SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0750 AM CDT Thu May 29 2025 Valid 291300Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHERN PLAINS AND SOUTHEAST... ...SUMMARY... Large to very large hail, severe winds, and a couple of tornadoes will be a concern with thunderstorms this afternoon and evening from the Texas-New Mexico border eastward into central Texas. Thunderstorms producing scattered damaging winds are possible later today across parts of the Southeast. An isolated severe threat may develop this afternoon across the Ozarks and Mid-South vicinity. ...Southern Plains... Strong daytime heating is expected today near/south of a cold front from parts of eastern NM into west-central TX. Generally 60s surface dewpoints and steep mid-level lapse rates will support MLCAPE up to 2500-3000 J/kg by mid/late afternoon, with 35-45 kt of deep-layer shear sufficient for organized convection, including supercells. Even though large-scale forcing associated with an upper trough over the Midwest and central Plains will remain modest with southward extent into the southern High Plains, robust thunderstorm development should initially occur by 19-22Z near the front across eastern NM into west-central TX, with increasing coverage and clustering possible this evening. Large to isolated very large hail (2-3+ inches in diameter) and severe gusts should be the main threats. There may also be some potential for a couple of tornadoes, especially in the vicinity of the surface boundary where low-level winds will be backed to east-southeasterly late this afternoon and early evening, modestly enhancing 0-1 km SRH. Farther east, most guidance depicts more isolated coverage of thunderstorms near the front from southern OK into north TX. However, moderate to strong instability and sufficient deep-layer shear will support a conditional risk of large hail and damaging wind with any sustained convection in this region. Isolated strong to severe thunderstorms will also be possible from the Raton Mesa vicinity southward across eastern NM, within a weakly unstable but favorably sheared environment. The strongest cores may pose a threat of isolated hail and severe gusts during the afternoon and early evening, before quickly weakening with eastward extent and the loss of daytime heating. ...Lower Mississippi Valley/Southeast... Thunderstorms are ongoing this morning along/near the coast across southern LA/MS/AL and the FL Panhandle. This activity is related to large-scale ascent and modest low-level warm/moist advection occurring ahead of a mid/upper-level trough moving eastward across the lower MS Valley. Some enhancement to deep-layer flow/shear associated with the trough could support occasional strong to locally severe thunderstorms this morning, but instability over land is generally expected to remain weak owing to poor lapse rates aloft and persistent cloudiness. Downstream of this morning convection and the mid/upper-level trough, diurnal heating of a moist airmass should foster the development of weak to moderate instability by this afternoon, with MLCAPE increasing to around 1500-2000 J/kg where stronger heating occurs. Strong to severe convection may either persist from the ongoing morning activity, or initiate within the weakly capped environment across parts of GA into SC. Low-level flow will likely remain rather weak, but some strengthening of westerly mid-level winds should support one or more loosely organized clusters capable of producing scattered damaging winds and perhaps isolated hail. The Slight Risk has been maintained for parts of GA/SC with this update, where confidence remains in stronger pre-convective heating/destabilization and steepening of low-level lapse rates. ...Ozarks into the Mid-South... Some low-level moistening is expected through the day from parts of northern AR/southern MO into the Mid-South, in association with a approaching mid/upper-level trough and developing weak surface cyclone. Relatively modest heating and weak lapse rates aloft may tend to limit buoyancy, but ascent attendant to the approaching shortwave trough may support scattered thunderstorm development along/ahead of a front from late afternoon into the evening. Increasingly favorable wind profiles and related deep-layer shear could support a few stronger cells despite the modest instability, with some potential for isolated damaging winds, hail, and perhaps a tornado. Greater severe probabilities may need to be considered for parts of this region, if observational trends support greater destabilization than currently forecast. ..Gleason/Leitman.. 05/29/2025