Day 1 Severe Weather Outlook

Valid 102000Z – 111200Z


Severe thunderstorm winds, isolated hail and a tornado or two remain
possible late this afternoon and evening, mainly from parts of east
Texas and northern Louisiana into central Mississippi.

…20Z Outlook Update…
A convectively generated outflow boundary across central Mississippi
into northeastern Louisiana, and the segment of a quasi-stationary
surface front from northeastern Louisiana to a weak frontal wave
near Lufkin TX, may remain the primary focus for thunderstorm
development into at least early evening. Most of this convection
likely will be rooted within a zone of enhanced warm advection,
above stable near surface air to the cool side of the boundaries, as
an increasingly sheared mid-level perturbation (currently over
northern Texas) accelerates toward the lower Ohio/Tennessee
Valleys). However, weak to moderate boundary-layer destabilization
is ongoing to the south of the boundaries, and this instability may
provide support for continued deepening and intensification of
convection now spreading northward from the upper Texas and
Louisiana coastal plain. Given sustained boundary-layer based
thunderstorms, the environment is becoming at least conditionally
supportive of organized severe storm development in a narrow
corridor, roughly from near Lufkin TX across north central Louisiana
into the Jackson MS vicinity.

In the wake of the mid-level wave, a continued southward advancement
of the surface cold front into the Texas coastal plain appears
probable late this afternoon through tonight. However, models
suggest little change to the lower/mid tropospheric frontal
position, which is likely to remain the primary focus for any
renewed convective development with warmer mid-levels inhibitive to
the south. As the more moist and potentially unstable near surface
air becomes increasingly displaced from this zone, potential for
severe hail across south central Texas may begin to diminish by late
this evening.

..Kerr.. 02/10/2020

.PREV DISCUSSION… /ISSUED 1029 AM CST Mon Feb 10 2020/

…TX to LA/MS today…
A slow-moving front from TX to the lower MS Valley will provide the
primary focus for strong-severe thunderstorm development today.
Moist, moderately unstable (MUCAPE around 1500 J/kg) profiles are
present this morning from south TX to LA, where midlevel lapse rates
greater than 7.5 C/km overlie boundary-layer dewpoints of 67-70 F.
Vertical shear in this same corridor is sufficient for supercells,
with the stronger low-level shear and more favorable environment for
surface-based storms from east TX to west central MS.

Overall, the pattern will not change much through tonight. An
initial shortwave trough is ejecting east-northeastward over the
middle Rio Grande Valley toward central TX, and this ejecting speed
max will help maintain a weak surface wave on the front in the
vicinity of northwest LA. Training convection is expected along
the surface front from LA into MS today, where ongoing convection
will help reinforce the boundary. The stronger embedded
storms/supercells will pose a threat for damaging winds/large hail,
and perhaps a tornado or two. Farther west toward central TX, the
convection will be largely elevated on the immediate cool side of
the front, where the strongest storms could produce isolated large

…Southwest NM and vicinity this afternoon/evening…
Modest low-level moistening and surface heating is expected in the
vicinity of southwest NM, to the east of the midlevel low
approaching northern Baja. Lapse rates and vertical shear will
become sufficient for organized/strong storms, though the degree of
buoyancy is still in question. Will continue to monitor this area
for low hail/wind probabilities later this afternoon, assuming
evidence of sufficient destabilization.


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