Subj : MESO: Heavy Rain - floodi
To   : All
From : Mike Powell
Date : Sat Apr 15 2023 17:49:00

AWUS01 KWNH 152146
FFGMPD
ILZ000-MOZ000-160300-

Mesoscale Precipitation Discussion 0189
NWS Weather Prediction Center College Park MD
545 PM EDT Sat Apr 15 2023

Areas affected...central/southern MO into central/southern IL

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

Valid 152144Z - 160300Z

Summary...1 to 2.5 inches of rain will be possible from portions
of central/southern MO into south-central IL over the next few
hours. Localized flash flooding will be possible with peak
rainfall rates of 1 to 2 in/hr.

Discussion...Thunderstorms were ongoing at 2120Z, just ahead of a
cold front that stretched from western IL into southwestern MO and
just north of a low level convergence axis, enhanced by
thunderstorm outflow that extended from just north of TBN to just
south of STL. The environment was characterized by precipitable
water values just over 1 inch and MLCAPE of 1000-2000 J/kg (per
SPC mesoanalysis data), resulting in MRMS-derived rainfall rates
of 1-2 in/hr at times.

Steering flow was southwest to northeast, or quasi-parallel to the
pre-frontal convergence axis which could allow for some training
and/or repeating of storms. Short term forecasts from the RAP
support enhancement to lift leading up to and just beyond 00Z as
an 80-100 kt jet streak develops across the MO/IA border with
divergence and diffluence aloft increasing over the mid-MS Valley.
Thunderstorms are expected to continue to follow the cold front as
it tracks east through 03Z, with the orientation of the cold front
somewhat normal to storm movement limiting the degree of flash
flooding. However, where storms align from southwest to northeast,
initially along the convergence axis in MO, and possibly later on
as thunderstorms moving into IL, brief training could allow for a
quick 1.5 to 2.5 inches of rain. 3-hr flash flood guidance of 1.5
to 2.0 inches for a large portion of the discussion area in MO and
IL could be exceeded in a couple of locations, resulting in
localized flash flooding.

Otto

ATTN...WFO...ILX...LSX...PAH...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   40218949 39818879 38958871 38108935 37039150 
            36809325 37609310 38009270 39199137 39849053 
            

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