AWUS01 KWNH 261229
FFGMPD
MIZ000-INZ000-ILZ000-MOZ000-IAZ000-261725-

Mesoscale Precipitation Discussion 0804
NWS Weather Prediction Center College Park MD
829 AM EDT Sat Jul 26 2025

Areas affected...northeastern MO, southeastern IA, north-central
IL, northern IN and southwestern MI

Concerning...Heavy rainfall...Flash flooding possible

Valid 261225Z - 261725Z

SUMMARY...A flash flood threat will continue across portions of
the Midwest over the next 3-5 hours, but overall waning is
expected. Peak rainfall rates of 1-2 in/hr and isolated additional
maxima of 2-3 inches are expected.

DISCUSSION...Radar imagery at 12Z showed thunderstorms stretched
from northern MO into southeastern IA and northwestern IL. Several
small-scale forward propagating linear segments were embedded
within the convective axis from northern MO to the southern IA/IL
border, to the north of a remnant west-east outflow boundary over
MO/IL/IN. An MCV was estimated over southeastern IA, ahead of a
low to mid-level vorticity max/shortwave positioned across
west-central IA, with movement toward the ENE. GOES East DMV and
RAP analyses showed a 70-80 kt jet max over southern WI, with
divergence and diffluence aiding lift across IA/MO/IL within its
right-entrance region.

A 20-30 kt low level jet extended from eastern KS into northern
MO, helping to feed the ongoing convective complex which has
produced peak MRMS-derived hourly rainfall in the 1-2 inch range
within areas of training over the past 2 hours. The flash flood
threat is expected to continue as forcing for ascent shifts
eastward, but there are some mixed signals for the continuation of
flash flood concerns downstream. Weakening of the low level jet
and the departure of the upper jet streak to the north will have
an overall weakening effect to the ongoing area of thunderstorms.
However, the environment remains very moist (2.06" PW on the 12Z
ILX sounding) and increasing instability along and south of the
outflow boundary in IL/western IN with the onset of daytime
heating may result in some flare ups of new convective development
late this morning into the early afternoon to the east of ongoing
activity, promoting the potential for training within
unidirectional southwesterly flow. An additional 2-3 inches will
be possible on an isolated basis through 17Z with a continued risk
of flash flooding.

Otto

ATTN...WFO...DMX...DVN...EAX...GRR...ILX...IND...IWX...LOT...
LSX...

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

LAT...LON 42178579 41518543 40918612 40538713 40098873
39579110 39299318 39559396 39989403 40239376
40519314 40779250 41309159 41649026 42028790

$$
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