Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Tue Oct 21 2025 Valid 241200Z - 291200Z ...DISCUSSION... ...D4/Friday-D5/Saturday Southern Plains/ArkLaTex... The shortwave trough over the southern Plains and associated surface low/Pacific front will gradually move eastward Friday supporting scattered thunderstorms over parts of TX/OK. Overnight convection and continued low-level warm air advection is likely to impact the environment to some degree. This suggests very low predictability for any organized severe threat. Still, broad ascent, moderate deep-layer shear, and the potential for destabilization suggests at least some severe risk may develop from central OK southward toward the Red River and central TX vicinity Friday. Low-end severe potential will likely shift eastward into the ArkLaTex and lower MS Valley D5/Saturday as the upper low moves farther eastward. Most guidance shows the upper trough beginning to weaken with the surface features also becoming more ill defined with time. While the general environment likely will remain supportive of thunderstorms and isolated severe potential, details are sparse. ...Eastern Plains and Mid MS Valley D6/Sunday-D7 Monday... Higher severe potential may develop towards the end of the extended forecast period as a Pacific trough and amplified westerly flow develop over the western US D6/Sunday and move into the Plains and Midwest D7/Monday. Substantial variability exists between multiple ensemble and deterministic models regarding the evolution of the trough and resulting surface pattern. More amplified and less progressive solutions, along with some ML guidance, show the potential for a deep surface low and strong cold front to develop and sweep eastward. Should this occur, robust moisture return for fall is likely to develop along with strong low and mid-level wind fields across much of the central US. A favorable synoptic regime could support widespread severe storm development with sufficient instability/shear overlap for all hazards from the eastern Plains into the MS Valley and Midwest. This scenario remains highly uncertain with large variance noted between both ensemble and deterministic solutions regarding the structure and timing of the upper trough. Given the degree of spatial and temporal variance, predictability remains too low to justify probabilities in the extended forecast. However, 15% or higher severe probabilities could be needed in future outlook cycles should guidance trend towards a more unified/higher-end solution.
