146
AWUS01 KWNH 161855
FFGMPD
MOZ000-IAZ000-KSZ000-NEZ000-162253-
MESOSCALE PRECIPITATION DISCUSSION 1093
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
254 PM EDT TUE SEP 16 2025
AREAS AFFECTED...IOWA, NORTHWESTERN MISSOURI, FAR NORTHEASTERN
KANSAS
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 161853Z - 162253Z
SUMMARY...ISOLATED TO SCATTERED THUNDERSTORM ACTIVITY WAS
DEVELOPING AND MOVING SLOWLY ACROSS THE DISCUSSION AREA. LOCAL
RAIN RATES REACHING 2 INCHES/HR ARE POSSIBLE IN A FEW SPOTS,
POTENTIALLY CAUSING ISOLATED FLASH FLOODING.
DISCUSSION...RADAR/SATELLITE IMAGERY DEPICTS DEVELOPING
THUNDERSTORMS ACROSS CENTRAL IOWA GENERALLY ALONG AN AXIS FROM
NEAR MASON CITY SOUTH-SOUTHWESTWARD TO WEST OF DES MOINES. MORE
ISOLATED CONVECTIVE ACTIVITY WAS ATTEMPTING TO DEEPEN INTO FAR
NORTHEASTERN KANSAS. STRONG INSOLATION/SURFACE DESTABILIZATION
HAS ENABLED DEEPER CONVECTION TO BECOME SUSTAINED ALONG A SUBTLE
SURFACE CONFLUENCE IN THAT VICINITY. MEANWHILE, PW VALUES
EXCEEDING 1.5 INCH AND MINIMAL CONVECTIVE INHIBITION IS
CONTRIBUTING TO EFFICIENT RAINFALL PROCESSES, WITH LOCAL 1-1.5
INCH/HR RAIN RATES ALREADY NOTED WEST OF DES MOINES. BOTH FORCING
ALOFT AND KINEMATICS WERE WEAK, RESULTING IN SLOW-MOVING ACTIVITY
THAT SHOULD PERSIST FOR A FEW HOURS THIS AFTERNOON.
THE LONGEVITY OF ONGOING ACTIVITY (AND EXTENT OF FLASH FLOOD RISK)
SHOULD GENERALLY BE TIED TO THE PERSISTENCE OF SUBTLE LOW-LEVEL
CONFLUENCE ACROSS THE REGION TODAY. MODELS SUGGEST THAT STORMS
SHOULD PERSIST FOR AT LEAST ANOTHER 3-5 HOURS OR SO. GROUND
CONDITIONS ARE A BIT ON THE DRY SIDE (MODEST SOIL MOISTURES PER
NASA SPORT DATA) AND RELATIVELY HIGH FFG THRESHOLDS (AROUND 2
INCHES/HR). EACH OF THESE FACTORS, PLUS QUESTIONS ABOUT THE
SPATIAL EXTENT OF CONVECTIVE COVERAGE THROUGH 23Z/6P CDT) ARE ALL
SUGGESTIVE OF AN ISOLATED FLASH FLOOD THREAT AT BEST.
COOK
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...DMX...EAX...OAX...TOP...
ATTN...RFC...KRF...MSR...NWC...
LAT...LON 43259428 43209326 41879333 40659384 39569404
39419477 39829600 42129526
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