589
FXUS63 KDVN 171640 AAA
AFDDVN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1140 AM CDT WED JUN 17 2026
KEY MESSAGES
- AREAS OF RAIN AND THUNDERSTORMS THIS AFTERNOON, WITH
UNCERTAINTY ON HOW FAR NORTH THE SEVERE THREAT (LEVEL 2/3 OF
5) RETURNS AND ESPECIALLY THE TORNADO THREAT, WITH MAIN
CONCERN ALONG/SOUTH OF U.S. HIGHWAY 34; THREAT ENDS NEAR 6 PM.
- BECAUSE OF THE HEAVY RAIN THIS MORNING IN MANY PLACES AND
NUMEROUS STORMS STILL THIS AFTERNOON (EVEN IF ELEVATED), THERE
WILL BE LOCAL FLASH FLOODING TO CONTINUE OR REDEVELOP,
ESPECIALLY ACROSS METROS.
- QUIET WEATHER WILL BE SEEN THROUGH THE SECOND HALF OF THE
WORK WEEK, WITH THE PATTERN BECOMING ACTIVE AGAIN THIS WEEKEND
AND BEYOND.
UPDATE
ISSUED AT 1135 AM CDT WED JUN 17 2026
OUR FOCUS IS NOW ON THE ASSESSMENT OF MORNING STORMS AND THEIR
EFFECT ON THE AFTERNOON ACTIVITY. WHILE THERE IS A NOTABLE
IMPRINT ON THE TEMPERATURE FIELD, ONE CHALLENGE WITH THIS EVENT
IS THAT IT IS FAR MORE SPRING-LIKE THAN SUMMERTIME. IN OTHER
WORDS, THE STRENGTH OF THE LOW PRESSURE (992 MB) WILL HELP DRIVE
PARAMETER FIELDS BY STRONGER ADVECTION THAN WE WOULD TYPICALLY
SEE IN JUNE. AS A TESTAMENT TO THIS IS AN IMPRESSIVE JUNE
TEMPERATURE GRADIENT ACROSS THE AREA WITH MID TO UPPER 50S NORTH
AND CENTRAL TO LOW 80S JUST SOUTH OF THE CWA.
THE SURFACE WARM FRONT MODULATED BY OUTFLOW FROM THE MORNING
STORMS IS DRAPED JUST SOUTH OF THE CWA BORDER. STRONG WAA ALOFT
AND MOISTURE TRANSPORT ARE RESULTING IN REGULARLY DEVELOPING
THUNDERSTORMS NEAR THE 850 MB FRONTAL ZONE OVER THE I-80
CORRIDOR, WITH MAINLY A FLASH FLOOD THREAT. ALSO IMPRESSIVE
CLOUD-TO-GROUND LIGHTNING EVEN WHEN RAIN RATES DIMINISH SOME.
NEAR THE SURFACE WARM FRONT, SATELLITE INDICATES FAIRLY SOLID
CLOUD COVER NEAR THE IOWA/MISSOURI BORDER. HOWEVER, SOME OF THIS
IS TRANSITIONING TO TOWERING CUMULIFORM CLOUDS FROM NEAR
OTTUMWA SOUTHWESTWARD ALONG A CONFLUENCE AXIS. WE ARE THINKING
THIS MAY BE THE START OF THE AFTERNOON ROUND OF STORMS AS IT
PROGRESSES EASTWARD ACROSS LOCATIONS NEAR/SOUTH OF U.S. HIGHWAY
34, AND LIKELY SOME GRADUAL NORTHEAST EXPANSION, POSSIBLY EVEN
NEAR TO THE I-80 CORRIDOR IN ILLINOIS.
