Valid 291300Z – 301200Z
…THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS EASTERN OK AND
Isolated severe storms are possible across parts of eastern Oklahoma
and northeast Texas during the early morning Saturday.
..Eastern OK and northeast TX…
No change to prior categorical forecast, although adjustments were
made to the spatial extent of tornado and wind probabilities.
Overall scenario remains similar to prior forecasts with potential
for surface-based convective development expected to be delayed
until the end of the period (09-12Z). Low-level moisture, emanating
from the western Gulf, will increase beneath an elevated
mixed-layer. Surface dew points should reach the mid 60s across
southeast OK overnight, yielding a corridor of thin MLCAPE of 500
J/kg up to 1500 J/kg in central TX. As an eastward-progressing cold
front impinges on the northern extent of this buoyancy plume,
forcing for ascent should effectively minimize MLCIN in the pre-dawn
hours tomorrow morning. The bulk of guidance suggests gradual
convective development will occur in this time frame. While 0-6 km
shear will be strong, mostly unidirectional southwest flow should be
oriented nearly parallel to the front. In addition, near-neutral 0-1
km lapse rates and progged veer-back signatures in the hodograph
between 850-700 mb will probably curtail sustenance of more robust
low-level updraft rotation. As such, have maintained a level 1
(Marginal) severe risk.
A prior QLCS along a pronounced cold front appears to be weakening
and shrinking in areal extent east of the Phoenix metro area. With
its prior feed of low 50s surface dew points having been effectively
pinched off to its southwest in the past hour, increasingly scant
buoyancy with eastern extent should preclude reintensification.