034
FXUS63 KDVN 180527
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1227 AM CDT FRI SEP 18 2026
KEY MESSAGES
- THE WET WEATHER PATTERN WILL CONTINUE THROUGH THE WEEKEND WITH
ROUNDS OF RAIN WHICH MAY BE HEAVY AT TIMES. THERE WILL BE
PERIODS OF DRY WEATHER BETWEEN EACH ROUND.
- THE REPEATED ROUNDS OF RAIN WILL RESULT IN GENERAL RISES ON
THE MISSISSIPPI RIVER WITH THE POTENTIAL FOR RIVER FLOODING ON
TRIBUTARY RIVERS.
SHORT TERM /THROUGH SATURDAY/
ISSUED AT 200 PM CDT THU SEP 17 2026
AS OF EARLY THIS AFTERNOON, A QUASI-STATIONARY FRONT WAS DRAPED
ACROSS EASTERN IOWA INTO NORTHWEST ILLINOIS, APPROXIMATELY
ALONG THE I-80 TO HIGHWAY 30 CORRIDOR. GOES VISIBLE IMAGERY
SHOWED WIDESPREAD LOW CLOUDS NORTH OF THE FRONT WHERE
TEMPERATURES WERE IN THE UPPER 60S TO MID 70S. MAINLY CLEAR
SKIES WERE NOTED SOUTH OF THE BOUNDARY AND TEMPERATURES WERE
MUCH WARMER INTO THE 80S (~UPPER 80S SOUTH OF HIGHWAY 34),
ACCOMPANIED BY VERY HUMID CONDITIONS WITH DEWPOINTS IN THE LOWER
TO MID 70S. THIS HOT AND HUMID AIR MASS HAS PUSHED HEAT INDICES
INTO THE MID 90S TO NEAR 100 DEGREES ACROSS THE FAR SOUTH.
HEADING INTO TONIGHT, WINDS WILL SHIFT TO THE EAST-NORTHEAST IN
RESPONSE TO SURFACE CYCLOGENESIS ALONG THE FRONT RANGE IN
COLORADO. A WAVE OF WARM AIR ADVECTION ALOFT MAY LEAD TO
SCATTERED SHOWERS AND ISOLATED STORMS (20-60%) LATE TONIGHT INTO
FRIDAY MORNING, WORKING WEST TO EAST THROUGH PORTIONS OF THE
AREA. HIGHEST CHANCES FOR SOME MEASURABLE RAIN ARE TO THE WEST
AND NORTHWEST OF THE QUAD CITIES. THIS ACTIVITY LOOKS TO MOVE
THROUGH RELATIVELY QUICKLY, THEREBY LIMITING TOTAL RAINFALL
AMOUNTS WITH MUCH OF THE AREA RECEIVING UNDER 0.25". A FEW
ISOLATED SHOWERS AND STORMS REMAIN POSSIBLE THROUGH FRIDAY
AFTERNOON, BUT WITH MOST OF THE AREA LIKELY TO STAY DRY DURING
THIS PERIOD.
LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
ISSUED AT 200 PM CDT THU SEP 17 2026
THE LOBE OF MID-LEVEL VORTICITY THAT SPAWNED THE COLORADO LOW
MOVES INTO THE UPPER MISSISSIPPI RIVER VALLEY BEFORE BEING
EJECTED EASTWARD BY THE ZONAL FLOW. THIS DRAGS THE LOW PRESSURE
CENTER NORTHEASTWARD TOWARDS IOWA. AS THE WINDS SHIFT TO OUT OF
THE SOUTHEAST, A WARM, MOIST AIR IS PULLED NORTHWARD INTO THE
CWA, SETTING THE STAGE FOR ANOTHER ROUND OF HEAVY RAIN NORTH OF
I-80 FRIDAY NIGHT INTO SATURDAY MORNING. LATEST ENSEMBLE
GUIDANCE SHOWS A SWATH OF 0.25-0.75 OF AN INCH ALONG THE HIGHWAY
20 CORRIDOR (50-70% CHANCE). THE COVERAGE AND INTENSITY OF
THESE STORMS WILL DECREASE THROUGHOUT THE DAY ON SATURDAY BUT
REMAIN SCATTERED NORTH OF I-80 AS THE LOW PRESSURE CENTER
DRIFTS INTO NORTHERN IOWA.
