Mesoscale Precipitation Discussion 0807
NWS Weather Prediction Center College Park MD
1150 PM EDT Sat Jul 26 2025

Areas affected...Eastern MO...Central IL

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

Valid 270350Z - 270750Z

SUMMARY...Heavy showers and thunderstorms will tend to expand in
coverage over the next few hours. High rainfall rates and some
cell-training concerns may promote some instances of flash
flooding over the next few hours.

DISCUSSION...The late-evening GOES-E IR satellite is showing an
expansion of cooling convective cloud tops over eastern MO and
into portions of central IL. The convection is generally focused
in close proximity to a shearing mid-level vort center/trough axis
and is being aided by convergence along a weak low-level surface
trough/boundary.

MLCAPE values along this boundary are on the order of 2000 to 2500
J/kg, and this strong instability coupled with PWs near 2.25
inches will be conducive for supporting convection with high
rainfall rates capable of reaching 2 to 3 inches/hour.

A further expansion of convection is generally expected in the
near-term based on the satellite trends and also with some
increase in the low-level flow near this shearing vort energy and
the low-level trough.

Some of the latest radar trends and observational data suggest an
environment conducive for some cell-training over the next few
hours, and with such high rainfall rates, some of the storm totals
heading into the overnight time frame may reach 3 to 5 inches on a
localized basis. This will support a concern for at least some
instances of flash flooding as a result.

Orrison

ATTN...WFO...ILX...LSX...

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

LAT...LON   39848970 39758850 39198830 38858940 38659129
            39079174 39529122