401
ACUS01 KWNS 042001
SWODY1
SPC AC 041959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Fri Apr 04 2025

Valid 042000Z - 051200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ARKLATEX TO
SOUTHEAST MISSOURI...

...SUMMARY...
Several clusters of severe storms are expected from central Texas
across the ArkLaTex and into the lower Ohio Valley through tonight.
The greatest threat for tornadoes, large hail and damaging winds
will be from the ArkLaTex across western Arkansas into southeast
Missouri, including potential for strong to potentially intense
tornadoes.

...20z Update...
Morning and early afternoon observations show the frontal zone
gradually expanding north/northwest from the ArkLaTex to the mid MS
and lower OH Valleys. As strong mid-level flow overlaps with the
destabilizing air mass, several clusters of severe thunderstorms
appear are ongoing and are likely to continue, with a risk for all
hazards into tonight. Minor changes were made to the northern end of
the outlook area, in accordance with the latest
observations/guidance.

...ArkLaTex...
The primary surface-based convective band, forming along and east of
the surface front from northeast TX to southern AR should continue
intensify with several supercells likely emerging and tracking
through the MDT Risk Corridor. Additional, more isolated storms are
possible within a pre-frontal confluence axis and across the warm
sector this afternoon. The 18z SHV and LZK soundings show very
favorable thermodynamic profiles, with considerable low-level
hodograph curvature (ESRH 330-500 m2/s2) and deep-layer shear
supportive for intense supercells. With observed and forecast STP of
5+, several tornadoes, some of which may be strong to intense appear
likely into this evening. The primary limiting factor for higher
probabilities continues to be the more meridional and front parallel
flow near the baroclinic zone. The numerous storm interactions
should favor upscale growth as a QLCS gradually emerges later this
afternoon/evening.

...Lower OH and TN valley...
Weak convective development within the broader warm sector has been
noted early this afternoon across parts of TN and southern KY.
Strong diurnal heating amid 70s F surface dewpoints and steep
low-level lapse rates may allow these storms to slowly intensify
through the afternoon. Displaced from the deeper ascent near the
front, storm coverage and organization are expected to be somewhat
less than farther southwest. Still, 40+ kt of effective shear with
modestly large clockwise curved hodographs suggests some potential
for supercellular activity, with a risk for damaging gusts, hail,
and a couple tornadoes.

The greater severe concern is expected later tonight as upscale
growth from the convection over the MS Valley moves eastward. A QLCS
with embedded supercellular elements appears likely across parts of
western KY and TN into central KY and southern OH. Damaging gusts
and tornadoes are expected. Given the robust destabilization now
ongoing south of the warm front, have opted to expand the SLGT and
the ENH farther east across KY and TN for a damaging wind and
tornado threat.

...West TX...
Model guidance continues to show a broad area of elevated convection
developing after dark. Significant hail and some damaging winds are
possible with elevated supercells tracking north from the Edwards
Plateau toward the Red River tonight.

..Lyons.. 04/04/2025

.PREV DISCUSSION... /ISSUED 1129 AM CDT Fri Apr 04 2025/

...ArkLaTex to the lower OH Valley through tonight...
An amplified midlevel trough over the Southwest will move slowly
eastward, while embedded/subtle speed maxima eject northeastward
over the southern Plains.  Additionally, large-scale ascent will be
enhanced within the right-entrance region of the upper jet over the
upper Midwest.  At the surface, a baroclinic zone is expected to
move northward today across AR/western TN/KY in response to a weak
wave developing northeastward from northeast TX toward northwest AR
this afternoon and southeast MO tonight.  The depth of the cool air
at LZK diminished substantially from 00z to 12z, which supports
northward mixing of the front and warm sector this afternoon.

Within the surface warm sector, a very moist air mass is in place
with low 70s boundary-layer dewpoints beneath midlevel lapse rates
of 7.5-8.5 C/km.  Daytime heating in cloud breaks will contribute to
MLCAPE of 2000-3000 J/kg and weakening convective inhibition by
early-mid afternoon, when thunderstorm development is expected both
along the surface front and in the open warm sector.  Storm
development will be most concentrated along the front where ascent
will be focused and training storms are likely.  More isolated
storms will also be possible farther east in the warm sector from AR
into western TN/KY by mid-late afternoon.  Deep-layer vertical
shear/hodograph length will be favorable for supercells, with
substantial low-level hodograph curvature (effective SRH near or
above 300 m2/s2, especially near and just southeast of the front in
AR).  Given the fairly strong low-level shear and a relatively moist
environment in the low levels, supercells will be capable of
producing a few strong (EF2-EF3) tornadoes this afternoon into this
evening in the Moderate risk area.  Otherwise, very large hail to
baseball size and damaging gusts will be possible with the
supercells and embedded/organized storm clusters training along the
baroclinic zone.  North of the front, organized storms will be
capable of producing large hail and occasional damaging gusts.

...Edwards Plateau to north TX late tonight...
Similar to the previous two nights, another round of elevated
thunderstorms is expected near and after 06z from the Edwards
Plateau into north TX and perhaps southeast OK.  The storm
environment will be favorable for both elevated supercells with very
large hail and bowing clusters with some potential for damaging
winds to the surface.

$$