853
FXUS63 KDVN 310805
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 AM CDT FRI JUL 31 2026
KEY MESSAGES
- WIDESPREAD SOAKING RAINFALL IS EXPECTED TODAY THROUGH SATURDAY
WITH AN 80-100% CHANCE OF RAINFALL AMOUNTS OVER 1 INCH AND A
40-70% CHANCE OF RAINFALL AMOUNTS OVER 2 INCHES. A SLIGHT RISK
(LEVEL 2 OF 4) FOR LOCALIZED FLASH FLOODING IS IN EFFECT
AREA-WIDE.
- A CONDITIONAL RISK (LEVEL 1 OF 5) FOR SEVERE THUNDERSTORMS IS
IN EFFECT THIS AFTERNOON INTO THE EVENING FOR AREAS SOUTH OF
HIGHWAY 20. THE PRIMARY THREAT WITH ANY STORMS WILL BE
ISOLATED DAMAGING WINDS. ISOLATED TORNADOES ARE POSSIBLE IN
SOUTHEAST IOWA AND NORTHEAST MISSOURI.
SHORT TERM /THROUGH SATURDAY NIGHT/
ISSUED AT 259 AM CDT FRI JUL 31 2026
A DAY OF ON-AND-OFF RAIN IS IN STORE FOR THE AREA TODAY AS A
SEASONABLY STRONG SHORTWAVE TROUGH INTENSIFIES AND MOVES THROUGH THE
AREA. EARLY THIS MORNING, CYCLOGENESIS HAS SUPPORTED THE DEVELOPMENT
OF A SURFACE LOW ALONG THE NE-SD-IA BORDER. IN THE WARM SECTOR,
ADVECTION ALONG THE WARM CONVEYOR BELT HAS SUPPORTED MOISTURE
TRANSPORT INTO MISSOURI AND IOWA WITH PWATS OF 2.0+ INCHES. WHILE
THIS IS RATHER ANOMALOUS AT WELL ABOVE 1.7 INCHES, THE 90TH
PERCENTILE, IT IS NOT OUT OF THE QUESTION GIVEN UPSTREAM PWATS OF
2.39 INCHES SAMPLED IN KOAX'S 31/00Z SOUNDING. WITH THIS INCREASING
MOISTURE AND SYNOPTIC UPLIFT ALONG THE EASTERN SIDE OF THIS
INTENSIFYING CYCLONE, A WIDESPREAD RAIN EVENT IS EXPECTED TODAY
THROUGH SATURDAY.
WHILE RAIN IS EXPECTED THROUGHOUT MUCH OF THE DAY, DRY PERIODS ARE
EXPECTED BETWEEN MULTIPLE ROUNDS OF SHOWERS AND STORMS. WHILE SOME
SHOWERS ARE MOVING THROUGH THE AREA NOW, THE MAIN LINE, WHICH IS
CURRENTLY A WEAKENING MCS STRETCHING FROM NORTHEAST KANSAS INTO
CENTRAL IOWA, WILL REACH EASTERN IOWA AROUND DAYBREAK. SHOWERS ARE
EXPECTED AREA-WIDE AS IT MOVES EASTWARD, AND PARTS OF SOUTHEAST IOWA
AND NORTHEAST MISSOURI MAY SEE EMBEDDED THUNDERSTORMS DUE TO MLCAPE
UP TO 500 J/KG. BY EARLY AFTERNOON, THIS LINE OF SHOWERS AND STORMS
WILL PUSH THROUGH WESTERN ILLINOIS, ALLOWING FOR DRY PERIODS AND
POTENTIALLY SOME CLEARING ACROSS EASTERN IOWA AND NORTHEAST
MISSOURI.
ADDITIONAL SHOWERS AND STORMS, INCLUDING SOME STRONG TO SEVERE, ARE
POSSIBLE THIS AFTERNOON THROUGH THE EVENING. ANY CLEARING THAT
OCCURS, COUPLED WITH CONTINUED WAA IN THE WARM SECTOR, WILL LEAD TO
INCREASED INSTABILITY THROUGH THE LOW LEVELS, WITH MUCH OF THE
GUIDANCE SHOWING MLCAPE OF 1000-1500 J/KG. DEEP LAYER SHEAR IS MORE
SUPPORTIVE OF A SEVERE RISK, WITH 25-35 KTS THROUGH MUCH OF THE
AREA. THE PRIMARY THREATS WITH ANY STRONG TO SEVERE STORMS WILL BE
ISOLATED DAMAGING WINDS DUE TO STRONG WINDS ALOFT. A SECONDARY
THREAT IN THE VICINITY OF THE LOW ACROSS SOUTHEAST IOWA AND
NORTHEAST MISSOURI IS AN ISOLATED TORNADO OR LANDSPOUT, AS STRONGER
LOW-LEVEL SHEAR (0-3 KM SRH OF 200-300) AND VEERING PROFILES IN THE
VICINITY OF THE LOW AND COLD FRONT WILL BE SUPPORTIVE OF LOW-TOPPED
SUPERCELLS. GIVEN THESE THREATS, SPC HAS ISSUED A CONDITIONAL
MARGINAL (LEVEL 1 OF 5) RISK FOR AREAS SOUTH OF HIGHWAY 20 AND A
SLIGHT (LEVEL 2 OF 5) FOR THE FAR SOUTHERN REACHES OF THE AREA INTO
EASTERN MISSOURI AND WESTERN ILLINOIS.
