616
FXUS63 KDVN 132311
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
611 PM CDT SUN SEP 13 2026
KEY MESSAGES
- ACTIVE PATTERN THIS WEEK TO BRING NUMEROUS ROUNDS OF SHOWERS
AND STORMS WITH HEAVY RAIN POSSIBLE.
- THERE IS A MARGINAL RISK, LEVEL 1 OUT OF 5, FOR SEVERE STORMS
ACROSS THE WESTERN OUTLOOK AREA MONDAY EVENING INTO THE
OVERNIGHT HOURS. PRIMARY HAZARDS WILL BE HEAVY RAIN AND
DAMAGING WINDS.
- AN ELEVATED FLASH FLOOD RISK MAY DEVELOP MID-WEEK WITH
REPEATING ROUNDS OF STORMS. RAINFALL TOTALS OVER 2 INCHES ARE
LIKELY FOR PARTS OF THE AREA, WITH LOCALIZED AREAS OF 4+
INCHES POSSIBLE, LEADING TO RISES ON AREA CREEKS AND STREAMS.
SHORT TERM /THROUGH MONDAY/
ISSUED AT 230 PM CDT SUN SEP 13 2026
ELEVATED POST-FRONTAL SHOWERS AND MID/HIGH CLOUDS HAVE HELD DOWN
TEMPERATURES THIS AFTERNOON, CURRENTLY RANGING FROM THE UPPER
50S ACROSS THE FAR NORTH/NORTHWEST TO MID 70S FAR SOUTHEAST.
SHOWER COVERAGE LOOKS TO INCREASE ALONG AND SOUTH OF THE HIGHWAY
34 COUNTIES THROUGH LATE AFTERNOON AND INTO THE EARLY EVENING
ASSOCIATED WITH A BAND OF ~850MB FGEN. MARGINAL INSTABILITY WITH
MUCAPE OF SEVERAL HUNDRED J/KG COULD SUPPORT A FEW ISOLATED
STORMS IN THIS AREA AS WELL. ONCE THIS UPPER WAVE SHIFTS TO THE
EAST EARLY TONIGHT, HIGH PRESSURE WILL BUILD INTO THE REGION
AND SKIES WILL GRADUALLY CLEAR OUT. A RELATIVELY DRY AIR MASS IN
PLACE AND LIGHT WINDS WILL ALLOW TEMPERATURES TO FALL INTO THE
MID TO UPPER 40S NORTH/NORTHEAST OF THE QUAD CITIES TO MID TO
UPPER 50S ACROSS THE SOUTH.
THE SURFACE HIGH WILL SHIFT TO THE EAST INTO THE GREAT LAKES
REGION ON MONDAY AS LOW PRESSURE ORGANIZES IN THE NORTHERN
PLAINS. THIS WILL RESULT IN INCREASING SOUTHEASTERLY FLOW ACROSS
EASTERN IOWA AND NORTHWEST ILLINOIS WITH WARMER TEMPERATURES
ANTICIPATED (NEAR 80 F FAR SOUTH TO LOW/MID 70S FOR MUCH OF THE
REMAINDER OF THE OUTLOOK AREA). AN ELEVATED WING OF WARM AIR
ADVECTION PASSING THROUGH LATER MONDAY MORNING INTO THE
AFTERNOON, WILL LIKELY LEAD TO SCATTERED SHOWERS AND ISOLATED
STORMS ACROSS THE AREA. THE HIGHEST CHANCES ARE NW OF THE QUAD
CITIES (40-60%) WITH 10-30% ELSEWHERE.
LONG TERM /MONDAY NIGHT THROUGH SUNDAY/
ISSUED AT 230 PM CDT SUN SEP 13 2026
OVERNIGHT MONDAY, A CLOSED HEIGHTS CENTER POSITIONED OVER THE
NORTHERN ROCKIES NEGATIVELY TILTS AS IT LIFTS INTO SOUTH-CENTRAL
CANADA. WIDESPREAD SHOWERS AND STORMS (80-100% COVERAGE) ARE
EXPECTED ALONG THE COLD FRONT MOVING IN FROM THE NORTHWEST, BUT
LACKLUSTER MID-LEVEL LAPSE RATES WILL PUT A HAMPER ON THE
OVERALL INSTABILITY (750-1500 J/KG OF SBCAPE). THIS IS
FORECASTED TO, ONCE AGAIN, LIMIT THE OVERALL SEVERE POTENTIAL.
