SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Thu Oct 23 2025 Valid 231630Z - 241200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE SOUTHERN PLAINS... ...SUMMARY... Isolated severe storms are expected this afternoon into the overnight hours across the southern Great Plains. ...Southern Plains... A well-defined shortwave trough continues to push eastward through the Four Corners and Southwest this morning. Expectation is for this trough to extend from western CO southwestward through northwest NM and eastern AZ by early tomorrow morning. Enhanced mid-level flow associated with this trough will expand eastward into the southern High Plains by early this evening, with continued expansion into more of the southern Plains expected overnight. Mass response and modest surface cyclogenesis ahead of this shortwave will result in strengthening low-level flow throughout the day, with 60s dewpoints likely reaching northwest TX and southwest OK by 21Z. Low-level moisture advection is anticipated into the southern High Plains as well, but will be offset by strong heating/deep boundary-layer mixing. Late-afternoon dewpoints across the Permian Basin/TX South Plains will likely be in the mid 50s. The resulting discontinuity in the moisture (and temperature) fields may result in low-level convergence, although this convergence should be relatively modest given the diffuse character of the boundary and generally modest cyclogenesis. Even so, this convergence could be enough for convective initiation, particularly given its persistence. The best location for initial convective initiation appears to be in the northwest TX/southwest OK vicinity where the best overlap between low-level convergence, low-level moisture, and steep mid-level lapse rates exists. How this initial development evolves in uncertain, but there is some potential for a few supercells. Large hail is possible with any supercells early, with a trend towards more wind gusts as these storms become outflow dominant. Tornado risk will be limited by relatively weak low-level flow and higher storm bases, but a low-probability threat still exists given the increase vorticity near the boundary. Overall thunderstorm coverage is expected to increase significantly during the evening amid a combination of an increasing large-scale ascent and a strengthening low-level jet. This should largely favor elevated storm modes, with hail as the primary risk. That being said, increasing low-level moisture with eastern extent could result in trends towards more surface-based character and potentially a few stronger gusts. However, the more linear/clustered mode should keep the tornado risk low. ...NM and southern CO... Diurnally-driven storms will likely develop in closer proximity to the mid-level cold pocket over the southern Rockies. An isolated threat for marginally severe hail/wind is possible with this activity before subsiding during the evening. ..Mosier/Moore.. 10/23/2025
