943
ACUS01 KWNS 240534
SWODY1
SPC AC 240532

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 AM CDT Tue Sep 24 2024

Valid 241200Z - 251200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
TENNESSEE AND OHIO VALLEYS INTO THE SOUTHERN APPALACHIANS. A FEW
STRONG/SEVERE STORMS ARE ALSO POSSIBLE OVER THE SOUTHERN PLAINS....

...SUMMARY...
Isolated to scattered severe thunderstorms are possible today across
portions of the Ohio and Tennessee Valleys into the central/southern
Appalachians. A few strong/severe storms are also possible across
portions of the southern Plains.

...Ohio and Tennessee Valleys to southern Appalachians...

Positive-tilt short-wave trough is ejecting east across the mid MS
Valley early this morning. This feature is gradually deamplifying as
it`s kicked downstream in advance of an upstream short-wave trough
that`s digging across the Plains. As a result, 500mb flow should
increase across the TN/OH Valley region, and high-level flow will
become increasingly diffluent. Early this morning, an elongated
corridor of convection continues ahead of this feature, extending
from southwest IN into southeast MO. Some form of this activity will
likely be ongoing at the start of the period, immediately ahead of
the front. While the early-day convection should not be particularly
robust, boundary-layer heating should aid destabilization,
especially south of the OH River where 0-3km lapse rates should
steepen by 18z allowing MLCAPE values to increase to 1000-2000 J/kg.
While deep-layer flow will be decidedly southwesterly, effective
shear will be more than adequate for sustaining longer-lived
clusters and even a few supercells. Forecast soundings suggest
convection should develop fairly early in the period as mid-level
lapse rates are poor, but convective temperatures will be breached
quickly with temperatures rising through the 70s to near 80F.
Primary concern with these storms will be damaging winds.

...Southern Plains...

Upper ridge is forecast to build east into the Rockies during the
day1 period, but this will allow a strong upper trough to dig
south-southeast across the Plains as a 500mb speed max translates
down the back side into western KS by 25/00z. Left exit region of
this feature will encourage large-scale ascent, and a weak surface
wave/low should evolve over southwest KS/northwest OK by early
afternoon. This evolution will result in strong boundary-layer
heating across the TX South Plains into northwest OK. Forecast
soundings suggest 0-3km lapse rates will approach dry adiabatic by
21z, and convective temperatures will be breached in the upper 80s
to near 90F. While LLJ is not expected to be particularly
noteworthy, profiles across northwest into central OK will favor
supercells as low-level flow will be decidedly southeasterly through
1km, and effective shear will be strong (50kt). Additionally, MLCAPE
values in excess of 1000 J/kg should support robust updrafts. Will
introduce low severe probabilities for hail/wind for supercells that
evolve during the mid-late afternoon. This activity will spread
south-southeast during the evening hours in advance of the digging
short wave. Will continue to monitor this region, but at this time
coverage of severe may not warrant higher probabilities.

..Darrow/Thornton.. 09/24/2024

$$