967
ACUS01 KWNS 130602
SWODY1
SPC AC 130600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Mon May 13 2024

Valid 131200Z - 141200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
SOUTH-CENTRAL TX TO THE WESTERN GULF COAST REGION...

...SUMMARY...
Severe thunderstorms are expected today from central and east Texas
across parts of the Gulf Coast states. The potential may develop for
corridors of significant wind gusts, very large hail, and a few
tornadoes.

...Synopsis...
A mid-level trough will traverse the southeastern U.S. today, with
multiple embedded impulses poised to pivot around the trough an
support multiple rounds of thunderstorms this morning into later
tonight. Earlier rounds of convection will reinforce a surface
baroclinic boundary just north of the I-10 corridor, which may
either remain stationary or drift slowly north through the day.
Continued low-level warm-air and moisture advection ahead of the
mid-level trough will boost at least elevated buoyancy on both sides
of the baroclinic boundary, while cooler mid-level temperatures
overspreads the southern Plains into the Lower MS Valley. Stronger
mid-level flow accompanying the cooler temperatures aloft will
result in appreciable deep-layer shear coinciding the aforementioned
buoyancy, which will support multiple rounds of strong to severe
thunderstorms, spanning from parts of the southern Plains to the FL
peninsula through the forecast period.

...Portions of central into eastern TX...
Showers and thunderstorms should clear out of central TX through the
early to mid-morning hours, allowing for 8+ C/km mid-level lapse
rates to overspread a moist boundary layer. Though diurnal heating
may be limited by cloud cover to a degree, temperatures should rise
over 80 F, supporting 2000-4000 J/kg SBCAPE (perhaps locally higher
in spots) given the aforementioned dewpoints/lapse rates. A belt of
stronger mid-level flow will overspread the region, supporting
elongated, straight hodographs supporting splitting supercells as an
initial storm mode. Large hail will be the main threat with these
storms, with some of the largest stones potentially reaching 2-4
inches in diameter, especially of a more sustained supercell
structure can develop. With time though, storms should grow upscale
into an MCS later in the afternoon/evening as they interact more
favorably with the baroclinic boundary. By this point, severe gusts
become the primary threat, with a couple of QLCS tornadoes also
possible.

...Portions of the southern Plains into the Ozarks...
Showers and thunderstorms should linger across much of the southern
Plains into the Ozarks from the morning to at least mid-afternoon.
Weak surface low development is anticipated across MO/AR later in
the day, which will encourage modest low-level moisture advection
beneath gradually steepening mid-level lapse rates. SBCAPE should
rise into the 1000-1500 J/kg range later in the afternoon.
Deep-layer shear is not expected to be overly strong, though some
elongation of straight hodographs suggests that multicells or brief,
transient supercells may develop and produce isolated instances of
severe hail or wind.

...The Gulf Coast...
The potential for multiple rounds of thunderstorms introduces
complications to the forecast. Strong to potentially severe
thunderstorms, perhaps in the form of an MCS, may be ongoing at the
start of the period across portions of the Lower MS Valley. These
storms may be ongoing along or north of a baroclinic boundary, along
the eastern periphery of a buoyancy axis, characterized by poor
lapse rates but abundant low-level moisture. SBCAPE may be as high
as 1500 J/kg as the MCS moves through. Forecast hodographs depict
modest low-level curvature and mid-level elongation as the low-level
jet passes over the Gulf Coast. As the MCS traverses the baroclinic
boundary and ingests locally higher effective SRH, damaging gusts
and tornadoes may occur. However, the passage of this first MCS may
shunt the baroclinic boundary further south toward the Gulf Coast,
which will impact the evolution of subsequent thunderstorm clusters.
Should the boundary not be shunted offshore, the TX afternoon
thunderstorms, congealing into an MCS, may traverse the boundary and
pose a damaging gust/tornado threat along the Gulf Coast during the
evening/overnight hours.

...Parts of the Florida Peninsula...
At least one of the lead embedded mid-level impulses should traverse
the northern FL Peninsula, most likely by afternoon, when surface
temperatures will rising into the 80s F amid dewpoints around 70 F.
Though mid-level lapse rates will be relatively poor, the strong
surface heating of the moist airmass will boost SBCAPE into the
1000-2000 J/kg range amid 30-40 kts of effective bulk shear.
Multicells and transient supercells are expected to initiate during
the afternoon, especially along sea-breeze boundaries, with isolated
instances of hail damaging gusts possible, and a tornado cannot be
ruled out.

..Squitieri/Goss.. 05/13/2024

$$