12AM Day 2 Convective Outlook for Friday, August 29. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE SABINE RIVER VALLEY AND THE SOUTHERN INTO CENTRAL HIGH PLAINS
SUMMARY
Isolated strong to severe storms are possible across southeast Texas into southwest Louisiana, and over parts of the central/southern High Plains tomorrow (Friday).
Synopsis
An upper trough will meander over New England while upper ridging prevails across the western and central U.S. tomorrow (Friday). Surface high pressure will dominate the MS/OH Valley regions while a lee surface trough encourages moisture return across the western Gulf Coastal region into the southern and central High Plains. Multiple weak mid-level perturbations will traverse the upper ridge, serving as foci for thunderstorm development during the afternoon. Given a combination of at least marginal overlapping shear and instability over the High Plains to the Sabine River Valley, a couple of thunderstorms may approach severe limits.
Sabine River Valley
Multicellular convection, perhaps in the form of an MCS, will be ongoing at the start of the period, and likely weakening through the morning hours. This convection will leave behind an outflow boundary that will serve as the impetus for renewed convective development as the boundary layer warms during the afternoon. Surface temperatures will warm into the upper 80s F amid low 70s F dewpoints, yielding over 2000 J/kg MLCAPE. Deep-layer shear will not be particularly strong, with modest veering profiles contributing to 25 kts of effective bulk shear. Multicells will redevelop off of the outflow boundary, and will pose a risk for a couple of severe gusts by afternoon peak heating.
Central and Southern High Plains
A mid-level impulse will traverse the central Rockies by afternoon peak heating, aiding in the development of scattered thunderstorms, which will move off of the higher terrain over eastern CO/northeast NM. These storms will mature in an environment characterized by modest mid-level lapse rates and deep-layer shear, especially as they approach the CO/NE/KS border by afternoon peak heating. MLCAPE may exceed 2000 J/kg amid elongated hodographs and 35 kts of effective bulk shear. Both multicells and occasional supercells will be the primary storm modes, accompanied by threats for isolated severe wind and hail.