SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0736 AM CDT Mon May 26 2025 Valid 261300Z - 271200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF WEST-CENTRAL TEXAS... ...SUMMARY... Severe thunderstorms are likely today from parts of the southern Plains eastward into the lower Mississippi Valley. Very large hail should occur with initial development in parts of west-central Texas, with severe/damaging winds becoming a greater concern this afternoon/evening. ...Edwards Plateau to the ArkLaTex... A large complex of thunderstorms is ongoing this morning across parts of central/east TX into the ArkLaTex. Some of this activity may be elevated and occurring to the north of an outflow boundary from prior convection. Still, the southern portion of the line will have access to greater instability, and may continue to pose an isolated threat for severe/damaging winds this morning if it can remain surface based. In the wake of this activity, strong daytime heating is anticipated across west-central TX/the Edwards Plateau as a weak upper trough moves slowly eastward across the southern/central Plains through this evening. The front/composite outflow boundary from convection farther east should decelerate and stall over this region by the early afternoon, with a very moist low-level airmass in place to its south. Strong to locally extreme instability will likely develop by peak afternoon heating, with steep mid-level lapse rates contributing to this ample buoyancy. Current expectations are for multiple thunderstorms to initiate along/near the boundary across west-central TX by 18-21Z and quickly become severe. Although low-level winds are forecast to remain weak, mid/upper-level west-southwesterly flow gradually strengthening with height should support around 40-50 kt of effective bulk shear. This will easily foster intense supercells with the initial development this afternoon, and large to very large hail (some 2+ inches in diameter) appears likely. With time, clustering/upscale growth is anticipated as thunderstorms spread east-southeastward. An increasing threat for severe winds should develop as this mode transition occurs across central TX and vicinity. Given increased confidence in a focused corridor of very large hail and severe wind potential this afternoon/evening, have introduced an Enhanced Risk across parts of west-central TX with this update. ...Lower Mississippi Valley/Southeast... Extensive convective overturning occurred yesterday across much of the lower MS Valley/Southeast. Outflow related to this convection has settled well south into parts of northern/central LA and southern MS/AL/GA, with a remnant MCV noted in northeast GA. The potential for substantial destabilization to occur to the north of this boundary (as some guidance suggests) remains questionable, as thunderstorms are still ongoing this morning across much of northern LA into western MS. Still, the potential for at least weak instability to develop remains apparent across parts of the central Gulf Coast states. Isolated damaging winds should be the main threat with any clusters that can either spread eastward from the ArkLaTex or which develop separately this afternoon. ...Southern/Central High Plains... A modest low-level upslope flow regime will persist today across parts of the southern/central High Plains to the north of a surface cold front. While instability should remain limited, isolated to widely scattered convection should initially develop over the higher terrain, before subsequently spreading eastward across the adjacent High Plains through the afternoon/evening. Occasional severe hail and winds may occur with this activity, with some guidance suggesting a small cluster may eventually develop this evening across eastern NM into northwest TX. ..Gleason/Leitman.. 05/26/2025