907
FXUS63 KDVN 210001
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
701 PM CDT TUE MAY 20 2025
KEY MESSAGES
- A CONDITIONAL SEVERE THREAT (LEVEL 1/2 OUT OF 5) REMAINS IN
PLACE THIS AFTERNOON ALONG/SOUTH OF INTERSTATE 80 AND EAST OF
HIGHWAY 218. THE PRIMARY RISKS LOOK TO BE DAMAGING WINDS AND
TORNADOES.
- GENERALLY COOLER CONDITIONS ARE EXPECTED THROUGH THE UPCOMING
WEEKEND, WITH HIGHS WARMING BACK TO THE UPPER 60S BY FRIDAY
THROUGH THE UPCOMING WEEKEND.
- CHANCES OF LIGHT RAIN WILL REMAIN FOR WEDNESDAY NIGHT, AND
AGAIN SATURDAY THROUGH MONDAY, WITH SOME DRY PERIODS IN
BETWEEN.
SHORT TERM /THROUGH WEDNESDAY/
ISSUED AT 250 PM CDT TUE MAY 20 2025
AFTER SOME SOAKING RAINFALL, WITH SEVERAL LOCATIONS RECEIVING
BETWEEN 1-2" (ISOLATED 3+" WERE SEEN AROUND MACOMB, IL), WE ARE
SEEING AN ONGOING ROUND OF NUMEROUS SHOWERS AND THUNDERSTORMS
THIS AFTERNOON, WHICH WILL CONTINUE INTO THE EARLY EVENING.
ALOFT, A LONGWAVE UPPER-LEVEL TROUGH OVER THE CENTRAL PLAINS
REGION WILL CONTINUE TO APPROACH OUR REGION, BECOMING MORE
NEGATIVELY-TILTED WITH TIME. AN ATTENDANT SURFACE LOW PRESSURE
SYSTEM WAS OBSERVED VIA SFC WIND FIELDS OVER EASTERN IOWA, WITH
A WARM FRONT LIFTING NORTHWARD AHEAD OF IT ALONG THE I-80
CORRIDOR. SOME BREAKS IN THE CLOUD COVER HAS SUPPORTED
DESTABILIZATION TO THE TUNE OF 1000-1500 J/KG OF SBCAPE PER
RAP13/SPC MESOANALYSIS. PRIMARILY A TORNADO THREAT WILL
CONTINUE DUE TO THE PROXIMITY TO THE SURFACE LOW AND WARM FRONT,
WITH SOME MARGINAL LOW-LEVEL SHEAR OF AROUND 50 TO 150 M2/S2 OF
0-1 KM SRH. DAMAGING WINDS REMAIN A SECONDARY THREAT WITH ANY
STRONG/SEVERE STORMS.
AS WE HEAD INTO THE EVENING, LOW-LEVEL INSTABILITY IS EXPECTED TO
DECREASE WITH SUNSET, ALONG WITH THE SURFACE LOW EXITING THE REGION
TO THE EAST TONIGHT. DESPITE THIS, WE WILL KEEP SOME CHANCES (30-
60%) OF SHOWERS AND PERHAPS A FEW LINGERING THUNDERSTORMS AS THE
UPPER-LEVEL TROUGH LINGERS OVER THE UPPER MIDWEST. A PVA MAXIMA IS
PROGGED TO SWEEP THROUGH THE AREA LATE THIS EVENING THROUGH AFTER
MIDNIGHT TONIGHT, SUPPORTING THE ACTIVITY MAINLY ACROSS NORTHEASTERN
IA INTO NORTHWESTERN IL. SEVERE WEATHER ISN'T EXPECTED TONIGHT.
ALSO, EXPECT A COOL NIGHT TONIGHT, WITH LOWS IN THE MIDDLE
40S/LOWER 50S FOR MOST LOCATIONS. NOT A LOT OF CHANGE THROUGH
THE DAY WEDNESDAY, WITH LINGERING CHANCES (30-60%) OF SHOWERS
OVER OUR NORTHEASTERN AREAS. HIGHS EXPECTED TO WARM TO THE
MIDDLE 50S NORTH TO THE LOWER 60S SOUTH.
LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/
ISSUED AT 250 PM CDT TUE MAY 20 2025
WEDNESDAY NIGHT THROUGH THURSDAY
ASSESSMENT...VERY HIGH (>90%) CONFIDENCE OF COOLER THAN NORMAL
TEMPERATURES.
THE PROXIMITY OF THE UPPER LOW COMBINED WITH STEEP MID-LEVEL LAPSE
RATES WILL KEEP PLENTY OF CLOUDS ACROSS THE AREA ON WEDNESDAY WITH
CLOUDS SLOWLY BREAKING UP THURSDAY. AS A RESULT, TEMPERATURES WILL
BE WELL BELOW NORMAL.
