322
FXUS63 KDVN 201905
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
205 PM CDT SAT JUN 20 2026
KEY MESSAGES
- WIDESPREAD RAINFALL IS EXPECTED EARLY SUNDAY MORNING THROUGH SUNDAY
EVENING (70-100% RAIN CHANCES). ACCUMULATIONS OF 1-3 INCHES
ARE LIKELY ALONG AND SOUTH OF HIGHWAY 34, WITH A MODERATE RISK
(LEVEL 3 OF 4) FOR EXCESSIVE RAINFALL REMAINING ACROSS
PORTIONS OF NORTHEAST MISSOURI INTO WEST-CENTRAL ILLINOIS.
- A MARGINAL RISK (LEVEL 1 OF 5) FOR SEVERE WEATHER REMAINS FOR SUNDAY,
MAINLY SOUTH OF HIGHWAY 34. PRIMARY THREAT IS DAMAGING WINDS,
WITH A LOWER CHANCE OF A TORNADO.
- WEAK DISTURBANCES AND NORTHWESTERLY FLOW ALOFT TO KEEP TEMPERATURES
COMFORTABLE AND SLIGHTLY BELOW AVERAGE THROUGH THE END OF
NEXT WEEK.
SHORT TERM /THROUGH SUNDAY NIGHT/
ISSUED AT 157 PM CDT SAT JUN 20 2026
MOST OF TONIGHT SHOULD REMAIN QUIET AS THE LAST BITS OF SURFACE HIGH
PRESSURE SHIFT OFF TO THE EAST, GIVING WAY TO A RAINY SYSTEM TO
IMPACT THE AREA ON SUNDAY. LIGHT AND VARIABLE WINDS ARE EXPECTED
UNDER THE HIGH PRESSURE, WITH LOW TEMPERATURES DIPPING TO THE MIDDLE
TO UPPER 50S FOR MOST LOCATIONS.
OKAY, LET'S TALK THE SUNDAY SYSTEM. A MID-LEVEL SHORTWAVE TROUGH,
CURRENTLY SEEN OVER THE ROCKIES PER LATEST GOES-EAST MID-LEVEL WATER
VAPOR IMAGERY, WILL CONTINUE TO TRANSLATE EASTWARD WITH TIME TONIGHT
INTO SUNDAY. AN ATTENDANT AREA OF LOW PRESSURE WILL DEVELOP VIA LEE
CYCLOGENESIS, AND BOTH THE GEFS AND ECMWF ENSEMBLES SUGGEST THE LOW
TRACK WILL BE ALONG THE IOWA/MISSOURI BORDER. A POTENT 35 TO 45 KNOT
LLJ WILL SUPPORT ENHANCED MOISTURE TRANSPORT TOWARDS OUR REGION. THE
SIGNAL AMONG ALL OF THE VARIOUS ENSEMBLE GUIDANCE CONTINUES TO SHOW
THIS SYSTEM PACKING ANOMALOUSLY HIGH MOISTURE, WITH THE 20.12Z HREF
ENSEMBLE PWAT VALUES AROUND 1.5 UP TO 2 INCHES - HIGHEST ACROSS OUR
SOUTHERN TIER OR TWO OF COUNTIES CLOSER TO THE LLJ AND HIGHER
INTEGRATED WATER VAPOR TRANSPORT. THESE VALUES WOULD BE IN EXCESS OF
THE 98TH PERCENTILE PER THE ECMWF PRECIPITABLE WATER CLIMATOLOGICAL
PERCENTILES, SO ANOMALOUSLY HIGH EVEN FOR THIS TIME OF THE YEAR. AS
FAR AS QPF IS CONCERNED, ONE THING THAT WAS NOTICED IS THAT A
DPROG/DT OF THE LATEST HREF ENSEMBLE PROBABILITY-MATCHED MEAN QPF
SHOWS A NORTHERN SHIFT IN THE AXIS OF THE HEAVIEST QPF, LIKELY OWING
TO A MORE POLEWARD SHIFT IN THE NOSE OF THE LLJ. THE 6-HOUR PMM QPF
