556
FXUS63 KDVN 191823
AFDDVN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
123 PM CDT MON MAY 19 2025
KEY MESSAGES
- WET PATTERN THROUGH MIDWEEK. HEAVIEST RAINFALL OCCURS
TONIGHT INTO TUESDAY. HIGH LIKELIHOOD OF WIDESPREAD
RAINFALL AMOUNTS GREATER THAN 1 INCH (70-95% CHANCE) WITH
LOCALLY HEAVY RAINFALL GREATER THAN 2 INCHES LIKELY (50-70%)
FOR PARTS OF THE AREA.
- CONDITIONAL SEVERE WEATHER THREAT (LEVEL 1/2 OUT OF 5)
MAINLY FOR THIS EVENING FOR SOUTHERN PARTS OF THE AREA, WITH
LARGE HAIL THE PRIMARY HAZARD AND DAMAGING WINDS A SECONDARY
HAZARD.
- STRONG GRADIENT WINDS OF 45+ MPH ARE POSSIBLE LATE TONIGHT
INTO EARLY TUESDAY.
- CONDITIONAL SEVERE THREAT (LEVEL 1 OUT OF 5) FOR PARTS OF THE
AREA TUESDAY AFTERNOON AND EARLY EVENING, WITH TORNADOES AND
DAMAGING WINDS THE PRIMARY THREATS.
SHORT TERM /THROUGH TUESDAY NIGHT/
ISSUED AT 323 AM CDT MON MAY 19 2025
BANDS OF CONVECTION ARE NOTED EARLY THIS MORNING ACROSS PARTS OF
NE/KS WITHIN AN OVERLAP OF UPPER DIFFLUENCE, STRONG MOISTURE
ADVECTION AND INSTABILITY AHEAD OF A LOW OVER THE ROCKIES.
THE CONVECTION IS WEAKENING/STRATIFYING AS IT SHIFTS EAST OF THE
MISSOURI RIVER VALLEY AND ENCOUNTERS A MORE STABLE, DRIER AIRMASS.
WE'LL SEE ISENTROPIC ASCENT INCREASE THIS MORNING ATTENDANT TO
THE LOW LEVEL JET THAT WILL FOSTER SHOWER ACTIVITY FOR PARTS OF
THE AREA THIS MORNING - GREATEST COVERAGE FAVORING WEST/SOUTH
PORTIONS OF THE SERVICE AREA. SOME SHOWERS WILL LIKELY PERSIST
INTO THIS AFTERNOON WITH EVEN A FEW RUMBLES OF THUNDER POSSIBLE,
AS THE WARM ADVECTIVE PROCESSES CONTINUE. ASIDE FROM SOME SPOTTY
0.25 INCH+ RAIN AMOUNTS (AREA FAVORED FOR THESE BEING WEST/SOUTH),
ANY RAIN LOOKS TO BE MOSTLY VERY LIGHT OF A TRACE TO AROUND 0.1 INCH.
EASTERLY WINDS WILL TURN GUSTY TODAY WITH LOW LEVEL WIND PROFILES
SUPPORTIVE OF SOME GUSTS 20-30+ KT. MOST AREAS SHOULD SEE HIGHS
IN THE 60S, BUT WITH WANING CONVECTION LATER TODAY AND ANY CLOUD
BREAKS/THINNING THERE IS THE POTENTIAL FOR SOME 70S WHERE THIS
OCCURS.
LONG TERM /WEDNESDAY THROUGH SUNDAY/
ISSUED AT 323 AM CDT MON MAY 19 2025
AN UPPER LEVEL TROUGH WILL CONTINUE TO PROGRESS FROM THE ROCKIES
ACROSS THE NORTHERN AND CENTRAL PLAINS BY 12Z TUESDAY.
