Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Apr 27 2025 06:06:23 ACUS01 KWNS 270606 SWODY1 SPC AC 270604 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0104 AM CDT Sun Apr 27 2025 Valid 271200Z - 281200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR MUCH OF THE GREAT PLAINS... ....SUMMARY... Isolated to scattered severe thunderstorms are possible on Sunday evening into early morning Monday across parts of the Great Plains. Large hail, severe gusts, and a few tornadoes are all possible. ....Synopsis... A deep mid/upper-level trough will move eastward across the western CONUS today. A strong jet will move through the base of the trough and begin to impinge on the central/southern Great Plains by evening. The primary surface low will deepen through the day over the central High Plains and move northeast across NE/SD late tonight. A secondary surface low is expected to develop near/west of the Black Hills during the afternoon. A lee trough/dryline will extend southward into the southern High Plains. Relatively rich low-level moisture will initially be confined to the southern Plains this morning, but will stream quickly northward later today and tonight in advance of the surface lows and dryline. ....Northern Great Plains... Large-scale ascent is expected to increase by evening across the northern Great Plains vicinity, in association with the approaching mid/upper-level trough and jet that will overspread the region. Richer low-level moisture will remain mostly south of this region through much of the day, but steep midlevel lapse rates, moderate buoyancy, and increasing deep-layer shear will support development of a few supercells by evening with a threat of hail and damaging winds. The longevity of any surface-based storms is uncertain and could be limited, but some tornado threat could evolve with any supercells that can persist into the evening, as low-level moisture and shear continue to increase. Some clustering and upscale growth will be possible later tonight, with a threat for hail and damaging wind potentially spreading eastward across the Dakotas into MN before the end of the period. ....Central/southern High Plains... Conditionally, the warm-sector environment across the central and southern High Plains will become quite favorable for organized convection, with strong instability developing by late afternoon in conjunction with strengthening low-level and deep-layer shear. However, despite diminishing MLCINH from afternoon into early evening near the dryline, there is only an inconsistent and relatively limited signal for initiation. One area of potential development will be from west-central NE into northwest KS, in the vicinity of the primary surface low. Guidance also has a somewhat stronger signal for development into parts of the southern High Plains, where strong heating/mixing may result in more favorable low-level convergence on the dryline. There is a relative minimum in signal for storm development from west-central/southwest KS toward the OK Panhandle, but any supercell that develops within this region would be within an increasingly volatile environment during the evening, and pose an all-hazards severe threat. Given the very favorable environment and at least some potential for isolated supercell development by early evening in the vicinity of the dryline, the Slight Risk has been expanded southward for the conditional all-hazards threat. It remains possible that portions of the Slight Risk may see little or no storm development. ...Dean/Halbert.. 04/27/2025 $$ = = = To unsubscribe from WX-STORM and you already have a login, go to https://lists.illinois.edu and use the "Unsubscribe" link. Otherwise email Chris Novy at cnovy@cox.net and ask to be removed from WX-STORM. --- SBBSecho 3.20-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .