Subj : MESO: Mesoscale Discussion 0412
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Mar 31 2023 22:31:01

ACUS11 KWNS 312230
SWOMCD
SPC MCD 312230=20
ILZ000-WIZ000-IAZ000-MOZ000-MNZ000-010030-

Mesoscale Discussion 0412
NWS Storm Prediction Center Norman OK
0530 PM CDT Fri Mar 31 2023

Areas affected...Eastern Iowa...Western Illinois...Northeast
Missouri...Extreme Southwest Wisconsin

Concerning...Tornado Watch 93...

Valid 312230Z - 010030Z

CORRECTED FOR WORDING DISCUSSION PARAGRAPH

The severe weather threat for Tornado Watch 93 continues.

SUMMARY...Tornadoes, very large hail and widespread wind damage will
be likely across the northern and eastern part of WW 93 over the
next 2 to 4 hours. The greatest severe threat will exist from
eastern Iowa into western Illinois and northeastern Missouri.

DISCUSSION...The WSR-88D high-resolution radars in Iowa at Des
Moines and Davenport show four severe line-segments ongoing in
eastern Iowa, with several tornadic supercells ongoing. These storms
are located to the east of a 986 mb surface low, along an
north-to-south axis of moderate instability. A 90 to 110 knot
mid-level jet is translating quickly northeastward toward the Mid
Mississippi Valley at near 50 knots. The left exit region of the
mid-level jet is moving across eastern Iowa and western Illinois,
and is creating strong deep-layer shear and enhanced lift, favorable
for intense supercells. Ahead of the mid-level jet, a 50 to 60 knot
low-level jet will strengthen over the next few hours across the mid
Mississippi Valley. This feature will maintain low-level shear very
favorable for tornadic supercells. RAP forecast soundings increase
0-3 km storm-relative helicity into the 400 to 450 m2/s2 range
across northwestern Illinois early this evening, suggesting the
tornado threat will increase there. Over the next few hours, the
most favorable corridor for long-track high-end tornadoes will be
from eastern Iowa into northwest Illinois.

In addition to the tornado threat, several swaths of wind damage
will be likely with bowing line segments. This potential could
increase over the next few hours, especially if the line segments
can accelerate in forward speed. Due to the steep mid-level lapse
rates, strong deep-layer shear and relatively cold temperatures
aloft, supercells will also likely be prolific hail producers.

...Broyles.. 03/31/2023

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!-cy1fnDSqpS6ov58M-ZTLDj68kOvEufRaG54so1uiLcMlWcTguf2HHuVpBVXWoie8hzdLZ11L=
4YwrE3k_eEuidufkiI$  for graphic product...

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

LAT...LON   43509145 43459235 43049300 42379330 41539294 40509210
            39409175 38939104 39069027 39368963 39758929 40448910
            41308936 42368995 43249070 43509145=20


=3D =3D =3D
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