AS UPPER FORCING FROM A 120 KT UPPER JET IMPINGES OVER THIS
AREA, MATURE CONVECTION SHOULD GRADUALLY DEVELOP. THESE STORMS
WILL BE AT LEAST CLOSE TO BEING ROOTED IN THE BOUNDARY LAYER,
BUT EVEN IF SLIGHTLY ELEVATED WILL HAVE SEVERE POTENTIAL. THE
PARAMETER SPACE REMAINS FAVORABLE FOR SIGNIFICANT SEVERE
WEATHER, INCLUDING HAIL EVEN THOUGH WE DID NOT HAVE MUCH WITH
THE MORNING ACTIVITY. OF GREATER CONCERN IS IF ROOTED IN THE
BOUNDARY LAYER THERE WOULD BE THE THREAT OF TORNADOES, SOME
POTENTIALLY SIGNIFICANT GIVEN A STOUT PARAMETER GRADIENT (AS
SHOWN BY A FORECAST STP GRADIENT OF 1-6 BY 3 PM). WHETHER THAT
TRULY MANIFESTS INTO SURFACE-BASED SUPERCELLS IN OUR CWA IS
STILL AN UNCERTAINTY.
NOW THIS IS NOT TO SAY THERE IS NOT A SEVERE, AND EVEN A LOWER
END TORNADO THREAT, FURTHER NORTH TOWARD IOWA CITY AND THE
QUAD CITIES, SIMPLY BECAUSE OF THE DYNAMICS WITH THIS SYSTEM.
DEW POINTS IN THE MID 60S HAVE RETURNED TO CENTRAL IOWA ON
SOUTHEAST WINDS, AND CONTINUED PRESSURE FALLS WILL HELP KEEP
THAT LOW-LEVEL THEAT-A ADVECTION INCREASING AHEAD OF THE LOW
PRESSURE. IN TANDEM WITH EFFECTIVE SHEAR IN THE 1-6 KM LAYER OF
50+ KTS, AT LEAST SOME ORGANIZATION FOR SCATTERED SEVERE IS
PLAUSIBLE, AND WE'LL HAVE TO KEEP A CLOSE EYE ON THE LOW-LEVELS.
AS LONG AS STORMS KEEP REGENERATING ALONG THIS I-80 CORRIDOR,
IT MAY PREVENT TRUE LOW-LEVEL WARMING AND CAPE FROM BUILDING UP
TO THE I-80 CORRIDOR IN OUR CWA.
CONFIDENCE IS HIGH IN ANY SEVERE WEATHER THREAT CLEARING OUR
AREA NEAR 7 PM. ISOLATED SHOWERS AND STORMS IN NORTHWEST
ILLINOIS MAY CONTINUE TO 9 PM BEFORE THE FORCING HAS PUSHED
EAST.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 215 AM CDT WED JUN 17 2026
SEVERE WEATHER IS EXPECTED TODAY AS A SEASONABLY STRONG SYSTEM MOVES
THROUGH THE REGION. THIS WILL BRING TWO ROUNDS OF STORMS TO EASTERN
IOWA, NORTHWEST ILLINOIS, AND NORTHEAST MISSOURI: A FIRST ROUND
IN THE MORNING HOURS (4-9 AM) AND SECOND ROUND IN THE AFTERNOON
HOURS (12-7 PM). MORNING STORMS ARE ANTICIPATED TO HAVE A
PRIMARY THREAT OF LARGE HAIL AND LOW DAMAGING WIND POTENTIAL,
WHILE AFTERNOON STORMS WILL BE CAPABLE OF ALL HAZARDS, INCLUDING
TORNADOES. IN ADDITION, HEAVY RAIN WILL LEAD TO LOCALIZED FLASH
FLOODING, ESPECIALLY IN AREAS THAT SEE REPEATED ROUNDS OF
STORMS.
A STRONG SHORTWAVE WILL MOVE FROM THE NORTHERN PLAINS INTO THE UPPER
MIDWEST THIS MORNING. PRESSURE HEIGHTS ARE NEAR OR AT THE NAEFS
CLIMATOLOGICAL MINIMUM FOR MID-JUNE, WHILE WINDS ALOFT ARE NEAR OR
AT THEIR MAXIMUM. THIS CAN BE SEEN IN A STRONG (50-60 KTS) ZONAL JET
AT 500 MB SAMPLED UPSTREAM WITH TODAY'S 00Z SOUNDINGS. AS THIS
SYSTEM TRANSLATES INTO THE UPPER MIDWEST EARLY THIS MORNING,
SOUTHERLY TO SOUTHWESTERLY FLOW ACROSS THE CENTRAL PLAINS WILL
PROVIDE WARM AIR ADVECTION AND MOISTURE, WHICH WILL AMPLIFY WITH THE
LLJ TOWARDS SUNRISE. AS A RESULT, DEWPOINTS ARE FORECAST TO RISE
INTO THE MID TO UPPER 60S WITHIN A FEW HOURS AFTER SUNRISE, CREATING
A SHARP GRADIENT BETWEEN THE NORTHERN AND SOUTHERN HALVES OF
THE CWA. LIFT ALONG THIS WAA WING WILL PROVIDE THE FOCUS FOR
MORNING CONVECTION, WITH SHOWERS AND STORMS ACROSS THE AREA.
