Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
070 ACUS02 KWNS 230602 SWODY2 SPC AC 230600 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Sun Jun 23 2024 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF MN AND FAR NORTHEAST ND INTO NORTHWEST WI AND WESTERN UPPER MI... ...SUMMARY... Severe thunderstorms are possible on Monday across parts of the northern and central Great Plains into the upper Mississippi Valley and Great Lakes. Isolated severe storms are also possible across the coastal Carolinas. ...Northern Great Plains into the upper MS Valley and Great Lakes... A rather conditional Slight Risk has been maintained across parts of MN into northern WI and western upper MI, where confidence in storm development within a favorable environment is currently highest. A mid/upper-level shortwave trough and related surface low are forecast to move eastward across parts of SK/MB during the day on Monday. A weak secondary surface low may develop along a trailing cold front across the eastern Dakotas, while a warm front will move northeastward across MN through the day. The environment will become conditionally favorable for severe thunderstorms through the day, with increasing low-level moisture beneath a stout EML supporting strong buoyancy across the warm sector, in the presence of moderate deep-layer shear. Storm coverage and evolution remain uncertain across the region, due to EML-related capping concerns and generally modest large-scale ascent. There is some potential for early-day convection across ND to spread southeastward through the day with some severe threat. Isolated storm development will also be possible near the cold front from the far eastern Dakotas into west-central/northwest MN. Some increase in elevated convection will be possible Monday night across a larger portion of MN into northern WI, in response to an intensifying low-level jet. Any surface-based storms that develop within this regime could become supercells, with an attendant threat of very large hail, localized severe gusts, and possibly a tornado. There will also be some potential for upscale growth into a southeastward-moving MCS by Monday night, depending on the evolution of convection earlier in the day. A southeastward expansion of greater severe-wind probabilities may eventually be needed if confidence in the MCS scenario increases. ...Black Hills vicinity into parts of NE and western IA... The southern portion of the surface trough/weak cold front moving across the Dakotas is forecast to reach parts of NE by afternoon. Strong heating in the vicinity of the boundary will support isolated to widely scattered high-based thunderstorm development. With generally weak midlevel flow across the region, storms may quickly become outflow dominant, but steep tropospheric lapse rates will support at least isolated severe gusts. The strongest updrafts may also be capable of producing some hail. Farther west, high-based convection may also develop from eastern WY into the Black Hills vicinity, which may spread eastward into the early evening with a threat of isolated severe gusts. ...Coastal Carolinas... A cold front is forecast to move across the coastal Carolinas vicinity, with scattered thunderstorm development expected during the afternoon. Moderate to locally strong prefrontal buoyancy (with MLCAPE of near/above 2000 J/kg) and effective shear generally around 25-30 kt will support potential for a few stronger multicells and perhaps a marginal supercell or two, with an attendant threat of locally damaging winds and hail. ..Dean.. 06/23/2024 $$