278
FXUS63 KDVN 241523
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
1023 AM CDT THU APR 24 2025
..HYDROLOGY UPDATE
KEY MESSAGES
- SHOWERS AND STORMS WILL ONCE AGAIN LINGER INTO THE EARLY MORNING
HOURS TODAY.
- ONE MORE SLOW MOVING ROUND OF SHOWERS AND STORMS ARE EXPECTED
FROM TONIGHT THROUGH FRIDAY MORNING. SEVERE STORMS ARE NOT
ANTICIPATED.
- SEVERE STORMS ARE POSSIBLE EARLY NEXT WEEK.
SHORT TERM /THROUGH FRIDAY/
ISSUED AT 302 AM CDT THU APR 24 2025
SIMILAR TO THE PAST FEW MORNINGS, THE OVERNIGHT SHOWERS AND
THUNDERSTORMS ARE IN A WEAKENING STAGE AND MOVING WELL EAST OF THE
INITIATION POINT AS OF 2 AM. OUTFLOW FROM THE STORMS IN CENTRAL IOWA
HAVE PUSHED THE CONVERGENCE FROM THE STATIONARY FRONT A BIT SOUTH,
NOW IN SOUTH CENTRAL IOWA THROUGH NORTHERN ILLINOIS. THIS IS ONLY
THE SURFACE BOUNDARY, AS THE FRONT ALOFT REMAINS IN NORTHERN IOWA
INTO SOUTHERN WISCONSIN. THE MAIN ACTION ALONG THE FRONT TODAY
APPEARS TO BE SETTING UP NORTH AND WELL WEST, WELL, AFTER THE
EVOLUTION OF THE FESTERING ACTIVITY ON THE NORTHEAST NOSE OF THE
WEAK LLJ, WHICH IS AIMED INTO OUR NORTHERN CWA, AND SHOULD AT LEAST
OFFER SCATTERED SHOWERS AND WEAK STORMS IN THE NORTHERN 1-2 COUNTIES
THROUGH SUNRISE, SOMETHING MODELS DON'T HANDLE WELL, BUT HAS BEEN
THE CASE THE LAST 2 MORNINGS.
AFTER THIS ACTIVITY DECAYS COMPLETELY, TODAY WILL SEE THE FRONT LIFT
NORTH, RESULTING IN A WARM, BUT NOT OVERLY HUMID DAY. DEW POINT
VALUES LOOK TO REMAIN IN THE 50S AS WE LACK FRONTAL CONVERGENCE TO
SEE HIGHER VALUES. HIGHS IN THE MID 70S NORTH TO LOWER 80S CENTRAL
AND SOUTH ARE EXPECTED, WITH DRY WEATHER HOLDING IN NEARLY THE
ENTIRE AREA THROUGH MID AFTERNOON. BY LATE AFTERNOON, THE
APPROACHING COLD FRONT AND MID LEVEL SHORT WAVE IS EXPECTED TO
INITIATE STORMS OVER WESTERN AND CENTRAL IOWA, WHICH COULD QUICKLY
EVOLVE EAST/NORTHEAST, REACHING OUR WESTERN COUNTIES IN THE 5 -7 PM
TIME FRAME. WITHOUT MUCH SHEAR AND STRONG FORCING TODAY, ONLY AN
ISOLATED DOWNBURST OR HAIL SEEMS THE THREAT, AND THAT'S MAINLY WEST
OF OUR AREA.
TONIGHT, STORMS WILL GRADUALLY SHIFT EAST, WITH SUPPORT FROM THE MID
LEVEL SHORT WAVE AND SLOWLY ADVANCING COLD FRONT. THIS FRONT IS NOT
EXPECTED TO ARRIVE IN OUR AREA UNTIL LATE TONIGHT, AND EXIT OUR AREA
BY LATE FRIDAY MORNING, WHICH PROBABLY MEANS THE CONVECTION WILL
DECAY BEFORE MOVING THROUGH THE AREA TONIGHT. THIS HAS RESULTED IN A
LOWERED POPS (30-40%) IN THE EASTERN CWA, WHILE WESTERN AREAS REMAIN
~80-90%.
FRIDAY MORNING, THE FRONT WILL SLOWLY WORK THROUGH THE AREA, WITH
POPS REMAINS IN THE 50-70% RANGE THROUGH THE MORNING, BEFORE
DROPPING CONSIDERABLY EARLY IN THE AFTERNOON, AND DRY BY LATE DAY.
QPF FROM TONIGHT THROUGH FRIDAY APPEARS TO BE 0.5 TO 1.0 INCH WEST,
TO UNDER 0.25 IN THE EAST. THE SLOW MOVEMENT OF STORMS MAY ALLOW FOR
ISOLATED HEAVY RAINFALL AMOUNTS IN OUR WESTERN AREAS FROM LATE
AFTERNOON THROUGH THIS EVENING.
LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/
ISSUED AT 302 AM CDT THU APR 24 2025
PLEASANT, COOLER AIR IS ON THE WAY FOR FRIDAY NIGHT THROUGH SUNDAY,
AS HIGH PRESSURE MOVES INTO THE REGION, ALLOWING FOR LOWS TO DROP TO
THE UPPER 30S TO MID 40S AGAIN, WITH HIGHS IN THE 60S TO LOW 70S
THIS WEEKEND.
SUNDAY AFTERNOON, LOW OPS REMAIN IN THE BLENDED FORECAST, BUT WITH
LITTLE BOUNDARY LAYER MOISTURE, THE MOISTURE TRANSPORT ALOFT
SHOULDN'T REALLY ARRIVE UNTIL AFTER DARK, AND THAT APPEARS
AIMED INTO MN FOR NOW. OVERNIGHT INTO MONDAY MORNING, SOME
ELEVATED SHOWERS AND STORMS APPEAR MORE LIKELY, WITH BOTH
MOISTURE TRANSPORT BEGINNING TO AIM INTO OUR AREA, AND
CONCEPTUAL CONVECTIVE EVOLUTION SUPPORTS THE MN ACTIVITY
DROPPING SOUTHEAST BY MORNING TOO.
THE CONVECTIVE EVOLUTION INTO EARLY WEEK IS NO LONGER AS
CONSISTENTLY FORECAST BY MODELS INTO TUESDAY, WITH BOTH FRONTAL
PLACEMENT GREATLY VARIED, AS WELL AS THE UPPER TROF POSITION. FOR
NOW, THE 00Z GFS AND EC SHOW LESS PHASING OF THE NORTHERN ROCKIES
AND SOUTHERN ROCKIES TROF MONDAY. WE WILL WAIT FOR SPC'S EXTENDED
OUTLOOK BEFORE ADDRESSING THIS FARTHER. BUT A RISK WILL NEED TO BE
WATCHED IN THIS PERIOD, AS STRONGER WINDS ALOFT ARE FORECAST WITH
THIS FRONTAL PASSAGE, THAN THE STORMS IN THE PAST FEW DAYS.
WARM WEATHER CAN BE EXPECTED AHEAD OF THIS FRONTAL SYSTEM, MONDAY
AND TUESDAY, WITH HIGHS IN THE 70S AND 80S, FOLLOWED BY COOLER
WEATHER IN THE 60S FOR WEDNESDAY.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 621 AM CDT THU APR 24 2025
THOUGH SHOWERS ARE 20 MILES NORTHWEST OF CID AND DBQ SINCE 08Z
TODAY, THEY ARE NOT EXPECTED TO REACH EITHER SITE THIS MORNING.
VFR WEATHER LOOKS TO LAST ALL DAY WITH WARM CONDITIONS AND EAST
TO SOUTHEAST WINDS THROUGH THE AFTERNOON. AN ISOLATED STORM IS
POSSIBLE BETWEEN 20-23Z BUT THIS IS FAR FROM CONFIDENT ENOUGH TO
PUT IN THE TAF FORECASTS. GREATER CONFIDENCE IS THAT A PERIOD OF
IFR/MVFR IS EXPECTED OVERNIGHT TONIGHT (07-12Z FRIDAY), AS A
COLD FRONT BRINGS SHOWERS AND THUNDERSTORMS TO THE AREA. MOST
HOURS SHOULD BE RAIN, WITH A PERIOD OF 1-2 HOURS OF THUNDER.
HYDROLOGY
ISSUED AT 1022 AM CDT THU APR 24 2025
WITH RECENT BOUTS OF HEAVY RAINFALL, AND POSSIBLY MORE TONIGHT WITH
INCREASED RUN-OFF ESPECIALLY IN THE UPPER BASINS OF THE IOWA, WAPSI,
AND CEDAR RIVERS, THESE RIVERS WILL LIKLEY EXPERIENCE SIGNIFICANT IN-
BANK RISES. SOME POINTS AND STRETCHES OF THESE RIVERS MAY ALSO
SURPASS ACTION STAGE AND EVEN THE FLOOD STAGE INTO THE WEEKEND. BUT
THERE IS STILL SOME UNCERTAINTY WITH RESPECT TO TONIGHT'S
PLACEMENT OF ADDITIONAL HEAVY RAINFALL AMOUNTS, AS WELL AS
ASSOCIATED EXTENT OF RUN-OFF. SINCE THERE IS STILL SOME TIME TO
ASSESS THESE FACTORS BEFORE THE POTENTIAL CRESTS OCCUR, HAVE
ISSUED RIVER FLOOD WATCHES FOR THE WAPSI AT DE WITT, AND THE
IOWA RIVER AT MARENGO.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...ERVIN
LONG TERM...ERVIN
AVIATION...ERVIN
HYDROLOGY...12
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