INCREASINGLY DIFFLUENT FLOW ALOFT AND STRONG MOISTURE ADVECTION
WILL DEVELOP INTO OUR REGION LEADING TO A BURGEONING OF SHOWERS
AND SOME STORMS TONIGHT THAT WILL CONTINUE IN BANDS/WAVES INTO
TUESDAY. PWATS SURGING OVER 1.5 TO NEAR 1.8 INCHES WILL SUPPORT
HEAVY RAINFALL AND WIDESPREAD 0.5 TO 2 INCH AMOUNTS FROM TONIGHT
THROUGH THE DAY ON TUESDAY WITH THE HEAVIEST FAVORED IN OUR
WEST AND SOUTHWEST SERVICE AREA. GIVEN THE AMPLE SOIL CAPACITY
DUE TO ABNORMALLY DRY TO MODERATE DROUGHT CONDITIONS, WE'RE
EXPECTING MOST IF NOT ALL OF THIS TO BE ABSORBED WITH NOT MUCH
ISSUE. THAT BEING SAID, CAN'T TOTALLY RULE OUT LOCALIZED WATER
ISSUES IF AN AREA SEES REPEATED HEAVY RAIN OR CONVECTION, WITH
THE MAIN CONCERN BEING IF THIS WERE TO OCCUR IN AN URBAN CENTER.
THERE IS A CONDITIONAL SEVERE WEATHER THREAT THIS EVENING/TONIGHT.
DEEP LAYER SHEAR IS MORE THAN SUFFICIENT FOR UPDRAFT ORGANIZATION,
BUT LOCATION OF THE WARM FRONT WILL BE KEY TO WHAT THOSE THREATS
MAY BE. CURRENT INDICATIONS ARE THAT THE WARM FRONT WILL LIKELY
BE FAR ENOUGH SOUTH TO WHERE ANY CONVECTION WILL BE ELEVATED AND
THUS HAIL WOULD APPEAR TO BE THE PRIMARY THREAT. BUT, WIDESPREAD
CONVECTION AND COMPETING UPDRAFTS AND RAPID MOISTENING COULD LIMIT
HAIL THREAT TO MAINLY SUB-SEVERE IF ANY. SHOULD THE WARM FRONT
COME FURTHER NORTH AND BE IN CLOSER PROXIMITY TO THE SOUTHERN
COUNTIES, THEN COULDN'T RULE OUT SOME WIND POTENTIAL WITH A THINNING
STABLE LAYER. SPEAKING OF WIND, CONCERNS ARE GROWING A BIT FOR THE
POTENTIAL OF SOME MESOSCALE GRAVITY WAVE INDUCED BOUTS OF HIGH
WINDS TONIGHT (45 TO 55+ MPH). CONCEPTUALLY THE PATTERN SUPPORTS
THIS POTENTIAL WITH AN EMBEDDED SHORTWAVE TROUGH AND ACCOMPANYING
MID/UPPER LEVEL SPEED MAXIMA (AND IMPRESSIVE JET DIFFLUENCE)
LIFTING UP ACROSS THE REGION, WHILE LOCATED AHEAD OF A
STRENGTHENING/DEEPENING SURFACE LOW (NEED ISALLOBARIC COMPONENT TO
HELP GENERATE GRAVITY WAVES) WITH FAVORABLE STRONG INVERSION DEPTHS
AROUND 1-2KFT AGL. NAMNEST AND HRRR MODEL SURFACE WIND GUST FIELDS
APPEAR TO HINT AT THIS POTENTIAL WITH SOME POCKETS OF HIGHER GUSTS
(40+ KT) THIS EVENING WELL NORTH OF THE WARM FRONT, THAT EXPAND IN
COVERAGE LATE TONIGHT AFTER 06Z-12Z PARTICULARLY NORTH OF I-80.
IN ADDITION, 00Z HREF PAINTBALL PLOT OF WINDS >30 KT AND DBZ >20
HINT AT THIS POTENTIAL AS WELL BUT IT'S MORE WEST OF THE MISSISSIPPI
RIVER. BOTTOM LINE, COULD BE A PERIOD OF RATHER WINDY AND POTENTIAL
ADVISORY CRITERIA FOR PARTS OF THE AREA TONIGHT INTO EARLY TUESDAY
MORNING THAT WILL NEED TO BE MONITORED.
