIS WILL BE AUGMENTED BY A PAIR OF
APPROACHING MCVS MOVING INTO THE AREA FROM THE WEST. RADAR AND
SATELLITE TRENDS SHOW SOME REDEVELOPMENT OF THE CONVECTION TO
OUR WEST AND EAST OF THE MISSISSIPPI RIVER. DEVELOPMENT OF
STORMS IS EXPECTED THROUGH 6 PM THAT WILL MOVE ACROSS THE AREA.
PRECIPITABLE WATER VALUES THIS AFTERNOON ARE AROUND 1.90 INCHES
WITH HEAVY RAINFALL POSSIBLE WITH ANY OF THESE STORMS. SEVERE
STORMS ARE POSSIBLE WITH THIS ROUND OF STORMS GIVEN STEEPENING
LAPSE RATES AND VERY UNSTABLE AIR WITH DAMAGING WINDS BEING THE
MAIN THREATS.
AFTER THIS AFTERNOONS LINE OF STORMS INTO THE EARLY EVENING, A
BREAK IS EXPECTED BEFORE ANOTHER LINE IS FORECAST TO DEVELOP TO
OUR WEST AND MOVE ACROSS THE AREA WITH RECURRING ROUNDS OF
SHOWERS AND THUNDERSTORMS EXPECTED BEHIND THIS LINE. THE 12Z
HREF 1 AND 3 HOUR PROBABILITY MATCH MEAN (PPM) PRECIPITATION OF
1 TO 3 INCHES OF RAIN POSSIBLE THAT REPEATED ROUNDS OF RAIN
COULD LEAD TO FLASH FLOODING ACROSS THE AREA. THE FLOOD WATCH
AND MODERATE (3 OUT OF 5)RISK FOR EXCESSIVE RAINFALL REMAIN IN
PLACE WITH THE HEAVIEST RAINS POSSIBLE IN THE 6 TO 12 UTC WINDOW
COINCIDING WITH THE DEVELOPMENT OF A 30 TO 40 KNOTS LOW LEVEL
JET INTO EASTERN IOWA AND NORTHWEST ILLINOIS WHICH WILL HELP TO
ENHANCE LIFT AND MOISTURE AND INSTABILITY ADVECTION TONIGHT.
STRONG MOISTURE ADVECTION WITH THE LOW LEVEL JET TONIGHT IS
FORECAST TO INCREASE PRECIPITABLE WATER VALUES OF 2.00 TO 2.30
INCHES. FURTHER INCREASING CONFIDENCE IN HEAVY RAINFALL RATES.
AT THIS TIME THE HEAVIEST RAINFALL IS FORECAST TO FALL WEST OF
THE MISSISSIPPI RIVER. SHOWERS AND STORMS ARE FORECAST TO COME
TO AN END FROM WEST TO EAST SUNDAY MORNING. AFTER THIS EXITS TO
THE EAST, A QUIET PERIOD IS EXPECTED THROUGH THE AFTERNOON.
SUNDAY NIGHT:
THIS PATTERN LOOKS TO REPEAT ITSELF AGAIN LATER SUNDAY/SUNDAY
NIGHT WITH ADDITIONAL ROUNDS OF CONVECTION FIRING TO OUR WEST
ACROSS CENTRAL IOWA AND THEN TRACKING TOWARD THE EAST INTO OUR
FORECAST AREA. BY THIS TIME, PARTS OF THE AREA WILL LIKELY BE
SATURATED FROM THE SEVERAL INCHES OF RAIN THAT MAY HAVE ALREADY
FALLEN, SO IT WON'T TAKE MUCH TO REACH FLASH FLOOD GUIDANCE WITH
MOST OF WHAT FALLS BEING IMMEDIATELY CONVERTED TO RUNOFF.FOR
THESE REASONS, A DAY 2 MODERATE RISK FOR EXCESSIVE RAINFALL HAS
BEEN ADDED.
