Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
890 ACUS02 KWNS 240537 SWODY2 SPC AC 240536 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1236 AM CDT Fri May 24 2024 Valid 251200Z - 261200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS SATURDAY EVENING THROUGH SATURDAY NIGHT ACROSS PARTS OF NORTHWESTERN OKLAHOMA...CENTRAL AND EASTERN KANSAS INTO WESTERN MISSOURI... ...SUMMARY... Severe thunderstorm development appears likely across parts of the central and southern Great Plains by Saturday evening. This probably will include a few supercells initially, before storms gradually evolve into an organizing cluster overnight, accompanied by a risk for large hail, a few tornadoes and severe wind gusts across parts of Kansas and Oklahoma into western Missouri. ...Synopsis... The most prominent mid-level short wave perturbations have mostly become confined to the northern mid-latitudes. This includes one forecast to dig southeast of the Canadian Maritimes and northern New England coast, another pivoting northeast and east of the Great Lakes region, and a third digging along/southeast of the western Canadian/U.S. border area. However, models indicate that subtropical ridging, centered over central Mexico and the southwestern Gulf of Mexico, will remain suppressed, with several lower-amplitude waves progressing around its periphery. This will include mid-level troughing likely to progress east of the south Atlantic Seaboard, and another perturbation accelerating out of the Southwest trailed by a similar strength perturbation accelerating east of the Great Basin. It appears that the latter two impulses will contribute to larger-scale troughing progressing across the lower Missouri Valley and central Great Plains by 12Z Sunday, accompanied by a deepening surface cyclone emerging from the lee of the Colorado Rockies. In the wake of a preceding cold front associated with the Great Lakes perturbation, which appears likely to stall southeast of the lower Great Lakes through the Ohio Valley, rapid low-level moisture return is forecast through the developing warm sector across the southern through much of central Great Plains by late Saturday evening. It appears this will reach much of the lower Missouri Valley by late Saturday night. Beneath a plume of warm and capping elevated mixed-layer air overspreading much of the central/southern Great Plains and lower Mississippi Valley, models suggest that the seasonably moist air will support large CAPE on the order of 2000-4000 J/kg. ...Great Plains... While the general synoptic evolution appears fairly certain, there is notable spread within/among the various model output concerning the details, and smaller-scale evolution. With low-level moisture return ongoing from the southeastern Great Plains during day, model output indicating later timing (probably after 26/00z) of the more appreciable increase in thunderstorm initiation seems likely to verify best. By early Saturday evening, it appears that the deeper boundary-layer moistening may become focused in a narrow corridor across northwestern Oklahoma into central Kansas, along/west of a strengthening southerly 850 mb jet (in excess of 50 kt by late evening). This may become the focus for the most intense potential supercell development, posing a risk for large, damaging hail and perhaps a strong tornado or two. This activity will tend to develop northeastward and eastward within the warm sector through mid to late evening, before forcing associated with lower/mid-tropospheric warm advection provides a potential focus for an upscale growing and organizing cluster near a warm front across central/eastern Kansas into western Missouri overnight. As this occurs, damaging surface gusts are expected to become the most prominent potential severe hazard. ...Lower Great Lakes/Allegheny Plateau into Ohio Valley... Deep-layer shear may be modest, but CAPE on the order of 1000-2000 J/kg ahead of the slowing front may become supportive of storms with potential to produce severe hail and wind during the day Saturday, before the onset of more substantive mid-level height rises in the wake of the mid-level short wave trough. ...Eastern Gulf States... It is possible that a convectively generated or enhanced perturbation, digging around the northeastern periphery of low-amplitude ridging, may contribute to vigorous renewed thunderstorm development by late Saturday afternoon and evening. In the presence of a seasonably moist boundary layer with sizable CAPE, stronger storms may be accompanied by a risk for potentially damaging wind gusts. ..Kerr.. 05/24/2024 $$