008
FXUS63 KDVN 172310
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
610 PM CDT WED SEP 17 2025
KEY MESSAGES
- WARMER THAN NORMAL TEMPERATURES WILL CONTINUE THE REMAINDER OF
THE WEEK AND INTO NEXT WEEK.
- RAIN CHANCES WILL BE ON A SLOW INCREASE THROUGH EARLY NEXT
WEEK. WHILE THERE MAY BE PERIODS OR AREAS THAT HAVE BETTER
RAIN CHANCES, OVERALL AREAL COVERAGE ON AVERAGE WILL LIKELY BE
15-30 PERCENT.
SHORT TERM /THROUGH THURSDAY/
ISSUED AT 246 PM CDT WED SEP 17 2025
WEAK UPPER LEVEL DISTURBANCE INITIATED 20-30 PERCENT COVERAGE OF
SHOWERS AND SOME STORMS ACROSS THE NORTHWEST PARTS OF THE AREA LATE
THIS MORNING THAT HAVE PERSISTED INTO MID-AFTERNOON. THESE SHOWERS
AND FEW STORMS WILL PERSIST INTO THE LATE AFTERNOON AND EVENING.
WITH THE EXCEPTION OF A FEW AREAS, COVERAGE ON ANY RAIN WILL
CONTINUE TO BE ISOLATED TO SCATTERED (15-30 PERCENT).
TONIGHT INTO THURSDAY, THE UPPER LEVEL TROF IN THE PLAINS WILL
SLOWLY MOVE EAST. WATER VAPOR AND MODEL OUTPUT SHOWS THREE OR FOUR
UPPER LEVEL DISTURBANCES WILL ROTATE AROUND THE BASE OF THE TROF AND
MOVE THROUGH EASTERN IOWA THROUGH LATE THURSDAY AFTERNOON. EACH ONE
WILL EITHER INITIATE 15-30 PERCENT COVERAGE OF SHOWERS AND SOME
STORMS (WITH SMALL AREAS OF HIGHER POPS) OR HELP MAINTAIN THEM. EACH
ROUND WILL RUN INTO DRIER AIR ALONG AND EAST OF THE MISSISSIPPI
WHICH WILL CAUSE EACH ROUND TO DISSIPATE UPON REACHING THE RIVER.
SADLY, MOST AREAS WILL REMAIN DRY FOR THE NEXT 36 HOURS. THOSE AREAS
THAT DO SEE RAIN WILL BE THE LUCKY ONES.
LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/
ISSUED AT 246 PM CDT WED SEP 17 2025
THURSDAY NIGHT THROUGH TUESDAY NIGHT
ASSESSMENT...HIGH (>80%) CONFIDENCE ON ABOVE NORMAL TEMPERATURES.
LOW (20-30%) CONFIDENCE ON RAIN CHANCES
THE STRONG UPPER LEVEL RIDGE THAT HAS BEEN OVER THE AREA WILL SLOWLY
SHIFT EAST OF THE AREA AND ALLOW THE UPPER LEVEL TROF IN THE PLAINS
TO MOVE CLOSER TO THE AREA.
THE MODELS SHOW MANY UPPER LEVEL DISTURBANCES WILL ROTATE THROUGH
THE AREA THAT WILL HAVE THE POTENTIAL TO BRING SOME RAIN TO THE
AREA. YESTERDAY THE PROBABILITIES OF SEEING 0.01 INCHES OF RAIN
THROUGH THE WEEKEND WAS NEAR 100 PERCENT FOR THE ENTIRE AREA.
HOWEVER, THE STRETCH OF DRY WEATHER THAT WE HAVE EXPERIENCED HAS
LIKELY RESULTED IN AN INCREASE TO THE NEGATIVE FEEDBACKS WHICH WILL
LOWER THE OVERALL RAIN CHANCES.
AS A RESULT, THE MODEL CONSENSUS IS GENERALLY DEPICTING RAIN CHANCES
AT 20-35 PERCENT EACH PERIOD THROUGH TUESDAY NIGHT WITH TWO
EXCEPTIONS; THURSDAY NIGHT INTO FRIDAY AND SUNDAY NIGHT. THESE TIME
FRAMES THE MODELS DEPICT STRONGER UPPER LEVEL DISTURBANCES WHICH
SUPPORT A BETTER SIGNAL FOR RAIN POTENTIAL; 40-60 PERCENT. HOWEVER,
IF THE NEGATIVE FEEDBACKS ARE ON THE INCREASE, THE CHANCES FOR RAIN
IN THESE TIME FRAMES HAVE THE POTENTIAL TO DECREASE AS WE GET CLOSER
TO THEM.
WEDNESDAY
ASSESSMENT...MEDIUM TO HIGH (60-80%) CONFIDENCE ON DRY CONDITIONS
THE GLOBAL MODELS ARE INDICATING A PATTERN CHANGE TO THE FLOW ALOFT
DEVELOPING AROUND THE MIDDLE OF NEXT WEEK. AS A RESULT, THE MODELS
ARE STRUGGLING ON HOW TO HANDLE UPPER LEVEL ENERGY APPROACHING THE
AREA. THE MODELS TO VARYING DEGREES ARE DEVELOPING A CUT OFF UPPER
LOW BUT DISAGREE ON WHERE THE CUT OFF DEVELOPS OR EVENTUALLY MOVES.
YESTERDAY, THE ECMWF DROPPED THE CUT-OFF LOW TO THE WI/IL BORDER
SUGGESTING COOLER TEMPERATURES AND A RAIN POTENTIAL. TODAY IT HAS NO
CUT-OFF LOW. THE UKMET HAS NO CUT-OFF LOW WHILE THE GFS/CMC TAKE THE
UPPER LOW OVER THE NORTHERN GREAT LAKES INTO SOUTHEAST CANADA. THE
ICON MODEL KEPT THE CUT-OFF LOW WELL NORTH OF THE AREA YESTERDAY AND
TODAY IT BRINGS IT ACROSS THE AREA. SINCE MODEL PREDICTABILITY
NATURALLY LOWERS DURING A PATTERN CHANGE, RUN-TO-RUN TRENDS OF THE
MODELS WILL BE IMPORTANT AS TO WHICH SCENARIO EVENTUALLY PLAYS OUT.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 606 PM CDT WED SEP 17 2025
RAIN SHOWERS AND THUNDERSTORMS CONTINUE OVER CENTRAL IOWA, BUT
CONTINUE TO FALL APART AS THEY SLOWLY MOVE TOWARDS EASTERN IOWA
THIS EVENING. AN OUTFLOW BOUNDARY HAS TEMPORARILY MOVED TO NEAR
CID, RESULTING IN NORTHWEST WINDS GUSTING TO 20 KTS, BUT THIS
WILL ONCE AGAIN REVERT TO LIGHT AND VARIABLE WINDS OVERNIGHT, AT
ALL SITES, AND ALSO THROUGH MOST OF THURSDAY. THOUGH AN
ISOLATED SHOWER OR STORM COULD SPREAD INTO AREAS WEST OF DBQ TO
CID, THOSE CHANCES APPEAR VERY LOW AND UNLIKELY TO IMPACT ANY
TAF SITES THROUGH THURSDAY AFTERNOON. TRENDS WILL BE MONITORED
FROM THE CENTRAL IOWA ACTIVITY, BUT WITH DRY AIR OVER EASTERN
IOWA, WE CONTINUE TO OFFER A VFR CONDITION FORECAST.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...08
LONG TERM...08/12
AVIATION...ERVIN
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