Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Apr 01 2023 01:15:05

AWUS01 KWNH 010114
FFGMPD
OHZ000-MIZ000-INZ000-ILZ000-010600-

Mesoscale Precipitation Discussion 0149...Corrected
NWS Weather Prediction Center College Park MD
914 PM EDT Fri Mar 31 2023

Corrected for typo in second paragraph

Areas affected...eastern IL, northern IN, northwest OH into
southern half of MI

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

Valid 010110Z - 010600Z

SUMMARY...A quick 1-2 inches of rain could produce localized areas
of excess runoff across portions of the Midwest over the next few
hours.

DISCUSSION...0045Z radar imagery noted several areas of strong
convection over the Midwest within the warm sector of an
approaching frontal cyclone. Frontogenetically enhanced
thunderstorms were oriented WNW to ENE across southern MI while a
SW to NE oriented convective line was located across central IL.
Lastly, a bowing segment was found just ahead of the cold front
over northern IL. 500-1500 J/kg of either surface based or
elevated instability was estimated from IL into IN and
southwestern MI with the 00Z ILX sounding showing ~800 J/kg
MLCAPE. Strong forcing for ascent was ongoing across the region,
aided by strongly divergent and diffluent flow aloft ahead of an
estimated 120-150 kt jet at 250 mb streak crossing the central
MO/IL border as of 00Z.

Storm motions have been racing toward the northeast between 40-60
kt, limiting any threat of prolonged heavy rain to segments of
convection that align with the mean wind, allowing hourly rainfall
of over 1 inch. As thunderstorms over IL continue to move off
toward the northeast, there could be additional development out
ahead of the advancing line of storms, supporting short term
training that could allow for a quick 1 to 2 inches of rain. Brief
alignment of existing line segments with the mean wind may also
support an inch of rain in less than 1 hour. The cold front is
forecast to quickly track to the east at around 50 kt, ending the
threat for additional heavy rain from west to east, and
instability just ahead of the cold front is expected to weaken as
it track east. Nonetheless, isolated areas of excess runoff will
be possible across portions of northern IN, southern MI and
northwestern OH which have 1-hr FFG of 1 to 2 inches.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6nQDJrKpoaGl8aaDrPFTsY2IKWIncg8OPFHybyIs6oRTg9ZHsEMBP0H4QyDym36kmNcj=
J9RA1ek68KMO-ydr6mhXSx0$  for graphic product...

ATTN...WFO...CLE...DTX...GRR...ILN...ILX...IND...IWX...LOT...

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

LAT...LON   43658399 43408300 42988266 42268282 40598431=20
            39598662 39368756 40048807 41138775 41848701=20
            42168655 42908600 43528486=20

=3D =3D =3D
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