Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
808 ACUS03 KWNS 260730 SWODY3 SPC AC 260729 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0229 AM CDT Wed Jun 26 2024 Valid 281200Z - 291200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF SOUTHEAST NE...NORTHEAST KS...CENTRAL/SOUTHERN IA...NORTHERN MO...WESTERN IL... ...SUMMARY... Severe thunderstorms may develop from parts of the central Plains into parts of the upper Midwest and upper Mississippi Valley on Friday. Large hail, damaging wind, and a couple tornadoes will be possible. ...Central/northern Plains into the upper Midwest/Great Lakes... A mid/upper-level trough will move eastward across the northern Great Plains into the upper Great Lakes region on Friday into Friday night. In conjunction with the shortwave, a surface low will move eastward across the Dakotas, with secondary low development possible across the central Plains. A warm front is forecast to move northward across the mid/upper MS Valley, while a cold front will move through the northern/central Plains into MN through the day and into the evening. Widespread convection will likely be ongoing at the start of the period, within a warm-advection regime. In the wake of the morning convection, moderate to locally strong destabilization will be possible in the vicinity of the cold front and a possible outflow boundary across parts of NE/IA into northeast KS/northwest MO, with somewhat more modest destabilization along the northward extension of the front into the eastern Dakotas and parts of MN/WI. The strongest mid/upper-level flow will move across the Dakotas into Minnesota, though modest westerlies farther south will support sufficient effective shear for some storm organization, both in the vicinity of the cold front and any outflow boundaries, and also within the post-frontal regime into parts of the central High Plains. Storm evolution during the afternoon/evening remains somewhat uncertain, but development of a few supercells and/or stronger clusters will be possible, both near the cold front somewhere from southeast NE and IA into northeast KS and northern MO, and also within a potentially favorable post-frontal regime across the central High Plains. Large hail and localized severe gusts will be possible initially, along with some tornado potential, especially if any supercells can develop within a belt of stronger low-level flow/shear currently forecast from eastern KS into northern MO, southern IA, and western IL. Farther north, the magnitude of destabilization remains rather uncertain into the eastern Dakotas and Minnesota, but strong deep-layer shear will support a conditional supercell threat, if sufficient pre-frontal buoyancy develops. A hail and severe-wind threat would accompany any persistent deep convection within this regime. A Slight Risk has been included where confidence is currently greatest regarding storm coverage within a favorable environment, from southeast NE/northeast KS into central/southern IA, northern MO, and western IL. Storm coverage is less certain across the eastern Dakotas and Minnesota, while the corridor of the most favorable post-frontal environment is also uncertain across the central High Plains. Greater probabilities may eventually be needed for those areas as well, depending on the resolution of these uncertainties. ..Dean.. 06/26/2024 $$