ACUS01 KWNS 171632
SWODY1
SPC AC 171630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1030 AM CST Sun Nov 17 2024

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are expected to develop across parts
of west/northwest Texas into southwest Oklahoma this evening and
continuing through daybreak on Monday, posing a risk for severe wind
gusts and a few tornadoes.

...Synopsis...
Water-vapor imagery this morning shows a potent mid-level low/trough
over northwest Mexico with a downstream ridge centered over the
eastern Gulf of Mexico.  A mid-level vorticity maximum near the
middle part of the Gulf of California will pivot east into Chihuahua
by mid evening while the larger-scale trough becomes negatively
tilted and moves northeastward into the southern High Plains.  In
the low levels, cyclogenesis over northern Mexico will gradually
evolve today before the surface low deepens tonight reaching the
northwest TX/western OK vicinity at the end of the period.
Seasonably moist air via southeasterly flow from the western Gulf
will advect into west TX before a Pacific front sweeps eastward
across the Chihuahuan Desert and portions of the southern High
Plains tonight.  An attendant warm frontal zone will advance
northward from north TX into OK late.

...Southern Great Plains...
The 12 UTC Fort Worth, TX observed sounding showed an adequately
moist/deep moist layer featuring a mean mixing ratio of 12.6 g/kg.
The richer low-level moisture, featuring dewpoints in the mid-upper
60s as of late morning, is currently near the I-35 corridor from the
Metroplex and areas south/southeast.  Moisture advection will
contribute to gradual destabilization through this evening across
parts of west TX northeastward into southwest OK despite
considerable cloud cover through the day.  As an intense 100-kt
500-mb speed max moves from Chihuahua into west TX overnight,
large-scale ascent will favor the development of scattered
thunderstorms initially developing near the Permian Basin vicinity
and becoming more widespread as very strong low-level warm advection
attendant to an intensifying LLJ develops tonight.  Model guidance
indicates 250-1000 J/kg MLCAPE across the destabilizing warm sector.
A forced band of storms will likely evolve tonight across west TX
and rapidly move northeast in the area southeast of the surface low
track.  As the squall line matures, the propensity for severe gusts
will probably increase despite relatively poor lapse given the
intense flow expected to develop.  It remains uncertain if cellular
development will occur either ahead of the line or be loosely
maintained in parts of the larger band of storms.  Nonetheless,
elongated and enlarged hodographs will favor a risk for scattered
severe gusts and possibly a tornado risk, especially as the squall
line encounters greater moisture from west-central TX northeastward
into southwest OK late.

..Smith/Weinman.. 11/17/2024

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