Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0245 AM CST Sat Nov 15 2025 Valid 181200Z - 231200Z ...DISCUSSION... Upper-level ridging over the Plains on Day 4/Tue will develop eastward over the eastern third of the CONUS through Day 5/Wed as a western upper trough slowly ejects over the Rockies and into the Plains around Day 6/Thu. Gulf moisture will return northward across the southern Plains and south-central states ahead of the ejecting upper trough. Isolated strong to severe storms may be possible on Wednesday across the southern Plains and Ozarks vicinity in a warm advection regime ahead of the upper trough. By Day 6/Thu, the upper trough should progress east across the Plains toward the Mississippi Valley, with a surface cold front sweeping eastward as this occurs, and some severe potential could accompany widespread thunderstorm activity ahead of the front. Confidence in coverage of severe storms Day 5-6/Wed-Thu is uncertain. Large spread (and poor run-to-run consistency) exists among forecast guidance. The GFS and ECMWF-AIFS are more similar compared to the dynamical ECMWF, indicating a slower ejecting trough and only modest surface cyclogenesis until late Thursday when the low ejects northeast toward the Mid-MS Valley/Great Lakes. Furthermore, while strong southwesterly flow will overspread northward returning Gulf moisture across the Plains and south-central states, forcing for ascent will be somewhat limited on Wednesday as the trough ejects more slowly. As the trough ejects on Thursday and a cold front becomes a focus for storm development, boundary-parallel deep-layer flow and a northeastward ejecting cyclone may favor a more anafrontal, training convection/heavy rainfall scenario. While severe potential certainly is in play for Days 5-6/Wed-Thu, these uncertainties preclude 15 percent probabilities at this time. Beyond Day 6/Thu, model disparity increases substantially and predictability is low.
