SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1227 AM CDT Sat Oct 04 2025 Valid 041200Z - 051200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE CENTRAL ROCKIES INTO THE NORTHERN PLAINS... ...SUMMARY... Isolated severe wind gusts/hail may accompany the stronger thunderstorms across the central Rockies into the northern High Plains late this afternoon and evening. ...Central Rockies to northern Plains... Upper low over southern NV will begin to eject northeast over the next few hours, advancing into UT by 12z then open up as a progressive short-wave trough over WY/CO by early evening. This feature will move into the eastern Dakotas overnight as 500mb speed max intensifies and translates toward the upper Red River Valley by 05/12z. At the surface, synoptic front is expected to move very little, extending from southeast MB-eastern ND-southeast WY. While strong boundary-layer heating is forecast across the high Plains into southeast SD, instability should remain weak despite steep 0-3km lapse rates. Isolated thunderstorms should develop ahead of the short wave across southeast WY/NE Panhandle into western SD, but forecast soundings suggest hail will struggle to be more than marginally severe. Some gust potential exists where lapse rates are steep. More concentrated robust updrafts are expected along the cool side of the boundary from northern SD into eastern ND/northwest MN during the latter half of the period. Forecast soundings suggest the most buoyant parcels will be rooted near 850mb where MUCAPE could exceed 1500 J/kg. This post-frontal convection will be aided by a strengthening LLJ which should encourage some organization, especially given the approaching short wave. This activity will be focused mostly after sunset and hail could exceed 1 inch in the strongest elevated updrafts. ..Darrow/Lyons.. 10/04/2025
