230
FXUS63 KDVN 181117
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
617 AM CDT TUE AUG 18 2026
..UPDATED FOR 12Z AVIATION
KEY MESSAGES
- A STORM SYSTEM WILL PASS THROUGH THE AREA TODAY INTO WEDNESDAY
MORNING, BRINGING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. A
FEW STORMS MAY BE STRONG TO SEVERE, BUT CONFIDENCE IS LOW.
- ANOTHER STRETCH OF QUIETER WEATHER RETURNS LATE IN THE WEEK
AND INTO THE WEEKEND, WITH LIMITED PRECIPITATION CHANCES.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 133 AM CDT TUE AUG 18 2026
UPPER LEVEL NORTHWEST FLOW WILL GUIDE ANOTHER SHORTWAVE TROF
THROUGH THE AREA TONIGHT, WITH WEAK BOUTS OF ENERGY PASSING
OVERHEAD AHEAD OF IT THROUGH THE DAYTIME. A 20-30 KT LLJ WILL
SUPPLY THE NECESSARY MOISTURE TO FAVOR THE DEVELOPMENT OF
SHOWERS AND EMBEDDED THUNDERSTORMS TODAY. AS WE HAVE SEEN IN THE
RECENT FORECAST PACKAGES, THE SHOWERY ACTIVITY CONTINUES TO
TREND EARLIER ON ONSET FOR OUR AREA. WE ARE NOW LOOKING AT THE
POTENTIAL FOR SHOWERS WITH SOME EMBEDDED THUNDER MOVING INTO OUR
NORTHWEST AS EARLY AS MID MORNING. OVERALL, FORCING OVER THE
AREA WILL BE LACKING, WHICH SHOULD LIMIT OVERALL IMPACTS AS THIS
MOVES THROUGH THE AREA THIS MORNING AND EARLY AFTERNOON. AS THE
MAIN UPPER WAVE AND ASSOCIATED COLD FRONT APPROACH THE AREA
THIS EVENING/TONIGHT, THERE WILL BE THE CHANCE FOR REDEVELOPMENT
OF SHOWERS/STORMS. ALTHOUGH, CONFIDENCE CONTINUES TO DECREASE
ON THIS OCCURRING, AS SHORT TERM GUIDANCE CONTINUES TO TREND
MORE DRY. THIS LATE AFTERNOON AND EVENING DEVELOPMENT WILL BE
CONDITIONAL ON IF WE CAN DESTABILIZE THE ENVIRONMENT ENOUGH IN
THE AFTERNOON. OVERALL FORCING SEEMS TO REMAIN WEAKER THOUGH,
WHICH SHOULD HELP LIMIT CONVECTIVE COVERAGE TO ISOLATED-
SCATTERED ALONG THE COLD FRONT. IF WE MANAGE TO REDEVELOP
STORMS, THE ENVIRONMENT WOULD FAVOR A FEW STRONG TO SEVERE
STORMS, WITH THE SPC HIGHLIGHTING OUR WHOLE AREA IN A MARGINAL
RISK, LEVEL 1/5, FOR SEVERE WEATHER. PRIMARY THREATS WITH ANY
STORM WILL BE DAMAGING WINDS, WITH HAIL SECONDARY.
THE COLD FRONT WILL BE SLOW TO MOVE OUT OF THE AREA TONIGHT,
WITH IT REACHING THE INTERSTATE 80 CORRIDER AROUND SUNSET THIS
EVENING. THIS WOULD LEAVE AREAS NORTH OF THE INTERSTATE MOSTLY
DRY THROUGH TONIGHT, WITH THE CHANCE FOR ISOLATED-SCATTERED
STORMS REMAINING FOR AREAS SOUTH OF INTERSTATE 80 THROUGH THE
NIGHT. BY SUNRISE ON WEDNESDAY, THE COLD FRONT WILL HAVE EXITED
THE AREA, WITH ONLY A FEW POST-FRONTAL SHOWERS REMAINING FOR THE
WEDNESDAY MORNING COMMUTE ALONG/SOUTH OF HIGHWAY 34.
