287
ACUS01 KWNS 252010
SWODY1
SPC AC 252009

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0309 PM CDT Sat May 25 2024

Valid 252000Z - 261200Z

...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR MUCH OF
OKLAHOMA...CENTRAL AND EASTERN KANSAS...SOUTHWEST AND SOUTH-CENTRAL
MISSOURI...AND FAR NORTHERN TEXAS....

...SUMMARY...
An outbreak of severe thunderstorms is possible from late afternoon
into tonight over parts of the central and southern Plains.  A few
long-lived supercells capable of intense tornadoes may occur.  Giant
hail and destructive wind gusts are also expected.

Expanded all outlook categories eastward across Missouri based on
increased confidence in multiple supercells across southern Kansas
congealing into a cluster during the overnight period. RAP forecast
soundings show extreme buoyancy (3500+ J/kg) continuing through the
overnight period amid robust low-level moisture and steep mid-level
lapse rates. A forward propagating cluster capable of severe wind
gusts and tornadoes is expected to persist through 12Z Sunday.

The only other change was to expand the moderate farther south into
north Texas based on recent observational trends. Numerous
supercells have formed west of this area and should persist as they
continue east into a high theta-e airmass. Large hail will be the
primary threat with an increasing tornado threat near 00Z as the
low-level jet intensifies.

No changes were made to the primary risk area. See MCD #954 for
additional discussion of the threat in this area.

..Bentley.. 05/25/2024

.PREV DISCUSSION... /ISSUED 1134 AM CDT Sat May 25 2024/

...Central/Southern Plains...
Overall, little change was made to the ongoing outlook with this
update, with the primary change being an eastward expansion of the
Enhanced/Level 3 Risk over portions of North Texas based on the 12z
HREF guidance.

Strong low-level moisture advection continues across northwest
TX/southern OK at 16z, and this trend is expected to continue and
expand north into southern KS with time. Strong diurnal heating amid
a rapidly moistening boundary layer and steep mid-level lapse rates
will yield strong/extreme MLCAPE this afternoon along and east of
the dryline.

Initial supercell development is anticipated late this afternoon
across northwest TX, where strong diurnal heating should continue to
erode CINH. Isolated intense supercell development is also expected
farther north along the dryline towards 00z across OK/southern KS,
where rapidly returning moisture into a well-heated boundary layer
coincident with a strengthening low-level jet should contribute to a
high-end/all hazards severe risk.  Additional isolated supercell
development is also anticipated near the warm front across northern
KS. The primary uncertainty remains storm coverage, with 12z
high-res guidance continuing to exhibit a range of solutions.  As
mid-level flow increases and a shortwave trough approaches, an
extremely favorable thermodynamic and kinematic environment is
expected to be in place across the Enhanced/Moderate Risk areas from
late afternoon into tonight. The risk for strong/intense tornadoes,
very large to giant hail, and significant severe winds remains
evident.

...Southeast...
Rapid diurnal heating of a moist low-level air mass is occurring
downstream of ongoing convection, and temperatures have warmed well
into the 80s as of 16z. Strong thunderstorms over southeast AL are
expected to continue moving southeast within a
moderately-sheared/northwest flow environment and be capable of
strong/possibly damaging gusts and severe hail.  A small
Slight/Level 2 Risk has been introduced with this outlook, where the
more favorable overlap of 35 kts of northwesterly effective shear
and moderate/strong instability will exist.

...Lower Great Lakes/upper Ohio Valley...
Widely scattered to scattered thunderstorms are expected near the
cold front this afternoon, and along a nearly parallel, prefrontal
trough/convergence zone. Storms should move eastward/southeast and
persist into early evening.

Aside from lift along those boundaries, activity will be supported
by diurnally weakened MLCINH, with surface dewpoints in the upper
50s to mid 60s F contributing to around 1500 J/kg MLCAPE.  Weak
low-level flow and nearly unidirectional low/middle-level wind
profiles will tend to limit shear, however sufficient cloud-bearing
layer shear should exist to support multicell storm structures.
Damaging gusts and isolated hail will be possible from the
best-organized convection.

$$