SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1123 AM CST Tue Jan 05 2021 Valid 061200Z - 071200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF EAST TEXAS AND INTO FAR SOUTHWESTERN LOUISIANA... ...SUMMARY... Scattered thunderstorms are possible Wednesday afternoon and night from eastern Texas into Louisiana. A few stronger storms are possible over southeast Texas during the afternoon. ...Synopsis... While one upper trough continues to depart from the Northeast Wednesday, and a second moves into/across the Pacific Northwest, the main feature aloft with respect to any possible severe weather will be a sharp trough emerging into the Plains. As vorticity within the southern portion of this trough -- initially crossing the southern high Plains -- advances, a closed low may evolve overnight, and shift across the Arklatex area by the end of the period. At the surface, weak cyclogenesis is expected over east Texas during the day, as the aforementioned upper system evolves. By late afternoon/early evening, a weak low should reside near the Sabine River Valley, while a trailing front sweeps eastward out of east Texas into western Louisiana and the western Gulf. By the end of the period, the low should reach southeastern Louisiana. ...East Texas/far southwestern Louisiana... As the upper trough advances/evolves, and a weak low develops over east Texas, some low-level theta-e advection and weak surface heating will allow modest destabilization to occur, with mixed-layer CAPE of a few hundred J/kg expected in the small inland warm sector during the afternoon. Elevated showers and thunderstorms are expected to develop during the morning over the northeastern Texas/Arklatex vicinity in a zone of pre-frontal warm advection, followed by more substantial convective development near -- and just behind -- an evolving cold front that will move across the area as the surface low develops. A few of the strongest storms may produce gusty winds, with a brief tornado also possible. The greatest risk would appear to exist over the southeastern Texas vicinity, where the southern fringe of more favorable low-level shear overlaps with the northern extent of the CAPE maximum -- particularly if any cellular, surface-based pre-frontal convection can evolve ahead of the low/front. Overnight, a slight/gradual stabilization of the low-level airmass is expected, which should allow any lingering severe potential to wane, though showers and storms will continue moving across Louisiana/Mississippi through the end of the period. ..Goss.. 01/05/2021
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