SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1120 PM CST Fri Nov 27 2020 Valid 281200Z - 291200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms appear unlikely across the contiguous United States today. ...Discussion... As a trough within the fast northern-stream westerlies moves quickly across the Northeast today, an upper low south of the main belt of polar flow will move gradually eastward out of New Mexico and across the southern Plains. As this low advances, weak surface cyclogenesis is expected to begin later in the day, along a remnant baroclinic zone extending from south Texas eastward across the northern Gulf of Mexico/Gulf Coast region. Elsewhere, high pressure will prevail across most of the remainder of the country. At the start of the period Saturday morning, two main areas of convection will be ongoing -- one over the Southeast near the remnant front, in conjunction with an eastward-moving disturbance, and the second over Texas and the western Gulf. With time, the southeastern U.S. convection is forecast to move eastward/offshore, though a few showers and storms may linger over northern Florida through the afternoon near the surface front. Meanwhile, the Texas convection is expected to increase in coverage and spread eastward with time, eventually spreading into Louisiana and vicinity into the overnight hours as quasi-geostrophic forcing for ascent persists ahead of the advancing upper low. However, inland instability will remain weak and elevated, and post-frontal convection acting to reinforce the cool/stable boundary layer. The only exception to this overall expectation could evolve along the immediate coastal counties of the middle Texas coast. Here, proximity to the evolving frontal low could allow modest surface-based instability near the coast, along with a somewhat favorable wind profile. However, this appears to be a very low-probability scenario at this time, with the low expected to remain just offshore. Therefore, no risk areas will be added at this time. ..Goss/Moore.. 11/28/2020
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