SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0221 AM CDT Sat Apr 12 2025 Valid 141200Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS IN THE UPPER OH VALLEY AND CENTRAL APPALACHIANS... ...SUMMARY... Scattered severe thunderstorms are possible on Monday afternoon and evening across parts of the Upper Ohio Valley and central Appalachians. ...Synopsis... A shortwave trough will further amplify over the Upper Great Lakes eastward towards the Ottawa Valley through early Tuesday. In its wake, a separate shortwave impulse and attendant mid-level jetlet will dive southeast across the northern Great Plains towards the Lower OH Valley. This will yield a broadening upper trough from the north-central into the eastern CONUS. At the surface, the lead wave will foster a near 990-mb cyclone tracking from Lake Superior to the ON/QC border. A cold front will arc south across the Lower Great Lakes and then southwestward through the Mid-South by late Monday. ...OH Valley to the Mid-Atlantic States... A high shear-low CAPE setup is anticipated on Monday afternoon and evening, despite the presence of an expanding EML across the region. Poleward moisture quality beneath the EML should remain sub-optimal, but will be improved relative to prior days. The drier spectrum of guidance appears more reasonable with mid to perhaps upper 50s surface dew points advecting as far northeast as the Upper OH Valley, ahead of the surface cold front. Guidance is reasonably consistent that at least isolated thunderstorms should develop in early to mid-afternoon across the Central OH Valley vicinity as mid-level height falls overspread the confined but destabilizing warm/moist sector. With already strong 700-500 mb southwesterlies strengthening further, fast-moving/highly sheared convection is anticipated. Despite veered surface winds, low-level hodograph curvature should be moderately enlarged. This setup may yield a few supercells that consolidate into a cluster spreading east across the central Appalachians. A couple tornadoes and damaging winds appear to be the primary hazards. East of the higher terrain, remnant steep low-level lapse rates may support a threat for isolated damaging gusts given the strong wind fields, before convection becomes increasingly elevated Monday night. ..Grams.. 04/12/2025
