SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1147 PM CST Thu Nov 26 2020 Valid 271200Z - 281200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM SOUTH TEXAS EAST-NORTHEASTWARD TO SOUTHERN MISSISSIPPI... ...SUMMARY... A couple of severe thunderstorms may affect areas from South Texas east-northeast to southern Mississippi Friday, with marginal hail and gusty winds the main threats with these storms. ...Synopsis... A northern-stream trough over central Canada and the adjacent north-central U.S. is forecast to move quickly eastward, while just south of the main belt of westerlies, a closed low will move more slowly eastward across Arizona and, later, New Mexico. Southeast of this low, a belt of moderately strong west-southwesterly flow will persist from northern Mexico across southeast Texas and into the Southeast. Within this flow field, several weak perturbations will progress across the southeastern quarter of the country and the adjacent Gulf of Mexico. At the surface, a weak baroclinic zone will linger across the Gulf Coast states through the day, though a southward surge will occur across Texas as high pressure strengthens over the central Plains. This baroclinic zone will loosely focus a persistent zone of showers and storms through the period. ...South Texas east-northeastward to southern Mississippi... Showers and thunderstorms -- likely ongoing across portions of southern and eastern Texas and into Louisiana at the start of the period -- are expected to evolve/increase in coverage through the day, generally in an elevated sense near and north of the surface baroclinic zone stretching across the area. Modest CAPE will support the convective activity, but will largely remain insufficient for particularly robust storms. Still, with rather strong mid-level west-southwesterlies (40 to 60 kt) atop the region, cloud-layer shear could support some organization/longevity of convection locally. Marginally severe hail is possible -- particularly with any updraft which could acquire transient rotation. Otherwise, locally gusty/perhaps damaging winds would be possible, mainly with a stronger storm or two in close proximity to the surface boundary. Though convection will likely continue, gradually spreading southeastward, through the second half of the period, severe threat should diminish in most areas after dark, as the front shifts into the Gulf, with the possible exception of the Texas portion of the risk area. ..Goss/Moore.. 11/27/2020
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