AWUS01 KWNH 071106
FFGMPD
ILZ000-MOZ000-IAZ000-071530-

Mesoscale Precipitation Discussion 0880
NWS Weather Prediction Center College Park MD
705 AM EDT Thu Aug 07 2025

Areas affected...Southwest/South-central
Iowa...North-central/Northeast Missouri...Far Western Illinois...

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

Valid 071105Z - 071530Z

SUMMARY...Warm advective training and upwind propagation may
support localized increased duration of 2"/hr rates. Spots of
3-4" are possible over the next few hours resulting in possible
flash flooding.

DISCUSSION...Hi-resolution CAM guidance is not
resolving/assimilating the strength of the early morning southwest
to northeast LLJ being about 10 knots too slow. So while there is
some sufficient capping remaining in the analysis fields
(espcially further east), the strength of isentropic ascent
orthogonal to the instability gradient has been strong enough to
break through the limited cap with elevated thunderstorm
development feeding on sufficient 1500-2000 J/kg (per modestly
steep mid-level lapse rates) of MUCAPE. CIRA LPW does show a bit
of drier air further west aloft, but surface moisture is more
limited through the Ozark Plateau, resulting in a narrower core of
moisture across eastern KS into southern IA with values of 1.5
increasing to about 1.75" pooling along the isentropic ascent
plane. This is increasing localized rain rates of 1.75-2"/hr.

Deep layer steering also quickly veers a bit more northwesterly,
resulting in west to east cell motions, yet eastern edge of deeper
layer moisture/instability and solid 500-1000 thickness ridging
support southward propagation. Combine that with stronger inflow
allowing for westward propagation, lowering of cloud bases nearing
the warm front across KS/west-central MO, this is some forward
slowing of cells into northern MO allowing for mergers to occur.
These mergers may allow for some short-term increase in
rates/totals (over 2-2.25"/hr) as noted in Annapose county over
the last hour or so. RADAR trend suggest, increased
convergence/mergers are possible north and west as cold pool may
be further steepening the isentropes further east, increasing the
upwind convergence in the nearer term. As such, spots of 3-4"
may start accumulating in the next few hours and with 3hr FFG in
the 2-3" range, localized flash flooding is considered possible.

Without support of CAMs, confidence is low in placement but more
on the timing of eventual weakening. Watching VWP observations in
the region will be key, but seems even a drop of 5-10kts in the
925-850mb layers will be very important toward this trend, though
there has be a slow erosion of usptream cu noted in SWIR over the
last few hours too.

Gallina

ATTN...WFO...DMX...DVN...EAX...LSX...OAX...

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

LAT...LON 42099466 41749309 40639122 39629130 39489235
39909333 40729473 41199522 41709545 42019519

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