904
ACUS02 KWNS 041731
SWODY2
SPC AC 041730

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1230 PM CDT Sat May 04 2024

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE TEXAS
HILL COUNTRY INTO THE MIDDLE TEXAS COASTAL PLAIN...

...SUMMARY...
Strong to severe thunderstorms may occur Sunday across parts of the
southern Plains into the ArkLaTex and Mid-South, and separately over
portions of Ohio into western Pennsylvania. Highest severe
thunderstorm potential is expected from the Texas Hill Country into
the Middle Texas Coastal Plain.

...Synopsis...
A southern-stream shortwave trough, likely enhanced somewhat by
widespread thunderstorms Saturday night, is expected to begin the
period extended from central OK through southeast TX. This shortwave
is forecast to make steady northeastward progress throughout the
day, reaching the Lower OH Valley by late Sunday night/early Monday
morning. A separate north-stream shortwave trough will likely will
move across Ontario and western Quebec, with an attendant surface
low moving just ahead of this wave. An associated cold front will
extend southwestward from this low, and is expected to progress
eastward across the OH Valley throughout the day. Southern portion
of this front (i.e. from the Mid-South into central TX) will remain
largely stationary throughout the day, before then transitioning to
a warm front amid strengthening return flow overnight.

Farther west, a deep upper cyclone is forecast to progress eastward
across the Great Basin before devolving into more of an open wave as
it moves through the central Rockies and into the central High
Plains. Strong mid-level flow will accompany this system, spreading
eastward and reaching the southern/central High Plains by early
Monday morning.

...Southern Plains into the ArkLaTex and Mid-South...
Showers and thunderstorms will likely be ongoing from eastern OK
into central and southeast TX at the start of the period early
Sunday morning, although with varying convective modes.  A more
linear, modestly organized convective line may be ongoing across
southeast TX, remnant from Saturday night/early Sunday morning
activity across central TX. Gradually decreasing buoyancy should
lead to gradual weakening of this line as it moves into
west-central/southwest LA. Even so, given the potentially organized
character to the line, some damaging gust will still be possible.

A more multicellular mode is anticipated throughout the day from
eastern OK into the Arklatex and Mid-South, supported by persistent
forcing for ascent and modest buoyancy. A few stronger updrafts
capable of hail are possible, with some limited potential for a few
bowing segments capable of damaging gusts as well.

Farther west, an outflow boundary is expected to extend westward
from this decaying convective line, likely from the middle TX
Coastal Plain through the Hill Country into the Edwards Plateau.
This boundary will likely provide the focus for addition
thunderstorm activity during afternoon. Ample low-level moisture,
strong buoyancy, and moderate deep-layer shear support the potential
for supercells with any discrete development. Large hail is primary
hazard with initial development, but some trend towards upscale
growth is likely, with the resulting convective line tracking along
the outflow boundary. Mesoscale nature of this scenario does lead to
some uncertainty, particularly on the location of the outflow
boundary, but guidance is consistent enough to delineate higher
probabilities from the TX Hill Country into the Middle TX Coastal
Plain.

...Ohio into Western Pennsylvania...
As mentioned in the synopsis, a weak front is forecast to move
eastward across the OH Valley Sunday. Modest destabilization should
occur ahead of this front across OH and western PA, contributing to
the potential for isolated to scattered thunderstorms along and
ahead of this boundary. Deep-layer shear of 20-30 kt should support
marginal updraft organization, with occasionally strong to damaging
gusts as these storms spread east-southeastward across parts of OH
into western PA and vicinity Sunday afternoon and early evening.
This activity should gradually weaken through the evening across PA
as it encounters a less unstable airmass.

...Northern High Plains...
Despite limited low-level moisture and scant buoyancy, increasing
mid-level moisture and strengthening large-scale forcing for ascent
ahead of the Great Basin shortwave is forecast to support the
development of isolated thunderstorms late Sunday evening. Given the
high storm bases and strengthening mid/upper flow, a few strong
gusts are possible. Even so, the overall severe threat appears too
limited to include low severe probabilities with this outlook.

..Mosier.. 05/04/2024

$$