Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0315 AM CDT Wed Apr 23 2025 Valid 261200Z - 011200Z ...DISCUSSION... ...Days 5-7/Sun-Tue -- Great Plains to the Midwest... Forecast guidance is in good agreement that a deepening upper trough over the western states will eject eastward across the Plains and Midwest early next week. Beginning Day 5/Sun, the upper trough will extend from the central Rockies to the Southwest, with a belt of strong southeasterly flow emerging over the central/southern High Plains Sunday night. Surface lee low development is forecast over the northern/central Plains Sunday afternoon, with the low moving into SD/NE by Monday morning. Southerly low-level flow will transport ample moisture northward across the Plains and Mid-MO Valley on Sunday, with a sharpening dryline extending southward from western NE into western TX. Some severe potential could develop along the dryline and near the surface low/triple point. However, forecast soundings maintain strong capping and any convective development could be rather sparse. For now, this will preclude severe probabilities for Day 5/Sun. On Day 6/Mon, the upper trough will continue eastward, moving into the Plains by Tuesday morning. Ahead of the trough, a belt of strong southwesterly flow aloft will extend from OK into the Upper Midwest. A deepening surface low over SD will shift east/northeast through the period, with a trailing cold front shifting east/southeast across the Plains. Rich boundary layer moisture within a moderate to strongly unstable airmass and favorable shear parameter space will support an all-hazards severe weather episode across a fairly broad area from OK to MN/WI Monday afternoon into Monday night. Severe potential is likely to continue into Day 7/Tue, though some differences within medium range guidance with the evolution of the upper trough and key surface features does result in a bit more uncertainty compared to Monday, especially on the eastward extent of severe potential. Nevertheless, strong forcing atop a broad warm sector ahead of an eastward advancing cold front will continue to support severe potential from northeast Texas into Lower MI.