Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 21 2025 06:05:13

AWUS01 KWNH 210603
FFGMPD
ILZ000-MOZ000-IAZ000-211200-

Mesoscale Precipitation Discussion 0770
NWS Weather Prediction Center College Park MD
202 AM EDT Mon Jul 21 2025

Areas affected...much of MO

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

Valid 210600Z - 211200Z

Summary...1-2"/hr rainfall rates to continue with localized
repeating and backbuilding leading to additional totals of 2-5"
(atop 3-6"+ that has already fallen). Scattered to numerous
instances of flash flooding likely (with locally significant, life
threatening impacts expected).

Discussion...Intense deep convection has rapidly grown upscale
late tonight from west-central IL through east-central MO, driven
significantly in part by strong low-level frontogenesis and
convergence. The mesoscale is also characterized by SBCAPE of
500-3000 J/kg, PWs of 1.8-2.5" (between the 90th percentile and
all time max record, per ILX sounding climatology), and effective
bulk shear of 20-30 kts. While both the intensity and residence
time of locally extreme heavy rainfall have likely peaked (with
2"+ hourly amounts and over 1" in 15-min in the past 1-2 hours,
per MRMS estimates), some forward propagation of convection has
only just begun and this favorable environment for heavy rainfall
will continue to support 1-2"/hr rates (with localized repeating
and backbuilding) for at least 3-6 more hours.

Latest hi-res CAMs are in relatively good agreement with the
evolution of convection over the next 6 hours, suggesting
additional localized 2-5" amounts (at least partially overlapping
with areas already having realized 3-6"+ totals over the past 6
hours). These amounts should also occur in close proximity to the
Saint Louis metro area, which is particularly sensitive to flash
flooding impacts. Given the scale of reports of flash flooding
already ongoing, scattered to numerous instances of flash flooding
are likely to continue (with locally significant, life threatening
impacts).

Churchill

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6X1HOXYXS0ptJvSvMcaPTkFt64hRNg3T4LNmTG1pjkDRkzRI7YP11gEwthghvziWjj3g=
N9OBySAnm25_AU24KB0p394$  for graphic product...

ATTN...WFO...DMX...DVN...EAX...ILX...LSX...PAH...

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

LAT...LON   40789420 40769264 40499071 39608932 39028809=20
            37938834 37728991 38639210 38969365 39769451=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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