SPC Jan 12, 2024 0100 UTC Day 1 Convective Outlook

[NorthGeorgiaWX]

SPC 0100Z Day 1 Outlook

Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0659 PM CST Thu Jan 11 2024

Valid 120100Z - 121200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE ARK-LA-TEX...

...SUMMARY...
Severe thunderstorms, associated with tornadoes, damaging winds, and
large hail are possible tonight over the Ark-La-Tex, and in nearby
parts of southeastern Oklahoma, east Texas, Arkansas, and Louisiana.

...Ark-La-Tex...
The latest water vapor imagery shows an progressive upper-level
trough over the southern Rockies. An associated 90 to 120 knot
mid-level jet will translate quickly through the base of the trough
eastward into the southern Plains this evening. The exit region of
the mid-level jet will overspread the Ark-La-Tex by late evening.
Ahead of this feature, moisture advection will take place across
northeast Texas, Louisiana and far southwest Arkansas, where surface
dewpoints will likely increase in the lower 60s F. In response to
increasing low-level moisture and steepening mid-level lapse rates,
a pocket of instability will develop across the Ark-La-Tex by late
evening. Thunderstorms are forecast initiate within this pocket of
instability during the mid to late evening, and persist into the
overnight period. These storms should develop a severe threat, with
the threat aided by a split structure within the mid-level jet.

Concerning the timing of initiation, scattered thunderstorms are
expected to initiate in eastern Oklahoma around 03Z or 04Z, with
additional storms and greater convective coverage, developing
further to the south by 06Z. Considering that both deep-layer shear
and large-scale ascent will be very strong, supercell development is
expected. RAP forecast soundings around 08Z in far southwest
Arkansas have MLCAPE near 1200 J/kg, 0-6 km shear around 85 knots,
and 700-500 mb lapse rate approaching 8.0 C/km. This environment
will support supercells with large hail. The more dominant and
intense supercells could produce hailstones greater than 2 inches in
diameter. In addition, 0-3 km storm-relative helicity is expected to
increase into the 300 to 350 m2/s2 range,, supporting a tornado
threat. A strong tornado will be possible. As a line of intense
storms develops and moves eastward across the Ark-La-Tex tonight, a
wind-damage threat is also expected to develop. A few of the
stronger wind gusts along the leading edge of the line could peak
above 70 knots. The severe threat is expected to persist through the
end of the period, as the line of storms approaches the Mississippi
River.

...East Texas/Louisiana...
The axis of the mid-level jet is forecast to move eastward across
central and east Texas tonight. To the south of the mid-level jet
axis, instability and large-scale ascent are forecast to decrease
with southward extent. For this reason, any severe threat that
develops should be more isolated. Even still, deep-layer shear will
remain very strong, which could support a severe threat tonight.
Large hail, wind damage and perhaps a tornado will be the primary
threats.

..Broyles.. 01/12/2024

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