Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Oct 24 2023 17:09:54

AWUS01 KWNH 241709
FFGMPD
MIZ000-WIZ000-MNZ000-242305-

Mesoscale Precipitation Discussion 1150
NWS Weather Prediction Center College Park MD
109 PM EDT Tue Oct 24 2023

Areas affected...southern MN into central WI and the southern U.P.
of MI

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

Valid 241706Z - 242305Z

Summary...Repeating rounds of heavy rain with periods of training
will pose a localized flash flood threat across portions of the
Upper Midwest through 23Z. Rainfall rates of 1-2 in/hr are
expected at times with localized 3 hour totals in excess of 2
inches.

Discussion...16Z surface observations showed a surface low along
the MN/WI border near RGK, with a quasi-stationary front extending
WSW and a weak warm front extending eastward through central WI.
Radar imagery showed a training axis of convection just north of
the warm front in central WI, containing MRMS-derived rainfall
rates peaking near 1.5 in/hr between STE and AUW. While hail may
be overinflating MRMS values somewhat, these values are close to
two local Wunderground stations reporting 1.3 to 1.4 in/hr ending
1635Z beneath the MRMS hourly max. Additional convection was noted
over portions of southern MN. These thunderstorms were being
forced by overrunning WSW flow at 850 mb between 25-35 kt just
south of the frontal boundary (sourced via area VAD wind plots).
Many of the storms were elevated within an environment containing
steep 700-500 mb lapse rates between 7-8 C/km, MUCAPE near 1000
J/kg and PWATs of 1.1 to 1.4 inches (16Z SPC mesoanalysis data).

A mid-upper level shortwave seen on water vapor imagery over
central SD is forecast by the RAP to advance ENE through the late
afternoon while shearing/weakening but still allowing for subtle
height falls across the Upper Midwest. Weak waves along the front
will aid in supporting increased ascent atop the frontal boundary
with unidirectional WSW flow oriented parallel to the front
supporting periods of training. Peak rainfall rates of 1-2 in/hr
are expected at times with localized 3 hour totals above 2 inches,
in excess of FFG for a majority of southern WI into central WI,
where an estimated 1-3 inches of rain has fallen over the past 48
hours.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8kQ6STJGevlLyOe2tyxgguSXe3C0F2hPOo7ZpNTMq7yOocccmcXufbf9cW_NfXpHZVQ1=
W91Re6hyaTZpcXBqV5E105o$  for graphic product...

ATTN...WFO...ARX...DLH...FSD...GRB...MPX...MQT...

ATTN...RFC...NCRFC...NWC...

LAT...LON   46268754 46188674 46048620 45638608 45138666=20
            44668731 44458894 44059009 43659155 43629408=20
            43899511 44539504 44969392 45389214 45969015=20
            46208869=20

=3D =3D =3D
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