582
FXUS63 KDVN 180837
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
337 AM CDT SUN MAY 18 2025
KEY MESSAGES
- ACTIVE PATTERN SET TO DEVELOP LATE TONIGHT THROUGH WEDNESDAY
WITH PERIODS OF SHOWERS AND STORMS. HIGH LIKELIHOOD OF
RAINFALL OF GREATER THAN 1 INCH (60-90% CHANCE) WITH LOCALLY
HEAVY RAINFALL GREATER THAN 2 INCHES POSSIBLE (30-60% CHANCE).
- CONDITIONAL SEVERE WEATHER THREAT (LEVEL 1/2 OUT OF 5)
MODULATED BY THE LOCATION OF A WARM FRONT EXISTS FOR LATE
MONDAY PM/NIGHT, WITH LARGE HAIL AND DAMAGING WINDS THE
PRIMARY THREATS.
SHORT TERM /THROUGH TONIGHT/
ISSUED AT 333 AM CDT SUN MAY 18 2025
SURFACE HIGH PRESSURE RIDGING WILL BE THE DOMINANT FEATURE
TODAY PROVIDING FOR MUCH LIGHTER WINDS AND VERY PLEASANT
TEMPERATURES. WE HAVE SOME STRATUS THAT HAS WORKED INTO AREAS
NORTH OF HWY 30 EARLY THIS MORNING. WHILE TO THE SOUTH, WE HAVE
SOME DEBRIS CIRRUS OFF WEAK CONVECTION ACROSS PORTIONS OF
MISSOURI STREAMING ACROSS THE SOUTH HALF AS WELL, FOLLOWED BY
SOME MID LEVEL WARM ADVECTION CLOUDINESS IN THE WAKE ACROSS FAR
SOUTHERN IOWA AND NORTHWEST MISSOURI. IN GENERAL, THESE CLOUD
AREAS WILL LINGER FOR A WHILE THIS MORNING, BUT THEREAFTER
ANTICIPATE A GRADUAL EROSION INTO THIS AFTERNOON ALLOWING FOR
INCREASING SOLAR INSOLATION. HIGHS ARE FORECAST WITH THIS IN
MIND, AND RANGE FROM AROUND 70 NORTH TO THE UPPER 70S IN THE FAR
SOUTH. EXACT HIGHS WILL ONCE AGAIN BE MODULATED BY CLOUD COVER.
TONIGHT, CAMS SUPPORT A BACKDOOR /LAKE MICHIGAN ENHANCED COLD
FRONT MOVING WESTWARD ACROSS MUCH OF THE AREA BETWEEN 03Z AND
10Z. THIS WILL BRING A SHIFT IN WINDS TO EAST/NORTHEAST ALONG
WITH SOME GUSTS TO AROUND 25 MPH. A DECENT TEMPERATURE CONTRAST
IS LIKELY RANGING FROM THE LOWER 40S IN PARTS OF NORTHWEST
ILLINOIS TO THE MID 50S ACROSS THE FAR SOUTHERN PORTIONS OF THE
SERVICE AREA. LATE TONIGHT WILL ALSO BRING OUR FIRST CHANCE OF
RAINFALL (30-60%), PARTICULARLY ACROSS THE SOUTH/WEST PORTIONS
AIDED BY REMNANT DEBRIS FROM MCS ALONG WITH A VEERING NOCTURNAL
LLJ AND ISENTROPIC ASCENT. THE WARM FRONT LOOKS TO BE WELL
DISPLACED TO OUR SOUTH, AND SO THE FEELING IS THIS WILL BE
MAINLY STRATIFYING RAIN/SHOWERS WITH SOME EMBEDDED THUNDER.
LONG TERM /MONDAY THROUGH SATURDAY/
ISSUED AT 333 AM CDT SUN MAY 18 2025
THE CHANCE (30-60%) FOR RAIN/SHOWERS AND EMBEDDED THUNDER
POTENTIAL WILL PERSIST MONDAY MORNING, WITH THE HIGHEST
CHANCES ACROSS THE SOUTHWEST HALF OR SO, WHILE FAR NORTHEAST
SECTIONS COULD STAY DRY.
THE NEXT ROUND OR WAVE OF PRECIPITATION AND REALLY THE MAIN
SLUG IF YOU WILL IS SET FOR MAINLY MONDAY NIGHT INTO TUESDAY,
WITH THE RAMPING SYNOPTIC SCALE LIFT /UPPER DIFFLUENCE AHEAD
OF AN APPROACHING UPPER LOW. THIS IN TANDEM WITH STRONG
MOISTURE TRANSPORT/ADVECTION WITH PWATS SURGING TO NEAR 1.5
INCHES (ABOVE 90TH PERCENTILE FOR ALL DVN RAOBS PER SPC
SOUNDING CLIMATOLOGY) WILL SET THE STAGE FOR SHOWERS AND
STORMS WITH BOTH A HEAVY RAINFALL THREAT AND POTENTIAL
SEVERE WEATHER THREAT. THE SEVERE THREAT IS CONDITIONAL AND
MODULATED IN LARGE PART BY THE POSITION OF A WARM FRONT.
BUT, CURRENTLY THIS POSITION MAY BE CLOSE ENOUGH TO BRING A
THREAT FOR A FEW SEVERE STORMS WITH LARGE HAIL, AND ALSO
GUSTY WIND THREAT WITH SHALLOW STABLE LAYER PENDING ROBUST
UPDRAFTS. THE MAIN TIMING WOULD BE FROM 4P MONDAY TO 12A
TUESDAY, BUT CAN'T RULE OUT SOME ISOLATED MAINLY HAIL THREAT
PERSISTING OVERNIGHT MONDAY NIGHT/EARLY TUESDAY MORNING.
