LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1256 AM CDT Sun Apr 23 2023
Valid 231200Z - 241200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTH
TX...
...SUMMARY...
Storms capable of severe wind gusts, large hail, and possibly a
tornado or two are possible over south Texas today, mainly this
morning into early/mid afternoon. Isolated wind gusts in excess of
75 mph are possible.
...Synopsis...
A deep upper trough will remain in place over much of the
central/eastern CONUS today. An expansive surface ridge will cover
much of the CONUS east of the Rockies, in the wake of a cold front.
Rich low-level moisture will mainly be confined to south Florida,
and also across south TX prior to the cold frontal passage. An
organized severe-thunderstorm threat is expected to develop during
the first part of the day across south TX.
...South Texas...
Considerable uncertainty remains regarding the evolution of
convection across south TX today, but there is some potential for
organized MCS development later this morning, which could pose a
threat of potentially significant wind gusts (along with some hail
and tornado threat) before storms move offshore.
Most guidance (both CAMs and larger-scale guidance) suggest storm
coverage will increase between 09-12Z this morning across southern
parts of the Edwards Plateau, aided by a modest southeasterly
low-level jet impinging on the southward-moving cold front. Eventual
upscale growth into one or more southeastward-moving clusters is
expected later this morning. Moderate buoyancy and favorable
deep-layer shear will support embedded supercell structures capable
of hail. Low-level shear will also be sufficient to support a
tornado or two with any sustained surface-based convection. Some
guidance depicts the development of a well-organized bowing MCS,
which would move southeastward toward portions of deep south TX and
the lower TX coast. Should this occur, a more concentrated area of
severe/damaging gusts may develop, including the potential for
isolated significant gusts.
The Slight Risk has been maintained with this outlook, due to
uncertainty related to the potentially complex evolution of
convection later this morning, and the timing and most favored
corridor for MCS development. However, a 10% significant wind area
has been added to account for the potential of localized significant
gusts. If confidence increases in an organized bowing MCS moving
across south TX, greater unconditional wind probabilities may be
needed later today.
..Dean/Bentley.. 04/23/2023
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