034
ACUS01 KWNS 230105
SWODY1
SPC AC 230103

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0803 PM CDT Sat Jun 22 2024

Valid 230100Z - 231200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MIDWEST AND WESTERN GREAT LAKES...

...SUMMARY...
Scattered severe thunderstorms are possible through this evening
across parts of the Midwest, mainly posing a risk of damaging winds
and a few tornadoes. Isolated damaging winds are possible over
southern New England.

...01z Update Midwest...

The primary severe risk through the next several hours across the
upper Midwest remains with the cluster of supercells ongoing over
southern WI. Strong low-level shear along the modified differential
heating zone will continue to support the potential for a few
tornadoes, especially with any supercells that are able to remain
relatively discrete. Otherwise, ongoing upscale growth is expected
to continue and one or more clusters/line segments appears likely to
emerge and track southeast across the remainder of southeastern WI
and northern IL. Damaging wind gusts and a couple of QLCS tornadoes
appear likely into this evening.

To the southwest of the WI cluster, additional storm development
over central/southern IA, northern MO, and western IL has thus far
been slow to organize along a weak cold front. Likely due to poor
mid-level lapse rates, convection has slowly increased in coverage
and intensity, and may continue to do so, as the front accelerates
and outflow consolidates. Given relatively strong mid-level shear
profiles (effective shear 40-45 kt) and sufficient buoyancy, one or
more clusters of strong to severe storms may evolve and continue
through this evening. Damaging gusts appear to be the most likely
threat, though some hail and a brief tornado will remain possible.

...Southern New England...
A cluster of severe storms has persisted across parts of upstate NY
and eastern PA this evening ahead of broad troughing over the Great
Lakes and southern Ontario. While buoyancy is expected to continue
decreasing with nocturnal stabilization, a few of these storms may
persist for a few more hours this evening. Increasing mid-level
shear ahead of the consolidating shortwave trough farther west will
support organized mutlicells or transient supercells capable of
occasional damaging gusts and isolated hail. Additional, likely
elevated, storms may develop overnight as low-level warm advection
increases over portions of northern New England.

...Dakotas...
Very isolated thunderstorms have developed within the post-frontal
regime in the wake of the consolidating Great Lakes trough across
the Dakotas. While buoyancy remains modest, relatively strong wind
profiles suggest a storm or two may remain strong enough to produce
isolated hail or damaging gusts into this evening. Have modified the
existing MRGL to capture the remaining environment more conducive
for hail and wind potential.

A summary of remaining changes follows; MRGL was removed across
portions of southwest FL and the Four Corners. Storms have decreased
in coverage and waning buoyancy suggests the risk for a sustained
severe threat is low. An occasional stronger storm may persist in
southern CO for another hour or two, but the severe risk should
continue to decrease near and after dark.

..Lyons.. 06/23/2024

$$