WRAP AROUND RAIN WILL BE SEEN ACROSS THE AREA WEDNESDAY INTO
WEDNESDAY EVENING AS THE STORM SYSTEM SLOWLY EXITS THE AREA. THE
BEST CHANCES FOR RAIN WILL BE NORTH OF I-80 WITH LITTLE IF ANY RAIN
SOUTH OF AN OTTUMWA, IA TO GALESBURG, IL LINE.
RAIN MAY LINGER INTO LATE WEDNESDAY NIGHT ACROSS THE AREA.
ON THURSDAY, MID-LEVEL LAPSE RATES REMAIN QUITE STEEP WITH COLD AIR
ALOFT. THUS DIURNAL CLOUDS ARE EXPECTED TO DEVELOP DURING THE DAY
AND PRODUCE SOME ISOLATED SHOWERS, MAINLY NORTH OF I-80.
THURSDAY NIGHT THROUGH FRIDAY NIGHT
ASSESSMENT...HIGH (>80%) CONFIDENCE ON COOLER THAN NORMAL
TEMPERATURES
THE MODEL CONSENSUS HAS COOL CANADIAN HIGH PRESSURE MOVING THROUGH
THE MIDWEST BRINGING COOLER THAN NORMAL AND DRY CONDITIONS TO THE
AREA.
SATURDAY THROUGH MONDAY
ASSESSMENT...MEDIUM (40-60%) CONFIDENCE ON PRECIP FOR SATURDAY AND
SATURDAY NIGHT. LOW (<25%) CONFIDENCE BEYOND SATURDAY NIGHT
ALTHOUGH THERE ARE DIFFERENCES IN THE DETAILS, THE GLOBAL MODELS
GENERAL SHOW BOUNDARIES, EITHER AT THE SURFACE OR ALOFT, THAT A
STORM SYSTEM WILL FOLLOW THROUGH THE MIDWEST SATURDAY/SATURDAY
NIGHT. SUBTLE TIMING DIFFERENCES BETWEEN THE SOLUTIONS HAVE RESULTED
IN SOMEWHAT LOWER POPS BUT THE MODEL CONSENSUS OF 20-50 PERCENT RAIN
CHANCES LOOK REASONABLE THIS FAR OUT.
THE BIGGER QUESTIONS IS WHAT HAPPENS SUNDAY INTO MONDAY.
THE CMC SLOWS THE SATURDAY SYSTEM TO A CRAWL AND HAS IT LINGERING
OVER THE MIDWEST FOR THE REMAINDER OF THE HOLIDAY WEEKEND. THE ECMWF
AND ICON MODELS ARE ESSENTIALLY DRY SUNDAY INTO MONDAY.
THE GFS/UKMET HAVE A VERY WEAK SYSTEM RIGHT ON THE HEELS OF THE
SATURDAY SYSTEM THAT HAS RAIN FOR SUNDAY/SUNDAY NIGHT. THE UKMET HAS
A TERTIARY SYSTEM, ALBEIT VERY WEAK, IN THE CYCLONIC FLOW ALOFT
MOVING THROUGH THE AREA ON MONDAY PRODUCING SOME RAIN WHILE THE GFS
IS DRY.
SOME BUT CERTAINLY NOT A MAJORITY OF THE ENSEMBLE MEMBERS FROM THE
GLOBAL MODELS LINGER PRECIPITATION SUNDAY THROUGH MONDAY ACROSS THE
AREA.
THUS THE MODEL CONSENSUS IS BIASED BY THE CMC/UKMET SOLUTIONS AND
THE ENSEMBLES OF THE GLOBAL MODELS IN KEEPING 30-40 PERCENT RAIN
CHANCES SUNDAY THROUGH MONDAY ACROSS THE AREA.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 645 PM CDT TUE MAY 20 2025
WIDESPREAD MVFR TO LIFR CEILINGS ARE IN PLACE ACROSS THE AREA
AS A STORM SYSTEM CONTINUES TO SLOWLY LIFT NORTHEASTWARD ACROSS
IOWA AND INTO LOWER GREAT LAKES. PERIODS OF SHOWERS ARE
POSSIBLE THROUGH THE EVENING WITH POTENTIAL FOR PERIODS OF LIFR
CEILINGS AND MVFR VISIBILITIES. IFR TO LIFR CEILINGS WILL
PREVAIL THROUGH THE PERIOD AS LOW CLOUDS LINGER ACROSS THE
REGION IN THE WAKE OF THIS STORMS. AS THE SURFACE LOW DEPARTS
THE AREA TONIGHT, SURFACE WINDS ARE FORECAST TO TURN MORE TO THE
NORTH WITH SPEEDS AROUND 10 KNOTS. AFTER 12 UTC ON WEDNESDAY,
NORTH WINDS WILL INCREASE TO 10 TO 15 KNOTS WITH GUSTS UP TO 25
KNOTS.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...SCHULTZ
LONG TERM...08/SCHULTZ
AVIATION...COUSINS
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