Severe Storm Outlook Narrative (AC)
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Issued by NWS
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180 ACUS01 KWNS 250100 SWODY1 SPC AC 250058 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Mon Jun 24 2024 Valid 250100Z - 251200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF THE UPPER MISSISSIPPI RIVER VALLEY... ...SUMMARY... Scattered severe thunderstorms are expected over parts of the Upper Midwest this evening and overnight. A corridor of potentially widespread destructive wind gusts could develop over parts of Minnesota into Wisconsin. ...01z Update Upper Midwest... Much of the previous forecast remains unchanged with only minor modifications. Several areas of scattered thunderstorms are ongoing over the northern Red River Valley and upper Midwest. Scattered supercells ahead of the occluded front over northern MN should continue eastward with a risk for damaging gusts and hail this evening before slowly weakening as they encounter decreasing buoyancy near Lake Superior. Farther south, complexities surrounding the isolated ongoing convection in southern WI and additional convective initiation of elevated storms near and north of the effective warm front remain substantial. Storms over southern WI appear likely to continue southeast on the fringes of the better ascent and buoyancy with a risk for damaging gusts and hail this evening. Observational data shows increasing low-level warm-air advection and upper-level ascent could support additional storm development this evening over portions of west-central MN with the potential for rapid upscale growth into a bowing MCS. Substantial spatial uncertainty is also evident in late afternoon CAM guidance, but most guidance now does indicate some form of relatively intense MCS forming along the front in the 02-04z time frame. With 5000-6000 J/kg MUCAPE and moderate effective shear in place, a swath of significant damaging winds remains possible over parts of eastern MN, and much of central/southern WI, though with substantial uncertainty. Will maintain level-3 Enhanced wind probabilities as is with minor adjustments to the level-2 Slight over lower MI where storms may persist through the end of the convective period. ...Carolinas... The cold front over the eastern US is slowly moving offshore this evening. Remaining storms have undergone a gradual decrease in coverage and intensity this evening with the cessation of diurnal heating and the weakening of broader-scale forcing for ascent. An isolated damaging gust could occur with the stronger storms centered near the NC/SC border, but the broader severe risk should continue to decrease below MRGL criteria after sunset. ..Lyons.. 06/25/2024 $$