Day 1 Severe Weather Outlook

Valid 242000Z – 251200Z


Thunderstorms, some producing marginally severe hail and/or wind,
are expected across central Texas this afternoon and evening.

…Central Texas…
Despite the frontal passage, elevated instability and strong
deep-layer shear may support marginally severe hail across
north-central TX, and have expanded the 5% hail probabilities a bit
farther north.

To the south and ahead of the cold front, instability will continue
to increase with pockets of heating over south-central Texas. Cells
may eventually develop just ahead of the front once capping is
breached, with marginally severe hail possible. A more robust line
of storms is expected to develop along the front later this
afternoon and continue developing southeast through early evening.
Both marginal hail and wind will be possible, though there will be a
tendency for storms to become undercut by the surging cold air.

..Jewell.. 10/24/2019

.PREV DISCUSSION… /ISSUED 1130 AM CDT Thu Oct 24 2019/

…Central Texas this afternoon/evening and Gulf Coast overnight…
Little if any changes appear warranted for today’s severe risk
across the region. A positively tilted mid/upper-level trough over
New Mexico/Colorado will continue to dig southeastward toward
western portions of Oklahoma and Texas through tonight.

A cold front extends southwestward across the Ozarks and southeast
Oklahoma into north-central Texas (near the Metroplex) and
west-central Texas/Edwards Plateau vicinity. Scattered
showers/thunderstorms will remain common across north-central Texas
this afternoon, with an increase/expansion of thunderstorms likely
later this afternoon farther southwest across Texas along the
southeast-advancing cold front.

Ahead of the front, low-level moisture (60s F surface dewpoints)
will continue to increase, although cloud cover remains prevalent
across the pre-frontal warm sector at midday across the Hill Country
and broader portions of central/south-central Texas, particularly
along/west of I-35 corridor. That said, clouds should gradually
thin/dissipate this afternoon across central/south-central Texas.
60s F surface dewpoints and steep mid-level lapse rates, while
maximized in the post-frontal environment, should support upwards of
1000-1500 J/kg MLCAPE by peak heating.

Increasing near-surface-based thunderstorm development is expected
along the front by early-mid afternoon, and storms will spread
east-southeastward through late evening and overnight with the cold
front. The moderate buoyancy and effective bulk shear of 35-45 kt
will favor organized line segments and possibly some embedded
supercell structures within the band of frontal convection. These
storms may tend to be slightly undercut and reside just above the
shallow cool air mass at the surface, which will somewhat temper the
threat for large hail and damaging winds. The expected predominant
linear mode, undercutting front, and relatively weak low-level shear
in the warm sector (related to a lack of cyclogenesis) should limit
the tornado risk.

Overnight, convection across the northwest and north-central Gulf of
Mexico could approach the upper Texas and Louisiana coasts in a weak
warm advection regime. However, low-level shear will not be
particularly strong, and thus, overall severe potential currently
appears low.


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