SATURDAY NIGHT-MONDAY...A SHORTWAVE TROUGH THAT HAS BEEN
CAMPING ACROSS THE WESTERN CONUS FOR MOST OF THE WEEK WILL
FINALLY PROPAGATE EASTWARD INTO THE NORTHERN ROCKIES SATURDAY
NIGHT. SHORTWAVE RIDGING OVER THE MID-TO-UPPER MISSISSIPPI RIVER
VALLEY INTRODUCES SOUTHWESTERLY FLOW ALOFT, PULLING ANOTHER
MID-LEVEL VORTICITY LOBE NORTHWARD INTO THE NORTH-CENTRAL
PLAINS. THIS MID-LEVEL TROUGH IS FORECASTED TO REDEVELOP STORMS
(50-70% COVERAGE) ALONG A COLD FRONT MOVING THROUGH THE AREA.
THE SPC HAS A MARGINAL RISK, LEVEL 1 OUT OF 5, FOR MOST OF THE
OUTLOOK AREA FOR ISOLATED DAMAGING WINDS, BUT THE LATEST LREF
GUIDANCE ONLY HAS A 20-40% JOINT PROBABILITY OF SBCAPE EXCEEDING
500 J/KG AND THE SFC-TO-500 MB BULK SHEAR EXCEEDING 30 KNOTS.
THEREFORE, ANY CONVECTION THAT FORMS SHOULD STRUGGLE TO
ORGANIZE.
AFTER SATURDAY NIGHT, SCATTERED POPS (40-70%) WILL STICK AROUND
INTO MONDAY AS WEAK SHORTWAVES ROTATING AROUND THE MAIN TROUGH
AXIS, NOW OVER THE NORTHERN PLAINS, KEEPS CVA OVER THE AREA. BY
MONDAY THOUGH, MOST PRECIPITATION WILL BE IN THE FORM OF RAIN
SHOWERS AS THE BOUNDARY AND LOW PRESSURE OVER MISSOURI DRIFTS
FURTHER SOUTH AND NORTHEASTERLY FLOW FROM A HIGH PRESSURE OVER
ONTARIO PUMPS IN COOLER AIR.
TUESDAY-WEDNESDAY...THE SHORTWAVE TROUGH OVER THE NORTHERN
PLAINS FINALLY REACHES THE MIDWEST ON TUESDAY. ISOLATED COLD-
CORE SHOWERS COULD STICK AROUND DURING THE DAY BEFORE SUBSIDENCE
SETS IN ON THE BACKSIDE OF THE TROUGH HEADING INTO TUESDAY
NIGHT AND WEDNESDAY. THE PERSISTENT NORTHEASTERLY FLOW SHOULD
ALLOW FOR SEASONABLY COOL TEMPERATURES WITH HIGHS ONLY IN THE
LOWER TO UPPER 60S!
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 1227 AM CDT FRI SEP 18 2026
AREAS NORTH OF HIGHWAY 34 ARE CURRENTLY UNDERNEATH A MVFR-TO-
IFR CLOUD DECK WITH CEILINGS BETWEEN 600 AND 1200 FEET. THIS
DECK WILL IMPACT CID, DBQ, AND MLI THROUGH AT LEAST 14 UTC
BEFORE LIFTING THROUGHOUT THE DAY AND SCATTERING OUT FROM
SOUTHEAST TO NORTHWEST. BRL COULD BRIEFLY BE IMPACTED BY THIS
DECK CLOSER TO SUNRISE. LATER IN THE MORNING AND INTO THE EARLY
AFTERNOON, AN ADVANCING WARM FRONT WILL SHIFT THE WINDS OUT OF
THE SOUTHEAST AND BRING ISOLATED TO SCATTERED (30-50% COVERAGE)
SHOWERS TO AREAS ALONG AND NORTH OF I-80. BRIEF PERIODS OF MVFR
VISIBILITIES ARE POSSIBLE WITH THE HEAVIER SHOWERS. THE LOW
COVERAGE AND UNCERTAINTY ON TIMING LED TO ONLY PROB30S BEING
INCLUDED AT CID, DBQ, AND MLI FOR THIS TAF ISSUANCE.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...UTTECH
LONG TERM...DELAUNE
AVIATION...DELAUNE
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