SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1151 PM CST Mon Mar 01 2021 Valid 021200Z - 031200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms appear unlikely on Tuesday. ...Discussion... As an upper low departs from New England into the Canadian Maritime Provinces, a less-amplified upper flow field will prevail across the U.S. on Tuesday. While an eastern Pacific upper low will begin to approach southern California overnight, the center will remain offshore through the period. The only feature of interest aloft -- with respect to the convective forecast -- will be a compact low initially over eastern Oklahoma, which will then move steadily east-southeastward to the lower Mississippi Valley by dark, and then continuing to the southern Appalachians vicinity by the end of the period. As this feature advances, a weak surface frontal wave is progged to evolve along the west-to-east baroclinic zone extending from the northern Gulf of Mexico to central Florida. The low should move just south of the mouth of the Mississippi River during the afternoon, and then to a position near or just south of Apalachicola FL after midnight as the surface front continues a slow northward drift across northern Florida. Eventually, a second wave -- which will eventually become the predominant one -- will begin developing along the retreating boundary, just off the Georgia Coast through latter stages of the period. Showers and thunderstorms are expected to spread across the central Gulf Coast States/Southeast, in a zone of warm advection atop a cool boundary layer. Instability should remain modest -- likely insufficient to support updrafts vigorous enough to produce any more than small hail. Even nearer the front/surface low overnight, i.e. across northern Florida, the boundary layer is expected to remain slightly stable -- likely precluding fully surface-based storms, and as such, any associated severe potential. Therefore, no risk areas will be added to the forecast, as probability remains below the MRGL risk threshold. ..Goss/Bentley.. 03/02/2021
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