Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0350 AM CDT Mon Apr 14 2025 Valid 171200Z - 221200Z ...DISCUSSION... Active severe weather pattern expected late week into the weekend. ...D4/Thursday... A longwave trough should become clearly anchored over the West and consist of multiple embedded shortwave impulses. Peak surface cyclone amplitude is largely progged over western KS on Thursday afternoon, with a dryline arcing across eastern KS into the southern Great Plains. Another day of modifying moisture return northward from the western Gulf should yield at least moderate buoyancy ahead of the dryline. A strengthening low-level jet should support thunderstorm development across the Lower MO to Mid-MS Valleys on Thursday evening. Supercell wind profiles support potentially scattered severe storms. ...D5/Friday... A broad swath of strong mid-level southwesterlies appears likely to become established from the southern High Plains to the Great Lakes, downstream of a longwave trough from James Bay to the Lower CO Valley. While the deep cyclone over the KS vicinity will weaken, it should move towards the central Great Lakes. From along/ahead of its track to the trailing cold front arcing southwestward into west TX, extensive thunderstorm development is anticipated Friday afternoon/evening. Given the strong mid-level flow regime, scattered severe storms are possible across an elongated corridor. ...D6-7/Saturday-Sunday... Predictability for a 15 percent highlight remains too low during the weekend, but areas will probably be needed in later outlooks. Guidance has trended neutral to slightly weaker/more confined potential on Saturday. Overall signal persists of bimodal primary threat areas across the Lower Mid-Atlantic States and southern High/Great Plains. For the former, the degree of instability and position of a southeast-moving cold front on the periphery of stronger zonal mid-level flow remain key uncertainty factors. For the latter, timing of the pivot and eastward ejection of the compact Lower CO Valley shortwave impulse across the Southwest/southern Rockies remains crucial. Guidance has shown poor run-to-run continuity for Sunday, yielding low confidence on spatial details of the severe threat. Across both regimes and days, NSSL GEFS ML sub-15 percent probabilities appear quite reasonable.