813
AWUS01 KWNH 062155
FFGMPD
MOZ000-MNZ000-IAZ000-KSZ000-NEZ000-SDZ000-070353-

Mesoscale Precipitation Discussion 1216
NWS Weather Prediction Center College Park MD
554 PM EDT Sun Sep 06 2026

Areas affected...Portions of the Corn Belt into the Missouri River
Valley

Concerning...Heavy rainfall...Flash flooding likely

Valid 062153Z - 070353Z

SUMMARY...Scattered to numerous slow-moving thunderstorms, some
strong to severe, will lead to a continued flash flood threat for
portions of the Corn Belt down through the adjacent Missouri River
Valley. Rainfall rates between 2 to 3 inches per hour are possible
in the strongest thunderstorms.

DISCUSSION...Widespread heavy thunderstorm activity continues
across much of western Iowa up into neighboring South Dakota and
Minnesota this afternoon. Upper level setup remains favorable for
broad scale ascent within a diffluent region positioned over the
North-Central Plains to Upper Midwest thanks to the slow
progression of a strong upper trough navigating over the
Northwestern U.S. At the surface, intense low-level convergence is
occurring within a narrow corridor situated near and just east of
the Missouri River as a quasi-stationary front aligns north to
south between SD down into KS. A broad surface high over the Great
Lakes allows for a continued southeasterly flow on the western
fringes of the ridge, providing a more prevalent low-level
convergence signature in tandem with the stationary front in
place. Deep moisture advection and elevated theta_E`s continue to
align in parallel to the frontal placement with MUCAPE firmly
between 3000-5000 J/kg according to the latest RAP mesoanalysis
over northwest MO through much of western IA. The setup remains
favorable for scattered to widespread heavy convective development
within that corridor of elevated theta_E`s and PWATs bisecting the
region with much of the CAMs maintaining the posture into the
evening.

Convective modes will remain more pulse to multi-cellular
varieties, but the formidable instability axis and deep moist
profile lend to numerous strong to severe thunderstorms capable of
torrential rainfall rates and gusty winds that will exacerbate
flash flooding concerns where significant rainfall has already
occurred, and points further south as mid-level ascent becomes
more favored for areas of west-central IA down into northwestern
MO. Latest HRRR/RRFS combo is consistent in the signature of heavy
thunderstorm development within the narrow tongue of elevated
theta_E`s centered just east of the Missouri River. Rainfall rates
between 2-3"/hr are likely in the strongest cell cores and with
mean flow generally out of the north to north-northwest, cells
will train or slowly wander over the same areas leading to
localized totals exceeding 3 inches with some CAMs members showing
upwards of 6 inches plausible in the setup. Despite some modest
FFG`s over the region, rainfall rates and significant rainfall
totals will supersede majority of the antecedent dryness over the
area leading to a greater threat for flash flooding. Given the
current state of flash flood warnings already issued with the
environmental favorability continuing through the evening, flash
flooding is likely to continue to the aforementioned area.

Kleebauer

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...DMX...EAX...FSD...MPX...OAX...SGF...TOP...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   43649577 43619511 43509459 43149407 42379382
            41449364 40749345 39779338 38589337 38139408
            38269520 39689591 40939638 41689650 42169655
            42679662 43049667 43529640 43619606