Subj : MESO: Mesoscale Discussion 1971
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Nov 26 2022 19:18:45

ACUS11 KWNS 261918
SWOMCD
SPC MCD 261918=20
LAZ000-262145-

Mesoscale Discussion 1971
NWS Storm Prediction Center Norman OK
0118 PM CST Sat Nov 26 2022

Areas affected...Portions of southeastern LA

Concerning...Severe potential...Watch possible=20

Valid 261918Z - 262145Z

Probability of Watch Issuance...40 percent

SUMMARY...The risk for a couple tornadoes and isolated damaging
winds may gradually increase this afternoon. Trends are being
monitored for possible watch issuance.

DISCUSSION...A broken band of thunderstorms extends from coastal
southern LA into the Gulf of Mexico early this afternoon. This
activity is being aided by strong low-level warm advection and
large-scale ascent preceding an upper trough/low over the southern
Plains. Recent surface/platform observations across southeastern LA
and the Gulf of Mexico ahead of the ongoing convection generally
indicate that dewpoints have increased into the upper 60s to low 70s
along/near a marine warm front. This rich low-level moisture,
coupled with filtered daytime heating, may allow for enough weak
instability to develop inland to support surface-based
thunderstorms.

However, there is a broad area of showery precipitation ahead of the
main band of convection. It remains unclear how much this will
hamper attempts at diurnal destabilization this afternoon. Assuming
weak boundary-layer instability can be realized over southeastern
LA, both low-level and deep-layer shear will be quite favorable for
organized updrafts, with 0-1 km SRH of 200-300+ m2/s2 and 50-60 kt
of effective bulk shear expected. Occasional low-level rotation has
been noted with cells offshore earlier today, before they weakened
as they approached the coast. The threat for a couple tornadoes and
isolated damaging winds may gradually spread across parts of coastal
southeastern LA this afternoon through early evening with any
low-topped supercell that can be sustained. Given the potential
thermodynamic concerns/limitations, possible watch issuance will
largely depend on observational trends over the next few hours.

...Gleason/Hart.. 11/26/2022

....Please see https://urldefense.com/v3/__http://www.spc.noaa.gov__;!!DZ3fj=
g!-TQ-067COcfutX978WvZ3am0N0yXTcxTrhG_QylcTdJ5W6psQDXb71H9S3Km9l-MDuafJmaWx=
_qi1BdFVdPpWsmm2Hs$  for graphic product...

ATTN...WFO...LIX...

LAT...LON   29149090 30078966 30248910 30048877 29378878 28868918
            28848947 28948959 29168950 29258971 29228988 29009023
            28939088 29149090=20


=3D =3D =3D
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