Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Thu Mar 13 2025

Valid 141200Z - 151200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN MISSOURI...FAR SOUTHEAST IOWA...CENTRAL AND SOUTHERN ILLINOIS...FAR
WESTERN KENTUCKY...FAR NORTHWEST TENNESSEE...AND EXTREME NORTHEAST ARKANSAS...

...SUMMARY...
A regional outbreak of severe storms is expected across much of the
Mississippi Valley, eastward to the Lower Ohio and Tennessee Valleys
late Friday afternoon into Saturday morning. Widespread damaging
winds (some greater than 65 kt), several tornadoes (some strong),
and large hail will all be possible.

...Synopsis...

An intense cyclone will develop from the central Plains to the Upper
Midwest on Friday. As this system rapidly deepens, an intense jet
streak (100+ kt at 500 mb) will overspread the Ozarks and Mid-MS
Valley. Meanwhile, a large area covering much of the MS Valley
vicinity will see 850-700 mb southwesterly flow around 65-80 kt.
Southerly low-level flow will transport mid 50s dewpoints as far
north as IA/northern IL (decreasing with northward extent across the
Upper Midwest). Richer boundary layer moisture (60s F dewpoints)
will be confined to the Lower MS Valley and Deep South/TN Valley,
though near-60 F dewpoints may reach the MS/OH River confluence.
Rapidly developing convection is expected to develop by late
afternoon from near a surface low over eastern NE and arcing
east/southeast along a dryline into the Ozarks. Convection will
develop northeast across the Mid-MS valley, with additional storms
develop with southward extent into the Mid-South and TN Valley
during the nighttime hours.

...Mid/Upper Mississippi Valley to the Lower OH/TN Valleys...

Cold temperatures aloft near the main upper low will support steep
midlevel lapse rates. While boundary moisture will be modest, MLCAPE
up to 1000-1500 J/kg is possible. This will support rapid storm
development amid intense deep-layer shear. Heating ahead of the
dryline also will support some boundary layer mixing and steepening
of low-level lapse rates. As a result, a rapidly developing QLCS is
expected. Convection will shift east/northeast into the nighttime
hours. Given fast storm motion and the intensity of deep-layer flow,
swaths of significant wind gusts (greater than 65 kt) are
anticipated over a large part of the Mid-MS Valley. A gradual
weakening of convection is expected after midnight with north and
east extent.

With southward extent from parts of eastern MO/western IL into the
Mid-South, some potential for a mix of linear convection and
supercells appears possible. Vertical shear will support tornadoes
within linear convection. The environment will especially be
favorable for strong tornadoes with any supercells that develop.
This activity may develop a little later than initial convection
further north, with much of the threat being after dark from
east-central MO/west-central IL southward to western TN.

Given the intensity of maximum gusts expected, and widespread
coverage of damaging gusts, a Moderate risk (level 4 of 5) has been
included for portions of the Mid-MS Valley vicinity.

...MS/AL/TN Overnight...

Persistent southerly low-level flow will bring mid to possibly upper
60s F dewpoints northward into the TN Valley overnight. Neutral to
modest height falls are expected and a persistent, strong low-level
jet will overspread the region. Forecast soundings indicate very
favorable thermodynamic and kinematic profiles, which would support
intense supercells. Forcing mechanisms will be somewhat modest over
the region, which may limit convective coverage, and a somewhat more conditional risk. However, any storms that develop within this
environment overnight will pose a risk for strong tornadoes, large
hail and damaging gusts.

...Upper Midwest/Great Lakes vicinity...

The severe risk will become more marginal into MN/WI/MI. Strong deep
layer flow will overspread the region and any convection will pose a
risk of strong gusts. An additional risk for hail also will exist,
especially with any elevated convection near the warm front overnight.

..Leitman.. 03/13/2025

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