887
FXUS63 KDVN 210817
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
317 AM CDT WED MAY 21 2025
KEY MESSAGES
- COOLER THAN NORMAL TEMPERATURES TO END THE WEEK AND THROUGH
THE WEEKEND BEFORE SLOWLY WARMING NEXT WEEK.
- RAIN CHANCES OVER THE WEEKEND ARE CONDITIONAL BUT THERE SHOULD
BE MANY HOURS OF DRY WEATHER.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 316 AM CDT WED MAY 21 2025
A WEAK LOW MOVING ALONG THE INVERTED TROF ACROSS THE AREA THAT WILL
ALLOW ISOLATED TO SCATTERED SHOWERS TO PERSIST THROUGH SUNRISE.
AFTER SUNRISE, THE AREAL COVERAGE OF SHOWERS WILL DECREASE AS THE
LIFT ASSOCIATED WITH THE LOW EXISTS THE AREA. HOWEVER, THE
PERSISTENT LOW CLOUDS MAY KEEP AREAS OF DRIZZLE GOING ACROSS MUCH OF
THE AREA.
DURING THE AFTERNOON ANOTHER ROUND OF DIURNAL SHOWERS ARE EXPECTED
TO DEVELOP WITH THE ARRIVAL OF A WEAK UPPER LEVEL DISTURBANCE. AREAS
NORTH OF I-80 LOOK TO BE THE FAVORABLE LOCATION FOR ANY RAIN SHOWERS.
THE RAIN SHOWERS THAT DEVELOP DURING THE AFTERNOON WILL SLOWLY
DISSIPATE AFTER SUNSET. HOWEVER, THE PERSIST WEAK INVERTED SURFACE
TROF ACROSS THE AREA IS EXPECTED TO ALLOW ISOLATED RAIN SHOWERS TO
PERSIST THROUGH THE NIGHT.
LONG TERM /THURSDAY THROUGH TUESDAY/
ISSUED AT 316 AM CDT WED MAY 21 2025
THURSDAY
ASSESSMENT...VERY HIGH (>90%) OF COOLER THAN NORMAL TEMPERATURES.
MEDIUM (40-60%) CONFIDENCE ON ISOLATED SHOWERS.
THE WEAK INVERTED TROF REMAINS ACROSS THE AREA WHILE ANOTHER WEAK
UPPER LEVEL DISTURBANCE MOVES THROUGH THE AREA. THUS, THE MORNING
HOURS SHOULD CONTINUE TO SEE PLENTY OF CLOUDS WITH ISOLATED SHOWERS.
AS THE DISTURBANCE EXITS THE AREA DURING THE AFTERNOON, CLOUDS WILL
SLOWLY BREAK UP AS THE SHOWERS SLOWLY DISSIPATE.
THURSDAY NIGHT THROUGH FRIDAY NIGHT
ASSESSMENT...MEDIUM TO HIGH (60-80%) CONFIDENCE OF DRY BUT COOLER
THAN NORMAL CONDITIONS.
COOL CANADIAN HIGH PRESSURE SLOWLY BUILDS INTO THE MIDWEST WHICH
WILL KEEP TEMPERATURES BELOW NORMAL AND DRY CONDITIONS ACROSS THE
AREA.
SATURDAY THROUGH TUESDAY
ASSESSMENT...LOW (<25%) CONFIDENCE REGARDING PRECIPITATION CHANCES.
THE GLOBAL MODELS (BOTH DETERMINISTIC AND ENSEMBLES) DIFFER ON THE
SENSIBLE WEATHER. THE KEY FACTOR APPEARS TO BE THE POSITION AND
STRENGTH OF THE CANADIAN HIGH PRESSURE.
THE DETERMINISTIC ECMWF/ICON/CMC/UKMET ARE ALL DRY WHILE THE GFS HAS
PRECIPITATION DUE TO THE GFS POSITION OF THE HIGH BEING FURTHER
NORTH AND WEAKER.
INTERESTINGLY, A MAJORITY OF THE ENSEMBLE MEMBERS FROM THE
EPS/GEPS/ICON-EPS/GEFS SUGGEST THE POTENTIAL FOR PRECIPITATION. THE
UKMET GREPS 'SUGGESTS' DRY.
THE FORECAST THUS REFLECTS THE WETTER SOLUTIONS/ENSEMBLES. THERE
DOES APPEAR TO BE SOME AGREEMENT THAT RAIN MAY OCCUR LATE SATURDAY
AFTERNOON INTO SUNDAY MORNING FOR AREAS SOUTH OF I-80 DUE TO THE
PASSAGE OF A STORM SYSTEM.
FOR THE REST OF THE TIME PERIOD THE FORECAST HAS A 20 TO 40 PERCENT
CHANCE OF RAIN.
THE IMPORTANT MESSAGE IS THAT WHILE THERE IS A DAILY RISK OF RAIN,
THERE WILL BE MANY HOURS OF DRY WEATHER.
AVIATION /06Z TAFS THROUGH 06Z THURSDAY/
ISSUED AT 1236 AM CDT WED MAY 21 2025
WIDESPREAD IFR/LIFR CONDITIONS WILL PERSIST THROUGH 18Z/21
ACROSS MUCH OF EASTERN IOWA AND NORTHERN ILLINOIS WITH SCATTERED
SHOWERS OR AREAS OF DRIZZLE. AFTER 18Z/21 CIGS WILL SLOWLY
IMPROVE TO IFR/MVFR WITH ISOLATED DIURNAL SHRA MAINLY NORTH OF
INTERSTATE 80. AFTER 00Z/22 A VERY SLOW IMPROVEMENT TO MVFR/VFR
CIGS WILL BE SEEN.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...08
LONG TERM...08
AVIATION...08
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