LONG TERM /MONDAY NIGHT THROUGH SATURDAY/
ISSUED AT 315 AM CDT SAT AUG 9 2025
ACTIVE WEATHER IS EXPECTED EARLY IN THE WEEK WITH A SURFACE
BOUNDARY DRAPED ACROSS EASTERN IOWA AND NORTHWEST ILLINOIS, AND
SOUTHWESTERLY FLOW ALOFT GUIDING OCCASIONAL COMPLEXES OF
SHOWERS AND THUNDERSTORMS THROUGH THE REGION. THIS COULD RESULT
IN ADDITIONAL AREAS OF HEAVY RAINFALL, MAINLY ON MONDAY AND
MONDAY NIGHT. A SHORTWAVE TROUGH IS FORECAST TO SWING THROUGH
THE GREAT LAKES ON TUESDAY, WHICH SHOULD HELP TO PUSH THE FRONT
TO THE SOUTHEAST OF THE AREA AND GIVE US A REPRIEVE FROM THE
HEAVY RAIN. SEASONABLE TEMPERATURES IN THE 80S AND HUMID
CONDITIONS LOOK TO CONTINUE THROUGH THE WEEK.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1231 AM CDT SUN AUG 10 2025
CONVECTION IS LIKELY TO BLOSSOM ACROSS IOWA OVERNIGHT AND DEVELOP
NORTHEASTWARD WITH TIME. RECENT TRENDS HAVE SLOWED THE ONSET, BUT IT
STILL SEEMS LIKELY TO GET GOING BY 08Z PARTICULARLY CLOSER TO KCID.
A SECOND WAVE OF CONVECTION OVER NEBRASKA LIKELY WILL CONGEAL WITH
THE INITIAL ACTIVITY AND IMPACT THE TERMINALS DURING THE MORNING ON
SUNDAY WITH IFR/MVFR CIGS/VSBYS LIKELY. A LULL IS THEN EXPECTED BY
MIDDAY/EARLY AFTERNOON, BUT ADDITIONAL SCATTERED SHOWERS AND STORMS
ARE POSSIBLE LATER IN THE AFTERNOON AND EVENING.
HYDROLOGY
ISSUED AT 1236 PM CDT SAT AUG 9 2025
SEVERAL ROUNDS OF STORMS ARE FORECAST IN THE NEXT 24-36 HOURS ACROSS
THE FORECAST AREA. WIDESPREAD RAIN TOTALS BETWEEN 1-3 INCHES WILL BE
POSSIBLE, WITH SOME LOCALIZED TOTALS OVER 4-5 INCHES. SOME OF THIS
RAIN COULD ALSO FALL IN A VERY SHORT AMOUNT OF TIME RESULTING IN
FLASH FLOODING OVER VERY WET GROUND OR IN URBAN AREAS.
THERE REMAINS HIGH UNCERTAINTY WHERE EXACTLY THE HIGHER TOTALS
ARE EXPECTED TO FALL. WHERE THIS OCCURS WILL BE KEY HOW HIGH
AND HOW FAST THE RIVERS WILL RESPOND OVER THE COMING WEEK. WITH
THE NEW 24- HR QPF FORECASTS TODAY AND WITH MOST STREAMFLOW
VALUES IN THE IOWA TRIBS RUNNING ABOVE NORMAL, NEW FLOOD WATCHES
HAVE BEEN ISSUED FOR THE FOX RIVER AT WAYLAND AND FOR THE DES
MOINES RIVER AT ST. FRANCISVILLE. ADDITIONAL CHANGES CAN BE
EXPECTED IN SUBSEQUENT FORECASTS AS WATER FALLS INTO THE RIVER
SYSTEM.
DVN WATCHES/WARNINGS/ADVISORIES
IA...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR IAZ040>042-051>054-
063>068-076>078-087>089-098-099.
IL...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR ILZ001-002-007-009-
015-016-024>026-034.
MO...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR MOZ009-010.
UPDATE...GIBBS
SHORT TERM...COUSINS/UTTECH
LONG TERM...UTTECH
AVIATION...NWS
HYDROLOGY...GROSS
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