SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0759 AM CDT Thu May 08 2025 Valid 081300Z - 091200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE TENNESSEE VALLEY...SOUTHERN APPALACHIANS...SOUTHEAST AND THE RIO GRANDE VALLEY OF TEXAS... ...SUMMARY... Scattered thunderstorms with severe wind gusts and large hail are expected today over parts of the Tennessee Valley, and southern Appalachians, with hailstones greater than 2 inches in diameter possible. Severe wind gusts and large hail will also be possible in other parts of the Southeast, as well as West/South Texas including the Rio Grande Valley. ...Tennessee Valley/Southern Appalachians to Southeast... A positively-tilted mid-level trough, with an upper low centered over the Ozarks this morning, will move through the Ohio and mid Mississippi Valleys today, and toward the Appalachians tonight. Surface dewpoints to the south of an advancing cold front will range from the mid 50s to the mid 60s F. As surface temperatures warm during the day, moderate instability is expected to develop with minimal convective inhibition beneath relatively cool mid-level temperatures via the proximity of the upper cold pocket. Storms will steadily increase into the afternoon with some supercells and organizing clusters from western and central Kentucky into middle Tennessee, eastward into the southern Appalachians. These storms will develop south-southeastward into northern Alabama, northern Georgia and the western Carolinas by late afternoon. Large hail can be expected, with hail greater than 2 inches in diameter possible especially with the more discrete and intense supercells. Damaging wind gusts can also be expected regionally. Another relatively favorable area for severe storms may focus across southeast Georgia and nearby far southern South Carolina and/or far north Florida this afternoon through early evening. This will be coincident with somewhat stronger mid-level flow as compared to areas farther south across the northern/central Florida Peninsula, where isolated severe storms are still expected. Regarding northern Florida this morning, see Mesoscale Discussion 738. ...West/South Texas including Rio Grande Valley... A low-latitude shortwave trough will progress east-southeastward across far northern Mexico and along the Rio Grande Valley today and tonight. A corridor of moderate to strong instability will be in place across the Rio Grande Valley. As surface temperatures warm today, scattered thunderstorms are expected to develop in the higher terrain of northern Mexico, with convection spreading eastward into and across the Rio Grande Valley, potentially with multiple rounds/corridors of severe weather possible across South Texas. Regarding short-term severe potential across South Texas, see Mesoscale Discussion 739. Strong deep-layer shear will contribute to supercells capable of large to very large hail and damaging wind gusts, especially if storms cluster/organize across the Rio Grande Valley later this afternoon into evening. ..Guyer/Dean.. 05/08/2025