SCATTERED SHOWERS WILL CONTINUE OVERNIGHT THROUGH SATURDAY AFTERNOON
AS THE LOW SLOWLY WORKS ITS WAY SOUTHEASTWARD. TOTAL RAINFALL
ACCUMULATIONS THROUGH SATURDAY OF 1-3 INCHES ARE EXPECTED, WITH THE
NBM HAVING AN 80-100% CHANCE OF EXCEEDING 1 INCH AREA-WIDE. SOME
AREAS, PARTICULARLY THOSE IN SOUTHEAST IOWA AND NORTHEAST MISSOURI,
HAVE LOWER CHANCES OF EXCEEDING 2 INCHES, LEADING TO A 40-70%
SOUTHWEST-TO-NORTHEAST GRADIENT OF 2 INCH EXCEEDANCE PROBABILITIES.
SOME GUIDANCE SUGGESTS THAT LOCALLY HIGHER AMOUNTS OF 3-5 INCHES MAY
ALSO BE POSSIBLE. THIS WILL BE QUITE WELCOME DUE TO RECENT DRYNESS,
WHICH IN TURN WILL HELP REDUCE FLOODING RISKS. THE GREATEST CHANCE
FOR ANY FLOODING WILL BE IF SLOW-MOVING HEAVY RAINFALL REPEATEDLY
MOVES OVER URBAN AREAS OR AREAS WITH POOR DRAINAGE. DUE TO THIS, WPC
HAS ISSUED A SLIGHT (LEVEL 2 OF 4) RISK FOR FLASH FLOODING AREA-WIDE
TODAY.
AS SHOWERS END ON SATURDAY AFTERNOON, A STRONG PRESSURE GRADIENT ON
THE BACKSIDE OF THE LOW WILL INDUCE GUSTY NORTHERLY WINDS UP TO 30
MPH THAT LAST THROUGH LATE EVENING.
LONG TERM /SUNDAY THROUGH THURSDAY/
ISSUED AT 259 AM CDT FRI JUL 31 2026
THE UPPER-LEVEL TROUGH THAT WILL HELP BRING PRECIPITATION ACROSS THE
AREA TODAY AND SATURDAY WILL FINALLY DEPART THE REGION TO THE EAST
SUNDAY, LEADING TO A PERIOD OF DRY CONDITIONS. SURFACE HIGH PRESSURE
BUILDING ACROSS THE AREA, ALONG WITH UPPER-LEVEL RIDGING OVER THE
INTERMOUNTAIN WEST REGION PROTRUDING FROM A LARGE UPPER-LEVEL HIGH
OVER THE SOUTHWESTERN CONUS, WILL SUPPORT MORE QUIESCENT CONDITIONS
THROUGH TUESDAY, WITH SEASONAL TEMPERATURES (HIGHS IN THE LOWER 80S)
FOR SUNDAY THROUGH TUESDAY.
IN TERMS OF ACTIVE WEATHER, IT APPEARS MAINLY WEDNESDAY/THURSDAY
WILL BE THE TIME TO WATCH AS THE UPPER-LEVEL RIDGING BREAKS DOWN,
ALLOWING A MID-LEVEL TROUGH TO APPROACH THE REGION. AN ATTENDANT
SURFACE COLD FRONT IS ALSO PROGGED TO ACCOMPANY THE TROUGH, ALTHOUGH
THERE ARE SIGNIFICANT TIMING DIFFERENCES AMONG THE GLOBAL MODELS OF
THE FRONT, AND THUS, TIMING OF PRECIPITATION WITH THAT BOUNDARY.
SEVERE WEATHER POTENTIAL WITH THIS FRONT APPEARS TO BE PRETTY LOW AT
THIS TIME, GIVEN MODEST VALUES OF INSTABILITY AND SHEAR (25-35 KNOTS
FOR 0-6 KM SHEAR MAGNITUDES). THE VARIOUS MACHINE LEARNING SEVERE
WEATHER PROBABILITY GUIDANCE SUPPORTS THE MORE LIMITED SEVERE
WEATHER SIGNAL.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1258 AM CDT FRI JUL 31 2026
GRADUALLY DECREASING FLIGHT CONDITIONS FROM VFR TO PREVAILING MVFR
ARE EXPECTED THROUGH THE TAF PERIOD AS A STORM SYSTEM MOVES THROUGH
THE AREA WITH SCATTERED SHOWERS AND STORMS. CIGS WILL LOWER OVER THE
NEXT SEVERAL HOURS FROM WEST TO EAST, REACHING MVFR AS EARLY AS
31/07Z AT CID TO 31/16Z AT DBQ. IFR CIGS ARE LIKELY (60-80%) AFTER
31/18Z AND WILL CONTINUE PAST THE END OF THE TAF PERIOD. AN INITIAL
CLUSTER OF SHOWERS WILL MOVE THROUGH CID IN THE 31/07-10Z WINDOW
WITH OBSERVED DROPS TO 2SM OR LOWER IN CENTRAL IOWA. BY 31/12Z, THE
MAIN LINE OF SHOWERS AND STORMS WILL REACH WESTERN TERMINALS AND
MAKE ITS WAY EASTWARD THROUGH 31/17Z, AFTER WHICH SCATTERED SHOWERS
(MLI/DBQ) AND THUNDERSTORMS (CID/BRL) WILL BE POSSIBLE WITH IFR
CIGS. WINDS WILL BE SOUTHEASTERLY 8-12 KTS WITH GUSTS TO 25 KTS
POSSIBLE FOR MLI/BRL AS THE STORM SYSTEM STRENGTHENS.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...ELLINGWORTH
LONG TERM...SCHULTZ
AVIATION...ELLINGWORTH
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