SPC 1730Z Day 2 Outlook

Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1123 AM CST Tue Jan 05 2021

Valid 061200Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
EAST TEXAS AND INTO FAR SOUTHWESTERN LOUISIANA...

...SUMMARY...
Scattered thunderstorms are possible Wednesday afternoon and night
from eastern Texas into Louisiana. A few stronger storms are
possible over southeast Texas during the afternoon.

...Synopsis...
While one upper trough continues to depart from the Northeast
Wednesday, and a second moves into/across the Pacific Northwest, the
main feature aloft with respect to any possible severe weather will
be a sharp trough emerging into the Plains.  As vorticity within the
southern portion of this trough -- initially crossing the southern
high Plains -- advances, a closed low may evolve overnight, and
shift across the Arklatex area by the end of the period.

At the surface, weak cyclogenesis is expected over east Texas during
the day, as the aforementioned upper system evolves.  By late
afternoon/early evening, a weak low should reside near the Sabine
River Valley, while a trailing front sweeps eastward out of east
Texas into western Louisiana and the western Gulf.  By the end of
the period, the low should reach southeastern Louisiana.

...East Texas/far southwestern Louisiana...
As the upper trough advances/evolves, and a weak low develops over
east Texas, some low-level theta-e advection and weak surface
heating will allow modest destabilization to occur, with mixed-layer
CAPE of a few hundred J/kg expected in the small inland warm sector
during the afternoon.  Elevated showers and thunderstorms are
expected to develop during the morning over the northeastern
Texas/Arklatex vicinity in a zone of pre-frontal warm advection,
followed by more substantial convective development near -- and just
behind -- an evolving cold front that will move across the area as
the surface low develops.  A few of the strongest storms may produce
gusty winds, with a brief tornado also possible.  The greatest risk
would appear to exist over the southeastern Texas vicinity, where
the southern fringe of more favorable low-level shear overlaps with
the northern extent of the CAPE maximum -- particularly if any
cellular, surface-based pre-frontal convection can evolve ahead of
the low/front.

Overnight, a slight/gradual stabilization of the low-level airmass
is expected, which should allow any lingering severe potential to
wane, though showers and storms will continue moving across
Louisiana/Mississippi through the end of the period.

..Goss.. 01/05/2021

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