399
ACUS03 KWNS 120731
SWODY3
SPC AC 120730

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0230 AM CDT Wed Mar 12 2025

Valid 141200Z - 151200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE MIDDLE MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY...

...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 early Saturday morning. All severe
hazards are possible, including swaths of intense winds and
tornadoes.

...MS/Lower OH/TN Valleys...

A large cyclone will rapidly intensify as it lifts northeast across
the central Plains to the Upper Midwest on Friday. A 100+ kt
southwesterly jet streak at 500 mb will overspread portions of the
Ozarks/Mid-MS Valley, while a 60-70 kt low-level jet overspreads
much the Mid-South and Mid-MS/Lower OH Valleys during the late
afternoon into the overnight hours. Northward extent of deeper Gulf
moisture (60s F dewpoints) will likely remain south of southeast
MO/southern IL/western KY, with more modest 50s F dewpoints
expanding northward into southeast MN/southern WI and eastward
toward the Lower OH Valley. Despite the more modest moisture across
the northern half of the outlook area, cold temperatures aloft will
support steep midlevel lapse rates and at least weak instability.

A strongly forced QLCS is expected to develop along a surface
dryline as the mid/upper jet impinges on the Ozarks vicinity by late
afternoon or early evening. Intense forcing and deep-layer wind
fields will maintain an organized QLCS into the nighttime hours.
Strong daytime heating and mixing of the boundary layer ahead of the
QLCS will further promote swaths of severe/damaging gusts, some of
which may be greater than 65 kt. While moisture will be somewhat of
a limiting factor, QLCS tornadoes also will be possible.

Convection may develop later across AR into the TN Valley/Deep
South. However, deeper Gulf moisture will be in place across this
region (possible mid/upper 60s F). This will support stronger
instability amid supercell wind profiles. Large-scale ascent will be
more subtle across this area, but sharpening of the dryline across
AR and low-level confluence should support convective development
during the evening. Initial supercells may grow upscale into a line
moving across portions of AR/TN/northern MS/AL. An attendant risk of
strong tornadoes and swaths of damaging/potentially significant wind
gusts is expected across the Mid-South with this activity.

A more conditional risk for overnight supercells exists across parts
northern/central MS/AL. The environment could support intense
supercells capable of producing large hail and strong tornadoes this
far south, but forcing mechanisms will be weak. Trends will be
monitored and future outlook adjustments may be needed.

..Leitman.. 03/12/2025

$$