Valid 141630Z – 151200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF TX…
Isolated severe thunderstorms are possible across parts of Texas
from late afternoon into early Sunday.
…Northeast TX vicinity…
Along a southeast-sagging cold front, some models indicate
sufficient convergence for late afternoon to early evening
thunderstorm development. Morning satellite imagery indicates
thinning of upper-level cloud coverage in this region which should
yield moderate surface heating amid mid to upper 60s dew points.
Upper-level support will be lacking with near-neutral height change
as a shortwave trough ejects from the Lower MO Valley east across
the Midwest, lending to uncertainty over the degree of storm
development on the front. Should storms form, around 50-kt effective
shear would support updraft rotation, but predominately T-shaped
(looping back on itself between 850-700 mb) hodographs suggest
supercell structures may remain transient. Overall scenario appears
sufficient to warrant a Marginal risk.
…Edwards Plateau/South-central TX…
Thunderstorms may develop over the higher terrain of northern
Coahuila during the early evening within an environment favorable
for supercells. Guidance differs substantially on the degree of
development, which yields low confidence in potential evolution
across the Rio Grande. Steep mid-level lapse rates around 8 C/km per
the 12Z Del Rio sounding should be maintained and will likely yield
a rapid increase in MLCIN after sunset. It remains plausible that
any supercells over northern Coahuila could spread east of the Rio
Grande this evening, but would probably do so in an overall decaying
state given the increasingly strong inhibition. Marginal risk
probabilities will be maintained for severe hail and wind.
Strengthening low-level warm/moist advection will occur as the
trailing portion of the surface front becomes quasi-stationary
across the Edwards Plateau/Big Bend regions. Majority of guidance
breaks out elevated convection overnight near the NM/TX border area
of the Permian Basin. Strong speed shear through the cloud-bearing
layer will favor the potential for elevated supercells capable of
severe hail during the early morning.