Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Sun Jun 22 2025 20:03:55 ACUS01 KWNS 222002 SWODY1 SPC AC 222000 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0300 PM CDT Sun Jun 22 2025 Valid 222000Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE MIDWEST TO PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS.... ....SUMMARY... Isolated to scattered thunderstorms are expected today across the northern Plains and Upper Mississippi Valley, some of which could produce large hail, damaging wind gusts and tornadoes. Storms associated with severe gusts and hail may also develop across parts of the southern and central Plains, and Northeast. ....20z Update Central/Northern Plains... Current surface and satellite observations show strong heating occurring from far eastern WY, into the NE panhandle within a post-frontal upslope flow regime. As ascent from the primary trough across the northern Rockies moves overhead, storm initiation appears likely this afternoon. Weak destabilization, with moderate deep-layer shear suggests a few supercells are likely with hail and damaging winds the primary risk. A brief tornado is also possible with the stronger surface-based supercells given strong low-level veering. The MRGL and SLGT boundaries have been adjusted westward to better align with expected storm initiation along the terrain and stalled front. See MCD#1403 for additional short-term info. To the north across eastern SD/ND and MN, the severe risk continues largely as expected. Strong heating ahead of a surface low and warm front will support scattered storm development this afternoon and evening. Deep-layer shear will support supercells and clusters capable of all severe hazards. Storms will continue eastward this evening and overnight across northern MN with damaging gusts and hail likely. ....Northeast... In the wake of an earlier MCS, strong heating remains evident along a remnant outflow boundary from eastern PA into southwestern NY state. However, mid-level height rises and subsidence are evident in visible/WV imagery and will continue to suppress convective development over much of the region. An isolated storm or two remains possible along the boundary through late this afternoon, but more widespread convective coverage is unlikely. Should storms form, a strong/severe wind gusts will be possible, in addition to sporadic hail, given seasonably large buoyancy and steep mid-level lapse rates. With decreased confidence in storm development/coverage, have opted to remove the SLGT risk and continue with 5% wind/hail probabilities. ...Lyons.. 06/22/2025 ..PREV DISCUSSION... /ISSUED 1136 AM CDT Sun Jun 22 2025/ ....Northern/Central Plains into the Upper Midwest... A warm front extends northeast from a surface low over northern SD across northern MN and east across the northern Great Lakes. This warm front should lift north through the day, while a cold front extends southwest of the surface low into northeast CO. Thunderstorms over eastern ND/northwest MN have produced near severe gusts as they continue to move northeast towards the international border. Redevelopment of thunderstorms is anticipated towards late afternoon or early evening across eastern ND/western MN southward into eastern SD as a weak mid-level perturbation lifts northeast across the area, contributing large-scale ascent and weakening the capping inversion. These storms will move east/northeast within a strongly unstable air mass and include a mix of supercell and cluster modes with a risk for large to very large hail initially, and transition into an increasing wind threat with time. Tornado potential appears to be greatest over northern MN, where low-level SRH will be maximized. The potential for elevated, post-frontal thunderstorm development across the NE Panhandle will exist later this afternoon/evening, with storms moving east and posing a risk initially for severe hail. The severe wind potential will increase with eastward extent as storms congeal and tap greater surface instability farther east. ....Central/Southern High Plains... Low-level moisture advection and related airmass destabilization coupled with low-level convergence along the lee trough is expected to result in thunderstorm development from eastern CO/western KS through eastern NM and into far west TX. Vertical shear will be modest, likely resulting in predominantly outflow-dominant storm structures and the potential for damaging wind gusts. Some isolated hail is also possible with the strongest/more persistent updrafts. ....Northeast... Overall storm intensity along the western flank of outflow from the long-lived MCS remains sub severe, and have narrowed the Marginal and Slight Risk areas to along and immediately southwest of the convective line. Substantial diurnal heating of a very moist air mass, and 30-40 kts of effective shear, may support some severe potential as storms move generally southward along the eastern periphery of the mid-level ridge. Isolated to widely scattered strong/severe wind gusts will be possible, in addition to isolated hail reports given seasonably steep mid-level lapse rates. $$ = = = 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) .