HOWEVER, THERE IS A BRIEF WINDOW WHERE A MID-LEVEL JET BOOSTS
THE 0-6-KM SHEAR ALONG THE FRONT TO 45+ KNOTS NORTH OF I-80. THE
SPC HAS MAINTAINED A MARGINAL RISK, LEVEL 1 OUT OF 5, FOR
SEVERE STORMS ACROSS THE FAR WESTERN COUNTIES, WITH THE PRIMARY
HAZARD BEING DAMAGING WINDS. BY TUESDAY, STORM COVERAGE AND
INSTABILITY DECREASES AS UPPER- LEVEL DYNAMICAL SUPPORT WEAKENS.
THE COLD FRONT IS FORECAST TO STALL OUT OVER NORTHERN MISSOURI,
SIMILAR TO TODAY'S SET UP, KEEPING STORM CHANCES AROUND THROUGH
THE END OF THE WEEK.
THE SECOND HALF OF THE WEEK IS GOING TO REMAIN STORMY. A RIDGE
OVER THE SOUTHEAST AND A SLOW-MOVING SHORTWAVE TROUGH OVER THE
WESTERN CONUS IS FORECAST TO PULL MULTIPLE, WEAK SUBTROPICAL
TROUGHS NORTHEASTWARD INTO THE MIDWEST. WITH THE STATIONARY
FRONT FROM TUESDAY'S SYSTEM ACTING AS THE SOURCE OF LIFT,
SCATTERED SHOWERS AND STORMS WILL LIKELY DEVELOP DAILY. WITH
SATURATED GROUNDS EXPECTED AFTER THE ROUNDS OF RAIN TODAY
THROUGH TUESDAY, THE FLOOD THREAT WILL BECOME MORE ELEVATED WITH
EACH SUBSEQUENT ROUND, AND WPC HAS HIGHLIGHTED THE AREA WITH A
SLIGHT RISK (LEVEL 2 OF 4) FOR EXCESSIVE RAINFALL THROUGH MUCH
OF THE WEEK.
IN TERMS OF RAINFALL TOTALS, LATEST LREF PROBABILITY FOR 2"+ ARE
60-80% NORTHWEST OF THE QUAD CITIES AND 20-40% TO THE SOUTHEAST.
THERE IS UNCERTAINTY THOUGH IN THE AXIS (OR AXES) OF HEAVIEST
RAINFALL WITH THE LREF 10TH-90TH PERCENTILE SPREAD SHOWING A 2-3
INCH DIFFERENCE AREAWIDE. THEREFORE, WHILE THE PROBABILITIES
ARE LOW (10-20% ACROSS THE NW OUTLOOK AREA, MUCH LOWER
ELSEWHERE) FOR 5+ INCHES OF RAINFALL, THE ENSEMBLE SPREAD IS
SUGGESTING THAT LATEST MODEL GUIDANCE MAY BE UNDERCUTTING THE
HIGH-END TOTALS.
AVIATION /00Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 607 PM CDT SUN SEP 13 2026
RAIN SHOWERS ARE NOW SOUTHEAST OF THE AREA, AND MOVING AWAY FROM
ALL SITES AT THE START OF THE PERIOD. A COOL, QUIET, VFR NIGHT
IS IN STORE FOR THE AREA, POSSIBLY WITH SOME RIVER VALLEY FOG
OVER FAR NORTHWEST ILLINOIS, BUT INCREASING MID CLOUDS LATER
TONIGHT SHOULD KEEP THAT FROM BEING A WIDESPREAD PROBLEM. BY
MORNING, A WARM FRONT ALOFT WILL BEGIN TO SWEEP NORTHEAST OVER
THE REGION, BRINGING A BAND OF RAIN SHOWERS AND POSSIBLE THUNDER
FROM SOUTWEST TO NORTHEAST OVER THE REGION. THESE SHOWERS ARE
EXPECTED TO FAVOR A NORTHERLY TRACK OVER NORTHEAST IOWA, AND I
HAVE INCLUDED A PROB30 FOR 4SM RAIN SHOWERS AT CID AND DBQ
MONDAY DURING THE MID MORNING AND AFTERNOON HOURS, (16-20Z).
WINDS WILL BE LIGHT TONIGHT, AND TURN TO THE EAST/SOUTHEAST
MONDAY MORNING, INCREASING TO 10 TO 23KTS BY MID MORNING,(15-17Z).
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...UTTECH
LONG TERM...DELAUNE/UTTECH
AVIATION...ERVIN
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