SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Wed Oct 04 2023 Valid 041630Z - 051200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF NORTHWEST/NORTH TX AND SOUTHWEST/SOUTH-CENTRAL OK... ...SUMMARY... Scattered to numerous severe thunderstorms are expected through early morning across parts of the southern Great Plains. Destructive, very large hail and significant severe wind gusts will be the main threats, along with possibly a couple tornadoes. ...Southern Great Plains... Confidence continues to increase with potential for a significant severe weather episode across north/west TX and south OK this afternoon into tonight, yielding expansion of the cat 3 severe risk. The northern extent of a rather rich western Gulf air mass has spread across much of north TX and southwest to east OK, characterized by upper 60s to low 70s surface dew points. Moderate boundary-layer heating coupled with the rich moisture will yield a broad plume of 2000-3000 J/kg MLCAPE by late afternoon. Elevated thunderstorms may continue to shift east into northeast OK while renewed development across the TX Panhandle will probably intensify by early afternoon as it transitions to surface-based development along the southward-sagging composite cold front/large-scale outflow. Scattered thunderstorm development is also anticipated southward into the Trans-Pecos as low-level convergence/upslope increases near the dryline. A lack of surface cyclogenesis will result in relatively weak low-level mass response and correspondingly small low-level hodographs this afternoon in the warm sector. However, substantial speed shear above 700 mb will yield relatively straight and highly elongated mid to upper-level hodographs favoring splitting supercells with initial storm development. These initial supercells will be capable of producing very large to giant hail from 2-3.5 inches, mainly across west TX where steeper mid-level lapse rates and discrete supercell mode will persist longer. Farther north and east, consolidating outflow interactions and minimal convective inhibition will likely result in quicker upscale growth into clusters and bowing line segments by late afternoon/early evening as storm coverage becomes widespread. Still, given the favorable hodographs for strong mid-level rotation, longer-track embedded supercells will be possible, especially along the composite front/outflow across south OK initially, and over western north TX later. These may yield destructive wind-driven hail swaths with localized gusts reaching 75-85 mph. A large MCS is anticipated this evening, moving east-southeast over north/northeast TX with a decreasing severe wind risk overnight. ..Grams/Bentley.. 10/04/2023