FOR THE MORNING, THE GREATEST RISK FOR SEVERE STORMS IS ALONG AND
SOUTH OF INTERSTATE 80, THOUGH THERE IS SOME UNCERTAINTY GIVEN A
STRONG CAP OVER THE REGION. IF STORMS ARE ABLE TO DEVELOP, SHEAR
MAGNITUDE AND DIRECTION SUGGESTS A MIXED STORM MODE WITH MULTICELL
AND SUPERCELLS STORMS. A FAVORABLE SEVERE ENVIRONMENT OF HIGH LAPSE
RATES (7.5-8.5 DEGC/KM) AND UP TO 2000 J/KG OF MUCAPE WILL SUPPORT A
PRIMARY RISK OF LARGE HAIL. IN ADDITION TO THE RISK OF LARGE HAIL,
HEAVY RAIN WILL BE POSSIBLE WITH THESE THESE STORMS. THIS SHOULD BE
A SOAKING RAIN THIS MORNING AND FLASH FLOODING THREAT SHOULD BE
LIMITED, SAVE FOR AREAS THAT HAVE A LONG RESIDENCE TIME WITH STORMS.
THIS WOULD PRIMARILY OCCUR WITH CELLS THAT MOVE OVER THE SAME AREAS,
AS STORMS IN THIS FIRST ROUND WILL BE MOVING QUICKLY TOWARDS THE
EAST AT 40-50 KTS.
BY MID- TO LATE MORNING, THESE STORMS WILL MOVE EAST INTO CENTRAL
ILLINOIS, GIVING THE AIRMASS TIME TO RECOVER. AT THIS POINT, STRONG
SOUTHWESTERLY FLOW WILL CONTINUE TO FEED IN MOISTURE AND
INSTABILITY, PROVIDING THE ENERGY NECESSARY FOR THE SECOND ROUND OF
STORMS. THE GREATEST AREA OF UNCERTAINTY IS IN HOW MUCH RECOVERY
TIME WILL BE POSSIBLE, AS MORNING STORMS AND SHOWERS COULD PERSIST
LONGER THAN ANTICIPATED. IF THE ATMOSPHERE IS ABLE TO RECOVER
FOLLOWING MORNING STORMS, AN ENVIRONMENT FAVORING SUPERCELLS WILL
DEVELOP, LEADING TO THE POTENTIAL FOR ALL HAZARD SEVERE
THUNDERSTORMS.
AROUND 12 PM, FORCING ALONG THE COLD FRONT WILL PLOW INTO A REGION
OF 2000 (NORTH) TO 4000 (SOUTH) J/KG OF CAPE, PROVIDING THE FORCING
NECESSARY FOR CONVECTIVE INITIATION. THESE STORMS WILL BE FAST
MOVING, WITH A STORM MOTION OF 50 KTS TO THE EAST. LARGE HAIL AND
DAMAGING WINDS ARE POSSIBLE WITH ALL STORMS. TORNADO THREAT WILL BE
MORE LIMITED, WITH THE BEST LOW LEVEL SHEAR SUPPORTING THE HIGHEST
TORNADO THREAT IN WEST-CENTRAL ILLINOIS. THESE STORMS WILL EXIT INTO
CENTRAL ILLINOIS AROUND 6-7 PM.
ONCE THESE STORMS MOVE OFF TO OUR EAST, CAA ADVECTION BEHIND THE
FRONT WILL SUPPORT WESTERLY TO NORTHWESTERLY WINDS UP TO 20-25 MPH,
LEADING TO A BREEZY NIGHT.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 215 AM CDT WED JUN 17 2026
SEVERAL PLEASANT, MAINLY DRY DAYS WILL FOLLOW OUR BIG SYSTEM TODAY.
