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