PER THE HREF BETWEEN 12Z-18Z SUNDAY IS NOW AROUND 2-3+", CENTERED ON
THE HIGHWAY 34 CORRIDOR AND POINTS SOUTH, WHICH HAS LED TO CONTINUED
CONCERN FOR FLASH FLOODING POTENTIAL GIVEN THAT THE LATEST FLASH
FLOOD GUIDANCE VALUES ARE NOW AROUND 2 INCHES IN THESE AREAS. DUE TO
THIS NORTHERN SHIFT, WE DECIDED TO EXPAND THE FLOOD WATCH NORTHWARD
TO THE HIGHWAY 34 CORRIDOR (NOW VALID THROUGH 00Z MONDAY/7 PM
SUNDAY). IF THE NORTHERN TREND IN HIGHER QPF CONTINUES, IT'S
POSSIBLE WE WILL NEED TO EXPAND THE FLOOD WATCH EVEN FURTHER. THE
LATEST EXCESSIVE RAINFALL OUTLOOK FROM WPC INDICATES LITTLE CHANGE,
WITH A MODERATE RISK (LEVEL 3 OF 4) FOR OUR SOUTHERN TIER OF
COUNTIES, AND A SLIGHT RISK (LEVEL 2 OF 4) FOR AREAS SOUTH OF
HIGHWAY 30.
AS FOR THE SEVERE WEATHER POTENTIAL, THERE HASN'T BEEN MUCH CHANGE
IN THAT AS SPC CONTINUES TO MAINTAIN A MARGINAL RISK (LEVEL 1 OF 5)
FOR OUR SOUTHERN TIER OF COUNTIES. WHILE THE MORNING WILL BRING THE
BULK OF THE RAINFALL FOR THIS EVENT, THE AFTERNOON COULD BE OUR
PERIOD TO WATCH FOR ANY ISOLATED STRONG/SEVERE STORMS AS THE ACTUAL
SURFACE LOW TRANSLATES ACROSS OUR SOUTH AT THAT TIME. THERE ARE
QUESTIONS ON HOW MUCH DESTABILIZATION WILL OCCUR DUE TO THE
RESULTING RAIN-COOLED AIR. AT THE MOMENT, DAMAGING WINDS APPEAR TO
BE THE PRIMARY THREAT WITH ANY SEVERE STORMS, GIVEN DEEP-LAYER SHEAR
VALUES AROUND 35 TO 45 KNOTS AND MODEST INSTABILITY, WITH SBCAPE
VALUES AROUND 500-1000 J/KG PER THE HREF ENSEMBLE. ONE THING TO
WATCH FOR IS THE (LOWER) POTENTIAL FOR TORNADOES AS LOW-LEVEL SHEAR
LOOKS ACTUALLY PRETTY DECENT (100 TO 200 M2/S2 OF 0-1 KM SRH).
HOWEVER, STORMS WILL NEED TO BECOME SURFACE-BASED IN ORDER TO TAP
INTO THIS KIND OF AVAILABLE STREAMWISE VORTICITY, SO THIS APPEARS TO
BE A MORE UNLIKELY THREAT. EVEN IF SEVERE WEATHER DOESN'T
MATERIALIZE, A TIGHT SURFACE PRESSURE GRADIENT SHOULD STILL SUPPORT
SOME GUSTY EAST-NORTHEAST WINDS, WITH GUSTS LIKELY AROUND 20 TO 30
MPH.
EVENTUALLY, THE SURFACE LOW PRESSURE SYSTEM WILL EXIT THE REGION TO
THE EAST, BRINGING THE BULK OF THE SHOWERS AND THUNDERSTORMS TO AN
END. THERE COULD BE SOME LINGERING LIGHT SHOWERS IN THE EVENING AS
THE MID-LEVEL SHORTWAVE LAGS BEHIND THE SURFACE LOW, BUT CONFIDENCE
IN THIS IS FAIRLY LOW (20-40% CHANCES). OTHERWISE, SUNDAY NIGHT
LOOKS TO BE LARGELY DRY, WITH LOWS FALLING TO THE LOWER TO MIDDLE
50S.
