Valid 131200Z – 141200Z
…THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN HIGH PLAINS…
Isolated severe thunderstorms are possible near the higher terrain
of southwest Texas and southeast New Mexico into the Texas South
Plains vicinity this afternoon and evening.
An upper-level trough will move eastward across the Four Corners
region today as southwest mid-level flow remains across the southern
High Plains. At the surface, a trough with surface dewpoints in the
50s F, will deepen across west Texas and southeast New Mexico.
Low-level convergence and instability will increase during the day
resulting in a corridor favorable for convective initiation.
Thunderstorms are first expected to develop in southeast New Mexico
on the northern end of the instability corridor in the early
afternoon. Large-scale ascent will increase across the southern High
Plains resulting in a gradual expansion of convective coverage along
the surface trough this afternoon. Thunderstorms are then forecast
to move east-northeastward across west Texas this evening and into
the Red River Valley during the overnight period.
Model forecasts differ on how much instability will develop along
the surface trough. While the NAM shows weaker instability, RAP
forecast soundings in west Texas are more aggressive in developing
moderate instability. MLCAPE is forecast to reach the 1500 to 2500
J/kg range which will support strong updrafts. RAP Forecast
soundings also show 0-6 km shear reaching the 60 to 70 kt m2/s2
range with 700 to 500 mb lapse rates of 7.0 to 7.5 C/km. This
environment would be favorable for supercells with large hail.
Directional shear in the low-levels with speed shear in the
mid-levels will contribute to enough shear for tornado development
as well. The greatest potential for an isolated tornado threat would
be in far southeast New Mexico and far West Texas where the
combination of instability and shear is forecast to be most
favorable. Thunderstorms will move east-northeastward across West
Texas this evening where instability should be considerably weaker.
As a result, wind damage and hail are expected to become the primary