SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1258 AM CDT Sun Jun 11 2023 Valid 111200Z - 121200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS AND VICINITY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF EASTERN COLORADO...AND SOUTHEASTWARD TO NORTHWESTERN OKLAHOMA... ...SUMMARY... Severe thunderstorms capable of producing damaging winds and hail are expected across a broad area centered over the Tennessee Valley/Mid South. Risk for locally damaging gusts and hail will also exist over the central High Plains vicinity and across the Oklahoma Panhandle vicinity, and across portions of northern/northeastern Texas. A few storms capable of producing strong wind gusts will also be possible over the central and northern Nevada vicinity. ...Ohio/Lower Mississippi/Tennessee Valleys, and into the southern Appalachians and central Gulf Coast region... A short-wave trough -- embedded with seasonably strong cyclonic westerly flow on the southern fringe of a Great Lakes upper low -- is forecast to shift across the Mississippi Valley into the Mid South/Southeast today. As this occurs, a cold front -- aligned roughly along the Ohio River and Ozarks region at midday -- will shift southeastward into the Lower Mississippi and Tennessee Valleys through the afternoon and evening, and to the Appalachians and central Gulf Coast states by the end of the period. As daytime heating allows moderate warm-sector destabilization, thunderstorms are forecast to develop near and just ahead of the boundary by early afternoon, from the mid Ohio Valley west to the Ozarks. Storms should rapidly organize into bands, supported by relatively strong westerlies (30 to 50 kt) in the 850mb to 500mb layer. With relatively fast easterly storm motion expected damaging wind gusts should become increasingly widespread through the afternoon within multiple bowing bands. Hail will also be possible, with stronger storms. Storms will continue into the evening hours, possibly evolving into a larger-scale arc/band, and shifting eastward toward the Appalachians, and southeastward across Mississippi, Alabama, and northwestern Georgia. While damaging-wind potential will likely continue through the evening over the Southeast, storms should weaken farther north as they shift into more stable conditions anticipated over the central Appalachians. ...North Texas... Ridging aloft will prevail across the southern Plains today, which will the boundary layer to remain capped through most of the day, across most of the area. However, as late-afternoon temperatures heat well into the 90s, erosion of the cap locally as a result of boundary-layer mixing should allow isolated storms to initiate -- most likely over the North Texas area. With steep lapse rates aloft supporting strong high-based CAPE, large hail and damaging winds will be possible with any sustained storm, from late afternoon through mid evening before storms diminish diurnally. ...Parts of eastern Colorado southeastward to northwestern Oklahoma... Thunderstorm development is expected across the Front Range vicinity today, as afternoon heating contributes to moderate destabilization. With moderate mid-level westerly flow atop the area, a few stronger storms will likely evolve, and shift east-southeastward toward lower elevations into the evening. Along with potential for locally damaging winds, a couple of the strongest storms will be capable of producing large hail. ...Northern and central Nevada vicinity... As an upper low drifts northward toward/into the Great Basin, afternoon destabilization atop a deep mixed layer will result in development of high-based thunderstorms. While deep-layer shear will not be particularly strong, sub-cloud evaporative effects suggest potential for a few strong wind gusts, with westward-moving storms. Storms will diminish in intensity through the evening. ..Goss/Bentley.. 06/11/2023
