Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1237 PM CDT Wed May 10 2017 Valid 111200Z - 121200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL APPALACHIANS VICINITY WEST-SOUTHWEST ACROSS THE OHIO VALLEY INTO PARTS OF THE SOUTHERN PLAINS AREA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK AREA... ...SUMMARY... Severe thunderstorms are possible on Thursday across eastern Oklahoma, northeast Texas, far northwest Louisiana, western and central Arkansas into southern Missouri. Large hail and strong wind gusts will be the main threat with these storms during the afternoon and evening. Additional strong to severe storms, mainly producing hail and some gusty winds, are possible across parts of the mid-Mississippi and lower Ohio Valleys to parts of the central Appalachians and eastern North Carolina. ...Synopsis... A closed low initially lying over the central/southern High Plains vicinity is progged to weaken/devolve into an open wave, as it progresses east and reaches the Ozarks late in the period. Elsewhere, a second/stronger low over the eastern Pacific is forecast to drift slowly east toward the Pacific Northwest Coast through the end of the period. At the surface, a baroclinic zone forecast to extend west-southwestward across the Ohio Valley area and into Missouri/Kansas/Oklahoma Thursday morning should advance slowly southward/southeastward with time, focusing a large region of convection from the Virginia/North Carolina area westward into parts of the southern Plains. ...Ohio Valley area westward to southeast KS/eastern OK/northeast TX... Showers and scattered thunderstorms are forecast to be ongoing at the start of the period, in the vicinity of the surface baroclinic zone. This convection should weaken through the day, allowing afternoon heating of the pre-frontal boundary layer to occur. By afternoon, heating in conjunction with a relatively moist low-level airmass will result in moderate destabilization, near and south of the front and ahead of a dryline progged to be shifting across eastern parts of the southern Plains. By mid-afternoon, ascent ahead of the advancing upper low/wave -- focused in the vicinity of the surface front/dryline -- should result in renewed/vigorous storm development. Initial convection will likely be cellular, though upscale growth into a more linear mode is expected in some areas -- particularly across the Ohio Valley area in the vicinity of the cold front. Dryline storms may remain more cellular for a longer period of time across the OK/TX/AR vicinity, where flow aloft more orthogonal to the boundary is expected. With mid-level flow averaging 40-60 kt from the west/west-southwest, shear will be supportive of organized/rotating updrafts. While areas of greater concentration of severe risk are somewhat difficult to narrow down at this point, pockets of large hail/damaging wind risk will likely evolve across a broad area, and thus will maintain a large 15%/slight risk across the region. Storms should diminish across the Ohio Valley and central Appalachians area after dark, but may linger/spread across Arkansas and east Texas and perhaps into Louisiana and the mid-Mississippi Valley area late in the period, along with some lingering hail/wind risk. ..Goss.. 05/10/2017Read more
from SPC Forecast Products http://ift.tt/ws9HZn
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