SPC AC 280645
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1245 AM CST Sat Jan 28 2023
Valid 291200Z - 301200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF
THE UPPER TEXAS COAST/EAST TEXAS INTO THE CENTRAL GULF COAST
STATES...
...SUMMARY...
Isolated strong to severe thunderstorms appear possible Sunday
across parts of the upper Texas Coast/east Texas into the central
Gulf Coast states. Some hail may occur with thunderstorms in east
Texas. Otherwise, occasional damaging winds and a couple of
tornadoes should be the main threats.
...Upper Texas Coast/East Texas into the Central Gulf Coast
States...
Mainly elevated thunderstorms will probably be ongoing Sunday
morning from parts of the upper Texas Coast into the lower MS
Valley. This activity will largely be tied to modest warm advection
associated with a 25-35 kt southwesterly low-level jet, and it may
pose an isolated threat for marginally severe hail as MUCAPE
gradually increases through the morning. A lead impulse embedded
within broadly cyclonic mid-level flow is forecast to develop
northeastward from the MS Valley towards the East Coast through the
day. A southern-stream shortwave trough should advance from TX
across the lower MS Valley and Southeast through the period. In
response to these developments, a broad and somewhat unfocused area
of modestly enhanced southwesterly low-level winds will overspread
parts of the central Gulf Coast states by Sunday evening. A surface
cold front should advance slowly southeastward over central/east TX
through Sunday night.
Latest guidance suggests that mid to upper 60s surface dewpoints
will attempt to spread northward in tandem with a marine warm front
across parts of LA, coastal/southern MS/AL, and the FL Panhandle.
Even though instability will likely remain weak owing to poor
mid-level lapse rates and limited diurnal heating, around 500-750
J/kg of MLCAPE should be sufficient to support a threat for
surface-based thunderstorms. 40-50 kt of deep-layer shear will
easily support convective organization, and around 100-200 m2/s2 of
0-1 km SRH should also foster some low-level updraft rotation. The
morning convection associated with the low-level jet should spread
eastward across LA/MS/AL through the day. Much of this activity will
remain elevated to the north of the surface warm front. But, there
is a chance for surface-based thunderstorms to occur across parts of
southern LA into coastal/southern MS/AL and the FL Panhandle,
especially where surface dewpoints can reach into the upper 60s as
some guidance suggests. Occasional damaging winds and a couple of
tornadoes should be the main threats as convection moves eastward
Sunday afternoon through Sunday night.
Additional thunderstorms may develop Sunday afternoon along/near the
cold front in east TX. Somewhat steepened mid-level lapse rates
emanating from northern Mexico should overspread this region. With a
broad mid-level southwesterly jet persisting over much of TX into
the lower MS Valley, strong deep-layer shear combined with 500-1000
J/kg MLCAPE (locally stronger) should support an isolated threat for
severe hail with any discrete cells that can develop. Occasional
damaging winds may also occur as these thunderstorms move into the
upper TX Coast and southwestern LA through early Sunday evening.
Large-scale forcing aloft will be somewhat nebulous across this
region in the wake of the southern-stream shortwave trough and as
the low-level jet shifts eastward through the day. Still, isolated
thunderstorms appear possible as low-level convergence increases
along the cold front by late Sunday afternoon.
..Gleason.. 01/28/2023
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