SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1230 PM CDT Sat Jun 28 2025 Valid 291200Z - 301200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE UPPER MIDWEST INTO THE LOWER MISSOURI VALLEY... ...SUMMARY... Scattered strong to severe storms are possible Sunday from the central Plains into the upper Great Lakes region, with some potential for the evolution of a large, organized severe storm cluster across parts of the mid into lower Missouri Valley and central Great Plains late Sunday through Sunday night. ...Synopsis... An amplifying midlevel trough will advance east-southeastward from the north-central Plains toward the Upper MS Valley through the period. Related large-scale ascent will overspread the Middle/Upper MS Valley, while a related cold front moves southeastward across the region. ...Upper Midwest... In the wake of several overnight storm clusters and related cloud debris, gradual clearing should support boundary-layer destabilization and the development of moderate-strong surface-based buoyancy. As the cold front intercepts this increasing buoyancy, around 30 kt of deep-layer shear should favor a few organized clusters capable of producing widely scattered damaging wind gusts during the afternoon. ...Central Plains to the Middle/Lower Missouri Valley... A separate area of thunderstorms is expected along the front in IA and the Lower MO Valley during the late afternoon into the overnight hours. Ahead of these evolving storms, lower/middle 70s dewpoints beneath steep midlevel lapse rates will contribute to strong-extreme surface-based buoyancy. Initial storms will be capable of producing isolated large hail and locally severe wind gusts. However, strengthening deep-layer shear accompanying the digging midlevel trough, coupled with an increasing low-level jet, will support the development of a southward-moving MCS into the overnight hours. The Slight risk was expanded southward to account for this scenario, and higher wind probabilities may eventually be needed as the scenario becomes more clear. Farther west, semi-discrete storms are expected over the central High Plains during the afternoon. Elongated/straight hodographs and moderate surface-based buoyancy should favor large hail with any supercell structures that can develop. ...Mid-Atlantic... Despite marginal deep-layer flow/shear, diurnal heating amid deep tropospheric moisture (around 2 inch PW) will favor wet microbursts and the potential for wind damage with the stronger thunderstorms. ..Weinman.. 06/28/2025