SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1126 PM CST Fri Dec 18 2020 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE MIDDLE AND UPPER TEXAS COAST... ...SUMMARY... Isolated strong to severe thunderstorms may occur today across parts of the middle/upper Texas Coast. ...TX Coast... Late-evening water-vapor imagery depicts a mid-level short-wave trough digging southeast across NM toward west TX. 500mb speed max associated with this feature is forecast to translate into the lower MS Valley by 18z, which will encourage a weak surface low to approach the middle TX Coast early, before shifting east as flow aloft veers quickly with the passing short wave. As a result, modified boundary-layer moisture will struggle to advance appreciably inland with the greatest penetration expected along the middle TX Coast around mid day. Prior to this, elevated buoyancy is expected to increase farther inland early in the period which should encourage convection rooted near 850mb. With time, surface-based thunderstorms should evolve along the advancing cold font and across the warm sector, which should remain predominantly offshore. Strengthening wind fields and adequate buoyancy suggest supercell structures are possible, though clustering and line segments should also be noted. Wind, some hail threat, and perhaps a tornado or two are the hazards possible with this activity. ..Darrow/Dean.. 12/19/2020
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