SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1129 AM CDT Wed Jun 04 2025 Valid 041630Z - 051200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN NEW MEXICO INTO THE TEXAS PANHANDLE... ...SUMMARY... Isolated severe thunderstorms are possible this afternoon into the evening across portions of the southern High Plains. Large hail and severe wind gusts are the primary concerns. Locally damaging winds may accompany convection that develops from the southern Great Lakes into eastern Texas. ...Southern Rockies into the Southern High Plains... Morning water-vapor imagery depicts a southern-stream midlevel shortwave trough moving eastward across AZ, which is accompanied by a 40-kt speed maximum in its base. Modest large-scale ascent preceding this feature will promote scattered thunderstorm development from the Southwest into the southern Rockies this afternoon (within the steepening low-level lapse rate plume), which will eventually spread eastward into the southern High Plains this evening. A modest uptick in storm intensity/organization is possible as storms move into east-central NM and eventually the TX Panhandle, given an elongated/straight hodograph (40-50 kt of effective shear) and steepening deep-layer lapse rates amid recycled boundary-layer moisture. A few organized clusters and supercell structures will be capable of producing large hail and locally severe wind gusts. Farther south over the TX Trans-Pecos, lingering inhibition and weaker large-scale ascent cast uncertainty on storm development/coverage, though isolated large hail and severe gusts will be possible with any storms that can evolve over the higher terrain this afternoon -- aided by moderate surface-based instability and around 50 kt of effective shear. ...Southern Great Lakes southward through the OH Valley and Ozarks into East Texas... A quasi-stationary cold front is draped from Lake Huron southwestward across the Ozarks into East TX. From roughly the Ozarks northeastward to eastern Lower MI, VWP data indicates a belt of 40-55-kt midlevel southwesterly flow, which will gradually shift northeastward into this evening. While 12Z regional soundings sampled poor midlevel lapse rates through this corridor, differential heating amid lower/middle 60s dewpoints ahead of the front and related convection will contribute to a weakly unstable air mass. This, combined with 40-50 kt of effective shear, will support loosely organized clusters (and perhaps transient/embedded supercell structures) capable of locally damaging wind gusts this afternoon. While a more-focused corridor of wind-damage potential is possible over southeast Lower MI into northeast IN, a lack of large-scale ascent, weak instability/lapse rates, and front-parallel deep-layer flow/shear limits confidence in this scenario -- precluding an upgrade to 15-percent wind probabilities at this time. Farther south into East TX, diurnal heating of fully modified Gulf moisture (middle 70s dewpoints) will result in stronger buoyancy, though deep-layer shear will be weaker here. As a result, locally severe gusts will be possible with predominantly outflow-dominant convection this afternoon. ..Weinman.. 06/04/2025