TUESDAY IS A DAY WE'RE MONITORING CLOSELY FOR SEVERE WEATHER POTENTIAL,
AS THE SURFACE LOW AND TRIPLE POINT ARE POSITIONED ACROSS PARTS OF
THE AREA. CURRENTLY SPC HAS PLACED A MARGINAL OR LEVEL 1 OUT OF 5 RISK
FOR AREAS ROUGHLY SOUTH/EAST OF THE QC METRO. IT'S A CONDITIONAL
SEVERE THREAT DEPENDENT UPON SUFFICIENT HEATING/DESTABILIZATION, BUT
ONE THAT POTENTIALLY COULD HARBOR A SNEAKY SETUP FOR TORNADOES
POSSIBLY. RAP AND HRRR SHOW CORRIDORS OF 0-3KM CAPE OF 100-200 J/KG,
WHICH COULD SUPPORT BETTER OVERLAP BETWEEN HORIZONTAL VORTICITY
AND UPDRAFT INITIATION AND ESSENTIALLY ALLOW A MESOCYCLONIC CIRCULATION
TO HAVE A CLOSER INTERACTION WITH THE SURFACE /LOW-LEVEL STRETCHING OF
NEAR SURFACE VORTICITY/ TO FOSTER A TORNADO RISK. OVERALL, A SURFACE
BASED THREAT COULD MATERIALIZE VIA WIND OR TORNADO, WITH HAIL POTENTIAL
LOOKING LOW DUE TO DEEP SATURATION AND WEAKER LAPSE RATES ALOFT.
STAY TUNED FOR UPDATES ON THIS POTENTIAL FOR TUESDAY MID AFTERNOON
THROUGH EARLY EVENING. WHILE MORE WIDESPREAD HEAVY RAINS ARE NOT
EXPECTED BEYOND TUESDAY MORNING, WE WILL SEE SLOW MOVING CONVECTION
FOSTERING A LIKELIHOOD OF NARROW CORRIDORS OF ADDITIONAL HEAVY RAIN.
FALLING ON ALREADY WET GROUND THIS WOULD NEED TO BE WATCHED FOR A RISK
OF LOCALIZED FLASH FLOODING.
WEDNESDAY INTO THURSDAY, SCATTERED SHOWERS LOOK TO LINGER ACROSS PARTS
OF THE AREA WITH RESIDUAL LIFT FROM THE SLOW MOVING UPPER LOW.
THEN BY LATE WEEK WE'LL START TO DRY OUT AND SEE MODERATING TEMPERATURES
HEADING INTO THE MEMORIAL DAY HOLIDAY WEEKEND. WE'LL SEE SOME RAIN
CHANCES RETURN THOUGH OVER THE WEEKEND AHEAD OF THE NEXT TROUGH AND
ONSET OF WARM, MOIST ADVECTION.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 120 PM CDT MON MAY 19 2025
STRONG EAST WINDS WILL CONTINUE THROUGH TONIGHT, AS LOW LEVEL
FLOW REMAINS EASTERLY, NORTH OF THE WARM FRONT IN MISSOURI.
PERIODS OF SHOWERS AND THUNDERSTORMS WILL SWEEP OVER THE AREA
THROUGH TUESDAY AND BEYOND, WITH THE MOST WIDESPREAD ACTIVITY
MID EVENING THROUGH THE OVERNIGHT AND UNTIL NOON TUESDAY.
SPORADIC MVFR CIGS ARE ALREADY OCCURRING TODAY IN CENTRAL INTO
EASTERN IOWA, AND WILL CONTINUE TO DROP TO IFR OVERNIGHT. ONCE
LOW CONDITIONS SET IN OVERNIGHT, THEY WILL REMAIN LOW THROUGH
THE DAY TUESDAY. EAST WINDS MAY OCCASIONALLY REACH 35+KT ON
GUST THROUGH NOON TUESDAY.
DVN WATCHES/WARNINGS/ADVISORIES
IA...NONE.
IL...NONE.
MO...NONE.
SHORT TERM...MCCLURE
LONG TERM...MCCLURE
AVIATION...ERVIN
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