SPC 0100Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0749 PM CDT Sat Jun 28 2025 Valid 290100Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER MIDWEST INTO THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered severe thunderstorms will spread across the upper Midwest and portions of the northern Plains this evening into the overnight hours. All severe hazards are possible. ...01z Update... Short-wave ridging has flattened across the northern Plains/upper Midwest as broader cyclonic flow now extends across the northern Rockies into the eastern Dakotas. This flow regime is notably diffluent across the upper Midwest, and scattered deep convection is maturing within this favorable environment from the upper Red River Valley into southwestern MN. While LLJ is not particularly strong at this time, latest model guidance suggests 1km flow could increase in excess of 35kt across southern MN by mid-late evening. Scattered supercells have evolved near the SD/MN border, and this activity could grow upscale as it propagates downstream along a weak boundary, aided by the aforementioned increase in LLJ and associated low-level warm advection. 00z sounding from ABR exhibited MLCAPE around 3000 J/kg with adequate deep-layer shear for sustaining organized updrafts. This supports the potential for all hazards with these storms into the late-evening hours. Upstream across the High Plains, water-vapor imagery suggests a weak disturbance is ejecting across southern MT, and this feature will shift into the western Dakotas by the end of the period. Isolated thunderstorms developed over the higher terrain southwest of Billings MT, and there is some concern for additional development ahead of the short wave later tonight as it encounters a bit more moisture/instability over southeast MT into the Black Hills region. Until then, a long-lived supercell is digging southeast across Jackson County SD, just south of Phillip. This storm has a history of producing very large hail and damaging winds. This activity may remain somewhat isolated as it propagates toward south central SD later this evening. ..Darrow.. 06/29/2025