ACUS02 KWNS 180556
SWODY2
SPC AC 180554

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Mon May 18 2026

Valid 191200Z - 201200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE GREAT
LAKES TO THE SOUTHERN PLAINS...

...SUMMARY...
Widely scattered severe thunderstorms will be possible along a cold
front extending from the Great Lakes into the Ohio Valley and the
southern Plains on Tuesday. Damaging winds and large hail will be
the primary threats.

...Synopsis...
A mid-level trough will lift across the Great Lakes Region on
D2/Tuesday with a surface low moving east across southern Ontario
and Quebec. A trailing cold front will be located from the Great
Lakes south into the Ohio and mid Mississippi Valleys into the
Southern Plains. Convection will likely be ongoing across this
boundary at the beginning of the D2/Tuesday period.

...Great Lakes Vicinity to the Lower Ohio Valley...

Some convection may be ongoing across the cold front towards the
beginning of the D2 period, with additional development likely by
the afternoon along the eastward shifting cold front. Enhanced
mid-level flow aloft and weak to moderate instability will support
organized storms with potential for damaging winds and isolated
large hail. Additional afternoon thunderstorm development may extend
into the Northeast with potential for large hail and damaging wind.

...Mid Mississippi Valley to Southern Plains...

Convection will be ongoing at the start of the period from the mid
Mississippi Valley driven by the cold front and potential cold pool propagation. These boundaries will be the focus of
re-intensification of convection in the afternoon. Mid-level flow
aloft will be weaker across the region but sufficient shear for
organization should remain in place. A plume of more favorable
moderate to strong instability will be available across
central/northern Texas into southern Oklahoma. With afternoon
development, steep low to mid level lapse rates and moderate
instability will support potential for a few large hail reports.
With time, upscale growth will support a downstream damaging wind risk.

..Thornton.. 05/18/2026

$$

--- Scorpio BBS
* Origin: (618:250/6)

ACUS02 KWNS 300608
SWODY2
SPC AC 300607

Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
0107 AM CDT Tue Jun 30 2026

Valid 011200Z - 021200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
MID-MISSOURI VALLEY INTO CENTRAL WISCONSIN...

...SUMMARY...
Isolated to scattered strong to severe storms will again be possible
from the central Plains into the Upper Midwest as well the Northeast
on Wednesday. Severe wind gusts and large hail are the main concerns.

...Mid-Missouri Valley into central Wisconsin...
Models are in general agreement that a cluster/MCS will be ongoing
in the eastern South Dakota/southern Minnesota vicinity early
Wednesday morning. There is at least some potential for damaging
surface gusts with this activity. Further intensification could also
occur as the airmass destabilizes in parts of Wisconsin into the
afternoon. However the early day activity evolves, an outflow
boundary from this activity will serve as a focus for additional
afternoon thunderstorms. 70+ F dewpoints to the south of the
boundary will again promote strong to locally extreme buoyancy.
Moderate to strong mid-level winds on the southern flank of the
upper trough in Canada will allow for 40-55 kt of effective shear
near the surface boundary. Initial supercells will be capable of
large to isolated very large (around 2-2.5 in.) hail and perhaps a
tornado or two. Given the instability, strong downdrafts will likely
lead to upscale growth relatively quickly. The risk for
severe/damaging winds will become the primary hazard with time,
particularly if an MCS can develop. A Slight Risk has been added to
cover both potential scenarios.

...Northeast...
The forecast continues to be uncertain given the nebulous forcing
for ascent. Nonetheless, substantial buoyancy will be in place
across the region (3000-5000 J/kg MLCAPE). Effective shear of 35-40
kt will promote some storm organization. Model guidance shows
variable solutions from more isolated cellular activity to a cluster
moving southeastward out of Canada. Given the low confidence in
placing more organized activity, a Marginal Risk will be maintained
for now. Damaging winds and isolated large hail will be possible.

...Central High Plains...
Thunderstorm development is expected within the lee trough during
the afternoon. A deeply-mixed boundary layer will promote potential
for severe winds especially if any clustering can occur. Shear will
be modest and severe coverage is expected to be isolated.

...Southeast...
Strong buoyancy will be in place during the afternoon given rich
moisture (70+ F dewpoints). Shear will be quite weak with some minor enhancement in the lower Mississippi Valley. Models do show some
potential for clustering, but the location is quite variable. Lack
of even subtle features to focus convection keeps confidence in a
more organized damaging wind threat low.

..Wendt.. 06/30/2026

$$

--- Scorpio BBS
* Origin: (618:250/10)