Subj : DAY3SVR: Nws Storm Prediction Center Norman Ok To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sat Jun 21 2025 07:33:19 ACUS03 KWNS 210731 SWODY3 SPC AC 210730 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0230 AM CDT Sat Jun 21 2025 Valid 231200Z - 241200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE UPPER MIDWEST AND NORTHERN GREAT LAKES... ....SUMMARY... Strong to potentially severe storms may develop Monday from parts of the Great Lakes into the central Plains. ....Synopsis... Little change to the large-scale pattern is expected on Monday, with a persistent upper trough over the western CONUS, and an amplified upper ridge covering much of the East. A shortwave ejecting from the western trough is forecast to move quickly northeastward toward Hudson Bay by Monday evening. In the wake of this feature, guidance generally depicts only low-amplitude vorticity maxima moving around the periphery of the ridge from the central/southern Plains into the Great Lakes. At the surface, a front is forecast to be draped from the central Plains into the Great Lakes. The northeast portion of this front may continue to move eastward through the day, as a surface low moves across Ontario. To the southwest, the front may stall or begin to move northward as a warm front, as a weak surface wave persists over the central High Plains. ....Upper Midwest/Great Lakes... Potential for extensive convection on D2/Sunday creates some uncertainty regarding frontal position on Monday. Locally strong storms may be ongoing Monday morning, with a general increase in storm coverage expected during the afternoon where strong heating is realized in the vicinity of the front. Stronger deep-layer flow will again be displaced to the cool side of the front, but 30-40 kt of midlevel flow overlapping moderate to strong buoyancy will support some potential for organized storms. Mostly unidirectional southwesterly flow could support one or more forward-propagating clusters, with a threat of damaging wind and isolated hail. ....Central Plains vicinity... Deep-layer flow/shear will be somewhat weaker across parts of the central Plains, compared to areas farther northeast. However, strong heating will result in development of moderate to locally strong instability. Scattered storm development is expected within a weakly capped environment, and a few modestly organized cells/clusters could evolve with time, posing a threat for strong to severe gusts and isolated hail. Some westward moisture transport will be possible into parts of the central High Plains and Front Range, within a post-frontal regime. Isolated storms may develop within this regime, though generally modest midlevel lapse rates may tend to limit robust destabilization. ....Northern New England... Strong to extreme instability will again reside across parts of the Northeast and New England Monday afternoon, along the northern periphery of the upper ridge. However, the influence of the upper ridge is still expected to limit storm potential through the day. This region will continue to be monitored for the possibility that storms developing across Quebec may affect parts of northern New England, though this scenario is too uncertain for severe probabilities at this time. ...Dean.. 06/21/2025 $$ = = = 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) .