THIS WILL LEAD TO TEMPERATURES BELOW NORMAL FOR HIGHS AND LOWS
THURSDAY AND FRIDAY. DRY AIR SHOULD KEEP ANY RAIN THREAT LOW,
THOUGH SOME ENERGY SKIRTING BY ALOFT COULD BRING SOME SPRINKLES
OR EVEN A TINY THUNDERSTORM AS EARLY AS FRIDAY NIGHT.
WARM BEGINS TO SPREAD NORTHWARD AGAIN TOWARDS SATURDAY, AS THE FLOW
ALOFT SHIFTS TOWARDS A MORE ACTIVE ZONAL FLOW REGIME. MODELS REMAIN
CONSISTENT IN SHOWING A WARM FRONT DEVELOPING OVER THE MIDWEST
SATURDAY NIGHT, AND HAVING AT LEAST ONE SIGNIFICANT WAVE OF
RAIN AND THUNDERSTORMS/ POTENTIALLY AN MCS SUNDAY AND SUNDAY
NIGHT. THERE IS LATITUDE DIFFERENCES IN THE LATEST
DETERMINISTIC GUIDANCE, WITH THE GFS SHIFTING THAT AXIS A BIT
SOUTH, AND THE EC AND GEM MAINTAINING A MORE NORTHERLY FRONTAL
ZONE. REGARDLESS, THAT WILL BE THE NEXT PERIOD FOR US TO FOCUS
ON FOR BOTH HEAVY RAINFALL AND A THUNDERSTORM RISK.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 648 AM CDT WED JUN 17 2026
A SEVERE, BOWING LINE OF STORMS IS BEARING DOWN ON KCID AROUND
12Z AND WILL QUICKLY TRACK SOUTHEAST THROUGH KMLI AND KBRL IN
THE 13Z TO 14Z TIMEFRAME. THERE HAVE BEEN SEVERAL REPORTS OF
50-60+ KT GUSTS WITH THIS LINE AND EXPECT THAT THREAT, ALONG
WITH HEAVY RAIN, HAIL, LIGHTNING, AND IFR CONDITIONS TO
ACCOMPANY THE LINE OF STORMS. ADDITIONAL STORMS ARE FOLLOWING IN
THE WAKE OF THIS LINE, SO EXPECT SCATTERED TO WIDESPREAD STORMS
THROUGH EARLY AFTERNOON, WITH SOME STRONG TO SEVERE THUNDERSTORM
DEVELOPMENT AGAIN POSSIBLE AT KMLI AND KBRL IN THE EARLY
AFTERNOON WITH POTENTIAL FOR DAMAGING WINDS, HAIL, AND POSSIBLY
TORNADOES. FARTHER NORTH, KDBQ WILL REMAIN NORTH OF THE SEVERE
LINE OF STORMS IN MORE STRATIFORM RAIN WITH EMBEDDED
THUNDERSTORM ACTIVITY AND OCCASIONAL LIGHTNING THROUGH AROUND
18-19Z. ADDITIONAL ISOLATED STORMS ARE POSSIBLE WITH THE COLD
FRONTAL PASSAGE LATE THIS AFTERNOON INTO EARLY EVENING FOR KCID,
KDBQ, AND KMLI, AND A LOWER POTENTIAL (LESS THAN 30%) AT KBRL.
WINDS REMAIN BREEZY THROUGHOUT THE DAY OUTSIDE OF STORMS, WITH
BREEZY WINDS AND VFR CONDITIONS BEHIND STORMS THIS AFTERNOON
AND EVENING. LOW-LEVEL WIND SHEAR DEVELOPS AT MOST TERMINALS
AGAIN FOR A FEW HOURS THIS EVENING.
DVN WATCHES/WARNINGS/ADVISORIES
IA...FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR IAZ063>068-076>078-
087>089-098-099.
IL...FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR ILZ009-015>018-
024>026-034-035.
MO...FLOOD WATCH UNTIL 7 PM CDT THIS EVENING FOR MOZ009-010.
UPDATE...FRIEDLEIN
SHORT TERM...ELLINGWORTH
LONG TERM...ERVIN
AVIATION...NWS
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