SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0253 PM CDT Sun Apr 13 2025 Valid 132000Z - 141200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms will be possible from the Upper Mississippi Valley to the Great Lakes, and from the central Rockies to the lower Missouri Valley through tonight. Severe thunderstorms are not expected. ...20z Update... The prior forecast remains valid with only minimal changes to the western edge of the Thunder area. Isolated thunderstorms ongoing over parts of the Upper Midwest/Great Lakes should spread eastward through tonight. Additional elevated thunderstorms will remain possible across the OH Valley and Midwest as the low-level jet increases overnight. Given limited moisture, instability is forecast to remain too weak to support a severe threat. See the previous discussion for more info. ..Lyons.. 04/13/2025 .PREV DISCUSSION... /ISSUED 1100 AM CDT Sun Apr 13 2025/ ...Synopsis and Discussion... A mid-level shortwave trough will move eastward from the northern High Plains to the Upper Midwest by late tonight, as a surface low develops northeastward from eastern NE/KS to the upper Great Lakes. Limited low-level moisture return will continue through the period within the warm sector of this cyclone. But, sufficient ascent/saturation will likely remain confined to near the IA/MN border this afternoon, where elevated thunderstorms are ongoing. Some small hail may occur with this activity. This elevated convection is expected to spread eastward over WI and parts of Lower MI through the late evening. Farther west, isolated thunderstorms will be possible this afternoon into early evening along a southward-moving cold front across CO, and overnight into MO where moistening and weak ascent atop the front (near/above 700 mb) could support elevated convection by 09-12z. Across all these areas, instability is forecast to remain too weak to support organized severe thunderstorms.