Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed Jun 25 2025 22:17:29

AWUS01 KWNH 252217
FFGMPD
WIZ000-MNZ000-IAZ000-260415-

Mesoscale Precipitation Discussion 0515
NWS Weather Prediction Center College Park MD
616 PM EDT Wed Jun 25 2025

Areas affected...Northern Iowa, Southeast Minnesota, and
west-central Wisconsin

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

Valid 252215Z - 260415Z

SUMMARY...Showers and thunderstorms are expected to continue
through early tonight across portions of the Upper Midwest, while
also containing intense rainfall rates up to 2"/hr and the
potential for totals up to 4". These rainfall amounts may lead to
scattered instances of flash flooding.

DISCUSSION...A low pressure system was analyzed across southern
Minnesota at 21z with an attached warm front extending eastward
into western and southern Wisconsin while a cold front extended
westward into southern South Dakota. Recent radar and satellite
observations depict numerous strong to severe thunderstorms in the
warm sector across southeastern Minnesota and into northern Iowa,
with moderate to locally heavy stratiform rain north of the low
pressure system and attached warm front. These thunderstorms are
estimated to contain maximum hourly rainfall rates up to 2"/hr in
localized spots and are moving generally east-northeastward.
Instability is abundant across Iowa with SBCAPE values of
4000-5000 J/kg as broad southerly flow helps place this
instability perfectly in the inflow of ongoing storms. PWs also
remain high and between 1.9-2.2" per SPC's mesoanalysis page,
which would place it above the 90th climatological percentile.

21Z HRRR and 20Z experimental RRFS differ somewhat in the exact
location of heaviest amounts, but both agree on up to 4" of total
rainfall from these storms. 6-hr FFG are around 2-4" so this
plants a scenario where isolated to scattered instances of flash
flooding are possible. The upwind propagation vectors do have a
northwesterly component so while brief training of storms is
ongoing across northern Iowa and southeast MN, these storms should
become more progressive as we get into the late evening.

Snell

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!65jnbVfWIvUprhnJ7gDLT2GDH9E1dVTXxeqSxEdMauFfvzZzh480LJP-Mjeq0rNg7d2k=
8PucvUm-zwAwydU_7yZVQlM$  for graphic product...

ATTN...WFO...ARX...DMX...FSD...GRB...MKX...MPX...

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

LAT...LON   45339175 44889028 44228951 43518968 42859122=20
            42449294 42219429 42299518 42769530 43409449=20
            44209363 45209285=20

=3D =3D =3D
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