Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
033 ACUS03 KWNS 261940 SWODY3 SPC AC 261939 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0239 PM CDT Sat Apr 26 2025 Valid 281200Z - 291200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS IN CENTRAL AND EASTERN IA/SOUTHEAST MN/WESTERN WI... ...SUMMARY... An outbreak of severe weather remains likely across portions of the Upper Midwest, centered on Monday afternoon and evening. Very large hail, strong tornadoes, and damaging winds are expected. ...Synopsis... Multiple shortwave impulses embedded within a broader positive-tilt upper trough will eject into/across the North-Central States during the period. Primary surface cyclone, over central/eastern SD Monday morning, will remain nearly steady-state as it tracks east-northeast across the Upper Great Lakes. ...Upper Midwest... Elevated convection should be ongoing at 12Z Monday, centered on ND arcing southeast across the Upper MS Valley. Isolated severe hail may accompany this morning activity as it progresses eastward along the leading edge of a stout EML. Regenerative elevated storm development should persist northeast of the surface cyclone track across the Red River Valley through northern MN, likely limiting the northward advancement of the surface warm front during the day. Guidance differs markedly with the degree of northward destabilization into northern MN, lowering confidence in the degree of severe threat here. South of early-period storms/cloud coverage, pronounced destabilization will occur beneath the initially stout EML amid strong low-level moist advection. Cooling mid-level temperatures during the afternoon will be favorably timed with peak heating to support thunderstorms across southern MN into northern IA. Greater coverage is expected with northern extent which may yield more linear organization, compared to more discrete/isolated coverage trailing southward. A mix of all hazards is anticipated with an increasing severe threat into the early/mid evening as the low-level jet strengthens across the Upper MS Valley to Upper Great Lakes. The southern portion of this will be the more favored corridor for open warm sector discrete supercells capable of producing strong tornadoes. By late evening, linear clusters will likely overtake much of the discrete convection as the cold front advances rapidly east-southeast. Damaging wind gusts and embedded tornadoes will remain possible through the late evening and perhaps into the overnight hours. ...KS/MO to west TX... A strongly unstable/sheared warm sector will exist along/east of the dryline. Forcing for ascent should be much weaker than farther north with only weak mid-level height falls along the dryline. Most probable storm signals are after the nocturnal low-level jet increases during the evening in the southern Great Plains. This could support isolated supercells into Monday night. ..Grams.. 04/26/2025 $$