Subj : DAY2 2/5 Risk MW to GP To : All From : Mike Powell Date : Thu Apr 17 2025 08:10:00 ACUS02 KWNS 170552 SWODY2 SPC AC 170551 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1251 AM CDT Thu Apr 17 2025 Valid 181200Z - 191200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM LOWER MICHIGAN TO THE SOUTHERN PLAINS... ....SUMMARY... Scattered severe thunderstorms are possible from the parts of the Great Lakes to the southern Great Plains, mainly during the late afternoon Friday into Friday night. Large hail and isolated severe gusts will be the main hazards with this activity. ....Synopsis... A positive-tilt large-scale upper trough will pivot south and east across portions of the north-central to western U.S. on Friday. A swath of 60-80 kt 500 mb flow will stretch from the southern Rockies to the Great Lakes ahead of the upper trough. At the surface, low pressure will develop northeast from the KS/MO/IA vicinity Friday morning, to southern Ontario/Quebec by early Saturday. As this occurs, a cold front will develop southeast across portions of the Mid-MS Valley/Great Lakes and southern Plains. A weak secondary surface low likely will develop across west TX, where a dryline will extend southward from the eastern Panhandle to the Big Bend region. Southerly low-level flow will transport modest boundary-layer moisture northward ahead of these surface features and beneath fast mid/upper southwesterly flow. This will support scattered severe storms late Friday afternoon into the overnight hours from portions of the southern Plains to the Great Lakes. ....Lower-MO/Mid-MS Valley to Great Lakes... Elevated thunderstorms north of a warm front will likely be ongoing during the morning into the afternoon across WI/northern MI. This activity may pose a risk for marginally severe hail. Meanwhile, a shortwave upper trough embedded within the northern branch of the larger-scale western U.S. upper trough will shift east across the northern Plains and Upper Midwest during the evening/overnight. This will facilitate the eastward progression of the surface front through the period, creating a focus for thunderstorm development. However, strong capping will limit development along the front, likely until closer to 00z, when stronger large-scale ascent overspreads the surface boundary and cooling aloft ensues. Thunderstorms will likely remain elevated atop the strong EML in the 850-700 mb layer, and will likely become undercut by the surface cold front given boundary-parallel flow through the cloud-bearing layer. Nevertheless, steep midlevel lapse rates and sufficient MUCAPE will support organized convection capable of producing large hail. With time, cells may become training clusters, posing some isolated risk for damaging gusts. ....Southern Plains Vicinity... As a surface low develops across west TX, a triple point will emerge near the eastern TX Panhandle/South Plains vicinity. A stout EML will preclude convective development for much of the day. Near the triple point and northeast along the advancing cold front, isolated to scattered thunderstorms should form in the 22-00z time frame. Supercell wind profiles with large MUCAPE, very steep lapse rates, and elongated hodographs suggests initial supercells will pose a risk for large to very large hail through early evening. Thereafter, boundary-parallel flow will result in clustering/training as convection also becomes undercut by the front. Damaging gusts also may occur with initial supercells given a well-mixed boundary layer/steep low-level lapse rates beneath the EML. Additionally, some strong gust potential could occur into the Ozarks vicinity as clustering ensues, but hail is expected to be the main concern. ...Leitman.. 04/17/2025 $$ --- SBBSecho 3.20-Linux * Origin: ILink: CCO - capitolcityonline.net (454:3/105) .