AWUS01 KWNH 101040
FFGMPD
WIZ000-ILZ000-MNZ000-IAZ000-101500-

Mesoscale Precipitation Discussion 0892
NWS Weather Prediction Center College Park MD
639 AM EDT Sun Aug 10 2025

Areas affected...IA into/across MS Valley and southern WI

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

Valid 101039Z - 101500Z

SUMMARY...Scattered areas of flash flooding will continue to be
likely from central IA, east-northeastward into southern WI and
far northern IL. Training of heavy rain will produce peak hourly
rainfall of 2 to 3 inches along with additional totals of 2 to 4+
inches through 15Z.

DISCUSSION...Radar and infrared satellite imagery showed an MCV
over west-central IA, just ahead of another area of cyclonic
rotation along the NE/IA border...with movement toward the ENE.
Out ahead of these features, radar imagery showed scattered
thunderstorms extending eastward from the MCV into eastern IA,
southern WI and northwestern IL, to the north of a remnant outflow boundary/trough axis that extended from southern IA into northern
IL. Areas of embedded training contained MRMS-derived hourly
rainfall of 1-2 inches but with localized hourly rainfall of 2 to
3+ inches over the past 1-3 hours. Low level flow of 25-40 kt was
overrunning the boundary along with ascent ahead of the upstream
vortex and given a similar orientation of low level winds to the
somewhat weaker deeper layer mean wind, Corfidi vectors were
oriented into the inflow layer supporting areas of training and
backbuilding.

SPC mesoanalysis data from 10Z showed MLCAPE of 1000 to 2000+ J/kg
was in place from central IA into southern WI, along with PWATs
near 2 inches. Aloft, IA was within a favorable region for ascent
within the right-entrance region of a 110 kt speed max aloft over
northern MN. This environment is expected to sustain for at least
another 2-4 hours which will continue areas of training downstream
of the MCV/vorticity max's track toward the ENE. While the
mesoscale pattern across the Upper Midwest is rather complex at
the moment, there are indications that low level winds will begin
to weaken at least somewhat with the diurnal cycle through 15Z,
but some low level enhancement ahead of the MCV should remain.
Areas of training are expected to maintain a likely flash flood
threat through 14Z/15Z across the Upper Midwest with potential for
an additional 2 to 4+ inches in a few locations, but some
potential weakening of rainfall intensities will be possible near 15Z.

Otto

ATTN...WFO...ARX...DMX...DVN...GRB...LOT...MKX...MPX...

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

LAT...LON 44648957 44288792 43398776 42698882 41209061
41159441 42339497 44029263

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