Day 2 Convective Outlook  
NWS Storm Prediction Center Norman OK
1256 AM CST Wed Nov 25 2020

Valid 261200Z - 271200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
COASTAL/EAST TEXAS INTO LOUISIANA...

...SUMMARY...
Isolated large hail may occur with thunderstorms that develop across
parts of east Texas and Louisiana, mainly from Thursday night into
early Friday morning.

...Coastal/East Texas into Louisiana...
A positively tilted upper trough is forecast to move southeastward
over the western/central CONUS, with the southern portion of this
system closing off over the Southwest late Thursday. Ahead of this
feature, low-level moisture return should occur across parts of
coastal/east TX and the lower MS Valley through the period. 700-500
mb lapse rates around 7-7.5 C/km emanating from the higher terrain
of west TX and northern Mexico may overspread this region late
Thursday into early Friday morning. Latest guidance suggests MUCAPE
around 1000-1500 J/kg may develop along/north of a warm front, with
strengthening west-southwesterly mid/upper-level flow with height
that should support 40-50 kt of deep-layer shear. Confidence has
increased that mainly elevated storms may form by late Thursday
evening in a modestly strengthening low-level warm advection regime
over parts of east TX into LA, generally to the north of the warm
front. The forecast combination of sufficient instability, steep
mid-level lapse rates, and strong speed shear in the mid/upper
levels suggest that isolated large hail may occur with any elevated
supercells that can develop. The potential for surface-based storms
along the immediate upper TX Coast and southwestern LA remains too
uncertain to include any probabilities for strong/gusty winds at
this time.

...East Coast...
A de-amplifying shortwave trough should move across the Mid-Atlantic
and southern New England on Thursday. A weak surface low associated
with this feature is forecast to fill further through the day. An
eastward-moving cold front should extend from the Mid-Atlantic
southwestward along parts of the East Coast and into the Southeast.
The stronger mid-level flow attendant to the shortwave trough should
remain displaced to the north of greater low-level moisture across
the Carolinas and Southeast. Although enough weak instability may
develop across eastern portions of the Mid-Atlantic and southern New
England to support isolated thunderstorms Thursday afternoon, truly
surface-based convection still appears unlikely. From the Carolinas
into the Southeast, additional storms may occur through the day
along/ahead of the cold front. These areas will remain generally to
the south of stronger forcing for ascent tied to the previously
mentioned shortwave trough, with overall storm coverage expected to
remain fairly low.

..Gleason.. 11/25/2020

Day 3 Convective Outlook  
NWS Storm Prediction Center Norman OK
0228 AM CST Wed Nov 25 2020

Valid 271200Z - 281200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
CENTRAL/COASTAL TEXAS INTO LOUISIANA AND SOUTHWESTERN MISSISSIPPI...

...SUMMARY...
Isolated strong to severe thunderstorms may occur Friday across
parts of central/coastal Texas, Louisiana, and southwestern
Mississippi.

...Coastal Texas into Louisiana and Southwestern Mississippi...
Mainly elevated thunderstorms may be ongoing to the north of a warm
front at the beginning of the period across parts of east TX and LA.
This activity should be supported by modest low-level warm
advection, which is forecast to weaken through Friday morning.
Still, given the forecast combination of adequate
instability/mid-level lapse rates with strong deep-layer shear, this
convection may continue to pose an isolated hail threat mainly
through the morning hours across LA and perhaps southwestern MS
before diminishing.

As a closed upper low slowly pivots across the Southwest through the
period, a belt of enhanced west-southwesterly mid-level winds will
remain over much of central/coastal TX into parts of the lower MS
Valley. A east-west oriented surface boundary should be located over
these areas, with rich low-level moisture to its south. It appears
that this boundary will serve a focus for potentially robust
convection through the day, possibly beginning by early afternoon
across central TX as small-scale mid-level perturbations embedded in
the westerly flow aloft overspread this region. Weak to potentially
moderate instability along/near the front coupled with strong
deep-layer shear should support some organized convection. Isolated
large hail and strong to locally damaging wind gusts should be the
main threats as storms move slowly south-southeastward in tandem
with the surface front through Friday evening.

..Gleason.. 11/25/2020

Day 4-8 Convective Outlook  
NWS Storm Prediction Center Norman OK
0354 AM CST Wed Nov 25 2020

Valid 281200Z - 031200Z

...DISCUSSION...
Medium-range guidance has come into better agreement regarding the
eastward advance of an upper low over the southern Plains on Day
4/Saturday. Any severe potential Saturday appears to be confined
along/south of a surface boundary which should be located across
parts of coastal/south TX and perhaps southern LA. Some phasing of
this upper low with a northern-stream upper trough over the Midwest
seems probable on Day 5/Sunday. A northward advance of a partially
modified Gulf airmass may occur over parts of the Southeast Sunday,
with an associated isolated/marginal severe risk. Differences in the
evolution of a highly amplified upper trough/low over the eastern
states become apparent in medium-range guidance by Day 6/Monday.
Regardless, a continued isolated/marginal severe threat may exist
Monday across the warm sector of a deepening surface cyclone from
parts of FL and the Southeast along the East Coast and potentially
extending into the Mid-Atlantic. For Day 4/Saturday through Day
6/Monday, too much uncertainty currently exists regarding inland
destabilization to include 15% severe probabilities for any day.