Subj : DAY1SVR: Day 1 Convective Outlook To : wx-storm@lists.illinois.edu From : COD Weather Processor Date : Tue Jul 22 2025 06:02:33 ACUS01 KWNS 220602 SWODY1 SPC AC 220600 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Tue Jul 22 2025 Valid 221200Z - 231200Z ....THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN PLAINS INTO NORTHERN MN... ....SUMMARY... Scattered severe thunderstorms are expected over parts of the northern Plains into the upper Mississippi Valley later today into tonight. ....Northern Plains into the Upper Great Lakes region... An active severe-weather day still appears possible across parts of the northern Plains into the upper MS Valley/Great Lakes, though considerable uncertainty remains regarding the evolution of storms through the day. One or more storm clusters and possibly a remnant MCS may be ongoing at the start of the period somewhere from eastern ND into northern MN, though guidance varies regarding the details. Any organized cluster or MCS that is ongoing may pose a threat for at least localized damaging gusts into parts of northern MN through the morning, along with some hail potential with any semi-discrete cells. A surface low is forecast to move eastward across SD through the day, downstream of a positively tilted upper-level trough over the northern Rockies. An outflow-influenced surface boundary will extend northeast from the low into parts of the eastern Dakotas and northern MN, though its placement is somewhat uncertain by afternoon. Strong instability will develop by afternoon near and south of the boundary, and also within a region of moist east/northeasterly flow north and northwest of the surface low. The strongest mid/upper-level flow will be north of the boundary, but backed low-level flow near the boundary will result in favorable deep-layer shear for organized convection. There will be some potential for supercell development near the surface low and northeastward along the boundary during the afternoon and evening, though coverage is uncertain due to rather subtle large-scale forcing. Any sustained supercells within this environment could pose some tornado threat, in addition to potential for large to very large hail and localized severe gusts. Greater tornado probabilities may be needed if confidence increases in supercell development during the afternoon and evening. Farther west, widely scattered storm development is again expected across parts of MT and northern WY, initially within the post-frontal environment. Moderate instability and favorable deep-layer shear will support a mixture of cells and clusters with hail and severe-wind potential as they move east-northeastward. With time, upscale growth will be possible, either from convection moving out of the northern High Plains, or from storms developing farther east near the surface boundary. This could result in potential for a swath of damaging winds during the evening and overnight, though the favored corridor for this potential remains uncertain at this time. ....IA into southern MN/WI... An MCV generated by the extensive MCC over the central Plains Monday evening is forecast by most 00Z guidance to move northeastward toward IA and southern MN/WI through the period. The extent of flow enhancement and storm development associated with this feature is uncertain, but it is forecast to track across a moist and unstable environment during the afternoon and evening, and could aid in the development of a few strong storms. Locally damaging gusts will be possible, and a tornado cannot be ruled out if the MCV remains somewhat vigorous. ....Parts of the Southeast... A weak cold front will move across parts of the Carolinas and Georgia today into this evening. Very rich moisture (PWs above 2 inches) will support scattered to numerous thunderstorms along/ahead of the front, and in association with the sea breeze. Strong to locally damaging gusts will be possible, mainly during the afternoon and evening. ....Southern/central Rockies/High Plains... Relatively high-based thunderstorms are again expected this afternoon and evening across parts of the central/southern Rockies and adjacent High Plains. Localized strong to severe gusts may accompany these storms, though with relatively modest buoyancy and weak deep-layer shear, the threat appears too disorganized and nebulous for probabilities at this time. ...Dean/Wendt.. 07/22/2025 $$ = = = 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 3.28-Linux * Origin: capitolcityonline.net * Telnet/SSH:2022/HTTP (1:2320/105) .