Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 28 2025 08:22:22

AWUS01 KWNH 280820
FFGMPD
WIZ000-ILZ000-IAZ000-281300-

Mesoscale Precipitation Discussion 0816
NWS Weather Prediction Center College Park MD
419 AM EDT Mon Jul 28 2025

Areas affected...Far Eastern IA...Northwest to Central IL

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

Valid 280819Z - 281300Z

SUMMARY...Increasing coverage of heavy showers and thunderstorms
early this morning may pose a threat for at least isolated areas
of flash flooding.

DISCUSSION...The very early morning GOES-E IR satellite imagery
along with radar shows areas of showers and thunderstorms
developing and expanding in coverage across portions of far
eastern IA and adjacent areas of northwest IL. This activity is
forming generally out ahead of an overnight MCS which continues to
drop steadily southward across large areas of central IA.

Mid-level vort/shortwave energy associated with the MCS appears to
be helping to increase the southwest low-level flow across eastern
IA and into central/northern IL. This increase in warm air
advection and corresponding moisture/instability transport is
allowing for an arc of convection to gradually expand in coverage
and this trend is likely to continue at least going into the early
morning hours.

In fact, an analysis of the MLCAPE values across eastern IA and
into western IL suggest the convection is forming in a somewhat
elevated fashion along and just ahead of a pseudo warm front ahead
of the upstream MCS. Some MLCAPE values across eastern IA are on
the order of 4000 J/kg and suggestive of very strong instability.
Meanwhile, a moist airmass characterized by PWs near 1.75 inches
is noted, and the combination of this moisture and instability
will support high rainfall rates that may reach 2 inches/hour.

Some localized cell-training concerns will be possible across
portions of far eastern IA and down through at least northwest IL
over the next few hours. Some rainfall totals of 2 to 4+ inches
will be possible, and this may drive at least some concerns for
isolated flash flooding. This may include some urban flash
flooding impacts as well.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5DqWDGRsNiIh3KdY5qEDRevKEYnwGvP8sn-w5N9_DGgZYv1ESNBAD924hau6BOeTTSWA=
Ar4kSE5bH89BpIXKUGzFUTU$  for graphic product...

ATTN...WFO...ARX...DVN...ILX...LOT...MKX...

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

LAT...LON   42699069 42588961 42188895 41378848 40658833=20
            40318866 40128915 40428994 41319067 41849101=20
            42349108=20

=3D =3D =3D
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