SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0304 PM CDT Sat Mar 15 2025
Valid 152000Z - 161200Z
...THERE IS A HIGH RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
EASTERN MISSISSIPPI AND WEST CENTRAL ALABAMA...
...SUMMARY...
A tornado outbreak is ongoing across the central Gulf Coast States.
Numerous significant tornadoes, some of which should be long-track
and potentially violent, may continue into this evening. The severe
risk should spread across eastern Mississippi through the remainder
of the afternoon into the evening, and reach western parts of the
Florida Panhandle and Georgia tonight.
...20z Update...
Dangerous tornado outbreak is ongoing and expected to continue this
evening over the Southeast. The main change for the 20z outlook was
to expand the categorical High Risk a bit over southwestern AL and
southern MS, and trim out the severe areas west. A squadron of
intense tornadic supercells will continue east/northeast over
eastern MS, and much of western AL this afternoon and into the
evening. The strongest low-level theta-E advection is occurring
across southeastern MS and west/southwestern AL. Strong ascent and
intense low-level shear from a 60-70 kt low-level jet should
continue to focus a nearly optimal supercell/tornado environment
over this area through this evening.
Upscale growth into one or more bowing line segments will be
possible late this evening over eastern AL and western GA. Strong
shear will continue the risk for tornadoes along with damaging
gusts.
Over northern AL and southern TN, widespread convection has resulted
in a messy storm mode with embedded supercell structures. A strong
meso low (994 mb) will continue northeast along the MS River Valley
supporting impressive low-level shear (0-1 km SRH of 250-500 m2/s2)
despite the less favorable thermodynamics. Tornadoes (some strong)
and numerous damaging wind gusts are possible with the embedded
supercells and bowing segments as a more linear storm mode should
begin to emerge through this evening.
..Lyons.. 03/15/2025
.PREV DISCUSSION... /ISSUED 1134 AM CDT Sat Mar 15 2025/
...Southeast into the Tennessee Valley...
No changes have been made to the High Risk area across the
Southeast. Multiple supercells are ongoing late this morning across
southeast LA into MS, along and east of a convectively reinforced
baroclinic zone. A very favorable parameter space exists across the
Southeast for severe thunderstorms, which will likely help maintain
ongoing supercells and small line segments. Current expectations are
for the most favorable strong to intense tornado environment to
continue across MS this afternoon and evening, with moderate
instability and ample low-level and deep-layer shear already in
place. The tornado threat will spread eastward into AL and southern
TN this afternoon and evening, and eventually into parts of the FL
Panhandle, western/central GA, and eastern TN overnight in tandem
with an ejecting southern-stream shortwave trough and related
intense low-level jet. Both large hail and severe/damaging winds
will also be a threat with these supercells. Upscale growth into one
or more bowing line segments will be possible, especially with
northward extent into the TN Valley and eastward into GA, where
potentially numerous to widespread severe/damaging winds may occur.
Reference Mesoscale Discussions 199, 200, and 201 for more
information on the near-term severe threat across the Southeast.
...Southern Appalachians...
As an upper trough pivots east into the region late tonight, strong
low-level warm/moist advection will contribute to a gradually
destabilizing airmass. Despite weaker buoyancy with eastward extent
over northeast GA into the western Carolinas, very intense low to
mid-level flow will aid in maintaining a risk for a few supercells
and line segments into a more limited thermodynamic environment.
This will potentially yield a risk for damaging gusts and an
isolated tornado threat through early Sunday morning.
...Ohio Valley into Southern Great Lakes...
Guidance maintains a belt of strong 850 mb flow through midday,
before an intensification of the northern periphery of a low-level
jet extending from the central Gulf Coast into the Mid South
overspreads the region. Uncertainty remains regarding the magnitude
of destabilization behind earlier convective activity, and its
resultant effects on severe potential. Most guidance generally shows
only weak buoyancy (at or below 500 J/kg of MUCAPE), but some
airmass recovery in the wake of earlier thunderstorms may occur over
IN into OH and vicinity.
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