THE UPPER LOW WILL SHIFT SLOWLY ACROSS THE REGION TUESDAY
AFTERNOON INTO WEDNESDAY KEEPING CLOUDS AND RESIDUAL
SHOWER CHANCES ALONG WITH A FEW STORMS POSSIBLY. INTENSITY
SHOULD DIMINISH DURING THIS TIME AS WELL WITH MAINLY
BROAD WEAKER LIFT.
STRENGTH OF FORCING SUGGESTS AT LEAST RAINFALL ACCUMULATING TO
NEAR THE PWAT, OR ROUGHLY 1 TO 2 INCHES WIDESPREAD BETWEEN 06Z
MONDAY AND 12Z WEDNESDAY, BUT WITH CONVECTION AND PERSISTENT
MOIST CONVEYOR AND SLOW MOVING SYSTEM FOR REPETITIVE ROUNDS IT'S
POSSIBLE TO SEE LOCALLY HIGHER AMOUNTS OF 3+ INCHES. LATEST NBM
SHOWS PROBABILITIES OF 30-60% FOR >2 INCHES OF RAIN OVER 72
HOUR PERIOD ENDING 12Z WEDNESDAY WITH THE HIGHEST PROBABILITIES
SOUTH OF I-80. MUCH OF THE AREA IS IN ABNORMAL DRYNESS TO
MODERATE DROUGHT PER THE LATEST U.S. DROUGHT MONITOR AND GIVEN
THE SOIL CAPACITY TO HANDLE A DECENT RAINFALL THIS SHOULD BE
MOSTLY A BENEFICIAL RAIN. BUT CAN'T RULE OUT SOME LOCALIZED
WATER ISSUES, ESPECIALLY WITH ANY HIGH RAINFALL RATES
CONVECTIVELY ENHANCED AND/OR REPEATED HEAVY RAIN OR CONVECTION
WITH THE MAIN CONCERN SHOULD THIS OCCUR IN ANY URBAN AREAS.
OTHERWISE, MOSTLY WITHIN-BANK RISES ON CREEKS, STREAMS AND
RIVERS IS ANTICIPATED FROM THIS RAINFALL. ONE THING TO STILL
KEEP IN MIND IS THE LIKELIHOOD OF MCS ACTIVITY ALONG THE WARM
FRONT, AND WHETHER OR NOT THIS CONVECTION WILL HAMPER THE
POLEWARD PROGRESS OF THE RETREATING WARM FRONT AND SUBSEQUENTLY
ALTER WHERE THE HEAVIER RAINS OCCUR.
LOOKING AT TEMPERATURES MONDAY AND TUESDAY, THIS FRONT SEEMS
LIKELY TO HOLD UP JUST SOUTH OF OUR CWA IN NORTHERN MISSOURI,
WITH A GUARANTEE OF CLOUDS AND EAST WINDS NORTH OF IT.
TEMPERATURES MAY BE QUITE COOL, ESPECIALLY NORTH OF I-80 WHERE
LAKE ENHANCED LOW LEVEL FLOW IS EXPECTED WITH A TRAJECTORY OF
LAKE MICHIGAN AIR FROM THE NORTHEAST/EAST. COMBINED WITH BOUTS
OF RAINFALL, THE WEATHER APPEARS QUITE UNPLEASANT MONDAY THROUGH
WEDNESDAY, WITH HIGHS POTENTIALLY AS COOL AS THE 50S FOR SOME
LOCATIONS. THERE IS A WIDE DISTRIBUTION OF HIGH TEMPERATURES IN
THE NBM IN THIS PERIOD, AND THE TIGHT GRADIENT ALONG AND NORTH
OF THE FRONT SEEMS THE CULPRIT. WE WILL CONTINUE TO REFINE
TEMPERATURES MONDAY-WEDNESDAY WITH MORE DETAIL IN THE COMING
DAYS, BUT FOR NOW, THE NBM REMAINS A BEST FIT WITH MID 50S NORTH
TO LOWER 70S FAR SOUTH.
THURSDAY INTO NEXT WEEKEND, PLEASANT TEMPERATURES ARE FORECAST
AS THE UPPER LOW SHIFTS TOWARDS THE EASTERN CONUS. THOUGH A FEW
SHOWERS COULD OCCUR IN NORTHWEST FLOW, THE DRY AIR IN PLACE
WOULD KEEP THE THREAT FOR RAINFALL LOW. HIGHS IN THE 60S TO 70S
ARE FORECAST.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 1130 PM CDT SAT MAY 17 2025
PREDOMINANTLY VFR EXPECTED THROUGH THE PERIOD, ALTHOUGH AT THE START
OF THE PERIOD THROUGH MID-MORNING SUNDAY WE'LL SEE SOME LOWER CLOUDS
AND MVFR CEILINGS DIP SOUTHWARD INTO THE CID AND DBQ TERMINALS. THESE
SHOULD LIFT/ERODE AND RETURN TO VFR AT CID AND DBQ BY 15Z-18Z. CONFIDENCE
ON THESE MVFR CEILINGS REACHING MLI IS TOO LOW AT THIS TIME FOR ANY
MENTION, AND THEY ARE NOT EXPECTED AT BRL. WINDS WILL BE MUCH LIGHTER
AROUND 10 KTS FROM A NORTHERLY DIRECTION. LATE IN THE TAF PERIOD AND
JUST BEYOND THERE'S INDICATIONS OF A BACKDOOR LAKE ENHANCED FRONT PUSHING
THROUGH THE TERMINALS FOLLOWED BY GUSTY EASTERLY WINDS OF 15-25 KT.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...MCCLURE
LONG TERM...MCCLURE/ERVIN
AVIATION...MCCLURE
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