Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
614 ACUS48 KWNS 300900 SWOD48 SPC AC 300859 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0359 AM CDT Thu May 30 2024 Valid 021200Z - 071200Z ...DISCUSSION... Medium-range models continue to indicate that flow across the eastern mid-latitude Pacific into North America may undergo substantive amplification during the middle to latter portion of next week. This is forecast to include building larger-scale ridging across much of the U.S. and Canadian Pacific coast through the Canadian/northern U.S. Rockies. Within an initially zonal regime preceding this evolution, guidance continues to suggest that modest surface cyclogenesis may accompany the eastward progression of a low-amplitude short wave trough, from the lee of the northern Rockies through the middle Missouri and northern Great Plains Red River Valley vicinity Sunday through Sunday night. Moderately large CAPE may develop beneath a plume of elevated mixed-layer air overspreading much of the Great Plains, from the developing cyclone southward. Strongest forcing for ascent and shear may focus the most substantive convective development from near the surface low/dryline across central South Dakota by late Sunday afternoon northeastward through central and southern Minnesota by late Sunday afternoon and evening. This may include a few supercells initially, before convection consolidates and grows upscale into an organizing cluster. It currently appears that sustained thunderstorm development may be much more isolated southward along the dryline through the remainder of the Great Plains. A considerably stronger short wave trough may dig downstream of the amplifying ridge by the early to middle portion of next week. This may be accompanied by strong surface cyclogenesis, and perhaps the evolution of a broad deep mid-level low centered over the Upper Midwest/Great Lakes region by late next week. This might be accompanied by a risk for strong to severe storms spreading from portions of the northern and central Great Plains as far east as portions of the Mid Atlantic and Northeast by late next week. However, due to still large model spread, which increases by early next week, severe probabilities are being maintained at less than 15 percent, but this could change in later outlooks for this period. ..Kerr.. 05/30/2024