ACUS02 KWNS 170601
SWODY2
SPC AC 170600
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Oct 17 2025
Valid 181200Z - 191200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE ARKLATEX
TO THE CENTRAL MISSISSIPPI AND LOWER OHIO VALLEYS...
...SUMMARY...
Scattered severe thunderstorms are possible Saturday across parts of
the Ark-La-Tex, Ozarks, mid Mississippi and lower Ohio Valleys.
Damaging winds, a few tornadoes and hail are possible.
...Synopsis...
A broad upper trough over the central US is forecast to deepen
throughout Saturday as several peripheral shortwave features
coalesce over the central MS Valley. The most prominent of these
features will start the period over the southern Rockies before
phasing with the broader trough across the southern Plains Saturday
night. A powerful 100+ kt mid-level jet exiting the central
Rockies/High Plains will round the base of the consolidated trough
helping to rapidly deepen a surface low over the OH Valley and Lower
Great Lakes. A cold front with strong southerly flow ahead of it
will sweep eastward from the OH/MS Valleys into the Mid South
overnight supporting scattered to numerous thunderstorms.
...Ohio Valley to the Ozarks...
Mid-level ascent with an embedded perturbation will expand over the
slow-moving cold front initially positioned from the Ozarks to the
Lower Great Lakes and OH Valley early Saturday. Southerly flow will
allow for substantial moistening as low to mid 60s F surface
dewpoints move northward across MO/IL, into western KY and OH and
eventually Lower MI. Continued low-level warm advection should
result in scattered to numerous thunderstorms along the front by mid
afternoon into the evening. While buoyancy should be limited
(500-1000 J/kg) owing to increasing storm coverage and cloud cover,
elongated mid/upper-level hodographs with largely unidirectional
shear will favor some potential for organized short line segments.
This activity should generally become more organized into the
afternoon/evening as the cold front strengthens and surges eastward
as the upper trough and surface low organize. This will support a
risk for damaging gusts and perhaps a couple embedded tornadoes
should a more coherent QLCS develop and persist overnight.
...Southern Plains to the Mid MS Valley...
Ahead of the primary southern stream shortwave trough, rich
low-level moisture will advect northward across parts of TX/OK into
the central and lower MS Valley. While some potential exists for
early morning convection to modulate the environment, current
guidance suggests diurnal destabilization (MLCAPE ~ 2000 J/kg) is
likely ahead of surface trough trailing the developing low farther
north. Scattered thunderstorm development is expected in the
afternoon from northern AR into eastern OK and North TX with the
potential for supercell structures capable of damaging gusts and
hail initially.
With time, the surface cold front over the southern Plains should
begin to surge eastward as the advancing shortwave trough phases
with the strengthening upper trough. Vertical shear will increase
substantially as the mid-level jet streak noses into the Mid South
fostering strong low-level mass response. The cold front will likely
outpace and overtake the surface trough and ongoing convection
supporting rapid upscale growth into a squall line across the
central MS Valley Saturday evening into the early overnight hours.
While uncertainty about the degree of instability given the
overnight timing remains, strengthening low-level wind fields and
mid 60s F dewpoints may delay boundary-layer decoupling long enough
to support a damaging wind and embedded tornado threat overnight as
the QLCS moves eastward.
..Lyons.. 10/17/2025
$$
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