LONG TERM /MONDAY THROUGH FRIDAY/
ISSUED AT 157 PM CDT SAT JUN 20 2026
MONDAY-TUESDAY...BEHIND THE SUNDAY SHORTWAVE, ZONAL FLOW RETURNS
ALOFT, KEEPING CONDITIONS DRY ON MONDAY. NORTHERLY WINDS AT THE
SURFACE WILL KEEP HIGHS IN THE 70S AND LOWS IN THE 50S MONDAY INTO
TUESDAY MORNING UNDERNEATH PARTLY CLOUDY SKIES. ON TUESDAY, THE NEXT
SHORTWAVE TROUGH DIGS SOUTHWARD INTO THE NORTHERN PLAINS. ANOTHER
LOW PRESSURE DEVELOPS AHEAD OF THIS TROUGH ACROSS THE DAKOTAS, BUT
THE POSITIVE TILT OF THE TROUGH DOES NOT PROVIDE A LOT OF UPPER
LEVEL SUPPORT FOR DEEPENING. THIS LOW PRESSURE WILL SWING
SOUTHEASTWARD WITH THE TROUGH, BRINGING POPS BACK UP TUESDAY NIGHT
ALONG THE COLD FRONT. THE ORIENTATION OF THIS SYSTEM SHOULD LIMIT
THE SEVERE POTENTIAL.
WEDNESDAY-FRIDAY...AS THE LOW PRESSURE FROM TUESDAY NIGHT CLEARS THE
AREA, A WEAK SURFACE TROUGH DEVELOPS ON THE BACKSIDE, KEEPING SOME
LIGHT SHOWERS AROUND AS THE POSITIVELY-TILTED UPPER-LEVEL TROUGH
MOVES OVER IOWA. POPS SHOULD DROP OFF HEADING INTO WEDNESDAY
NIGHT AS CONVERGENCE ALOFT ON THE BACKSIDE OF THE TROUGH ALLOWS
FOR SUBSIDENCE TO SET IN. WEAK PERTURBATIONS IN THE NORTHWESTERLY
FLOW ALOFT WILL KEEP DIURNAL-DRIVEN SCATTERED POPS ON THE TABLE
FRIDAY. IN ADDITION, WEAK NORTHERLY FLOW AT THE SURFACE DURING
THIS TIME PERIOD SHOULD KEEP HIGHS IN THE 70S (70-90% CHANCE),
BELOW AVERAGE FOR THIS TIME OF YEAR.
AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
ISSUED AT 1236 PM CDT SAT JUN 20 2026
VFR CONDITIONS WILL CONTINUE INTO TONIGHT, WITH ONLY SOME FEW TO
SCT DAYTIME CUMULUS CLOUDS AND PERSISTENT NORTHWEST WINDS AROUND
5-15 KNOTS BECOMING LIGHT AND VARIABLE OVERNIGHT. ATTENTION
WILL THEN TURN TO A RAINY SYSTEM THAT WILL BEGIN MOVING IN FROM
THE WEST AROUND DAWN SUNDAY, BRINGING BOUTS OF HEAVY RAINFALL
WITH IT (70-100% CHANCE). AS A RESULT, MVFR TO IFR CEILINGS AND
VISIBILITIES ARE EXPECTED WITH THIS ACTIVITY. THE ONSET TIMING
OF RAIN REMAINS UNCERTAINTY, BUT DECIDED TO FORECAST PREVAILING
SHRA WHEN CONFIDENCE IN RAINFALL WAS HIGH ENOUGH. THERE COULD
ALSO BE SOME EMBEDDED THUNDERSTORMS NEAR BRL, WITH MUCH LOWER
CONFIDENCE IN STORMS FARTHER NORTH.
DVN WATCHES/WARNINGS/ADVISORIES
IA...FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
IAZ087>089-098.
FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
IAZ099.
IL...FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
ILZ025-026.
FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
ILZ034-035.
MO...FLOOD WATCH FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR
MOZ009-010.
SHORT TERM...SCHULTZ
LONG TERM...DELAUNE
AVIATION...SCHULTZ
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