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
ISSUED AT 133 AM CDT TUE AUG 18 2026
WE MAY CONTINUE TO SEE SOME RESIDUAL SHOWERS EARLY WEDNESDAY
MORNING, BUT SHOULD LARGELY EXIT THE AREA BY MID MORNING. POST-
FRONTAL AIRMASS WILL KICK IN WEDNESDAY, WITH LIGHT NORTHEASTERLY
WINDS AND DECREASING CLOUD COVER. HIGH PRESSURE WILL APPROACH THE
AREA LATER ON WEDNESDAY, TRACKING THROUGH THE GREAT LAKES REGION ON
THURSDAY. THIS WILL LEAD TO A LARGELY QUIET SECOND HALF OF THE WEEK,
WITH MOSTLY DRY CONDITIONS AND TEMPERATURES SLIGHTLY COOLER. WEAK
NORTHWESTERLY FLOW WILL REMAIN OVERHEAD, WITH A FEW WEAK
IMPULSES IN THE FLOW. ALTHOUGH, WITH LOW MOISTURE AND LACKING
RETURN FLOW, WE ARE NOT EXPECTING MUCH RAIN FOR THE REST OF THE
WEEK. IF WE MANAGE TO SEE ANY SHOWERS FROM THESE PASSING WAVES,
THEY WILL LARGELY BE IN THE FORM OF ISOLATED INSTABILITY
SHOWERS. GUIDANCE CONTINUES TO FAVOR THE BETTER CHANCES FOR
THESE SHOWERS ON FRIDAY, WITH 20-40% POPS. DUE TO LOW MOISTURE
CONTENT, ACCUMULATIONS WOULD BE LOW WITH THESE SHOWERS, WHERE
MOST LOCATIONS ARE LIKELY TO REMAIN DRY AT THIS TIME. IN THE
END, A MUCH NEEDED STRETCH OF MOSTLY-DRY WEATHER WILL BE SEEN
LATE WEEK AND THROUGH THE WEEKEND, WITH COMFORTABLE HUMIDITY AND
TEMPERATURES LARGELY IN THE UPPER 70S.
AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/
ISSUED AT 605 AM CDT TUE AUG 18 2026
OVERALL, PREDOMINANTLY VFR CONDITIONS EXPECTED DURING THE PERIOD.
THERE IS CHANCES FOR SHRA/TSRA AND AREAS OF MVFR/LOCAL IFR
CONDITIONS (VISIBILITY), BUT CONFIDENCE IS PRETTY LOW WITH
COVERAGE AND TIMING.
ONGOING POCKETS OF CONVECTION FAR NORTHERN IA/SOUTHWEST WI, AND
A LARGER AREA SOUTHWEST IA/EASTERN NE SHOULD ALL WEAKEN WITH
TIME AND EASTWARD EXTENT. HOWEVER, SOME SPOTTY SHRA MAY BE ABLE
TO PERSIST INTO PORTIONS OF EASTERN IOWA THIS MORNING INTO MIDDAY.
ANOTHER OPPORTUNITY FOR SHRA AND A FEW TSRA LOOKS TO BE LATER
THIS AFTERNOON INTO EVENING, PARTICULARLY AT THE NORTHERN SITES
(CID/DBQ). HOWEVER, WEAK FRONTAL CONVERGENCE COUPLED WITH
ELONGATED PRESENTATION OF THE MID/UPPER LEVEL ENERGY OWES TO
CONSIDERABLE UNCERTAINTY WITH COVERAGE AND ESPECIALLY FURTHER
SOUTH TOWARD I-80 ON SOUTHWARD AWAY FROM THE UPPER LIFT INTO
MORE CAPPING. WILL PLAN TO GO NO HIGHER THAN PROB30 MENTION FOR
SHRA AT THIS TIME AND TARGET WEST OF MISSISSIPPI RIVER LATER
THIS MORNING THROUGH MIDDAY, AND THEN MAINLY CID/DBQ MID
AFTERNOON INTO EARLY EVENING. CAN'T RULE OUT ANOTHER POTENTIAL
FOR SHRA/TSRA AFTER 06Z MAINLY SOUTH OF I-80, BUT TOO LOW
CONFIDENCE AND BEING LATE IN THE PERIOD I HAVE LEFT THIS OUT OF
BRL/MLI TAFS FOR NOW. WINDS WILL REMAIN LIGHT AND VARIABLE
THROUGH THE START OF THE TAF PERIOD, BECOMING SOUTHWESTERLY
AROUND 10 KT LATER THIS MORNING/AFTERNOON AND THEN VEER
LIGHT WEST/NORTHWEST TONIGHT WITH THE WEAK FRONTAL ZONE MOVING
IN.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...GUNKEL
LONG TERM...GUNKEL
AVIATION...MCCLURE
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