125
ACUS03 KWNS 111909
SWODY3
SPC AC 111908

Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0208 PM CDT Mon May 11 2026

Valid 131200Z - 141200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE OHIO VALLEY AND CENTRAL APPALACHIANS AS WELL AS ACROSS
PORTIONS OF WESTERN MONTANA...

...SUMMARY...
Isolated severe storms will be possible on Wednesday across the Ohio
Valley and central Appalachians as well as portions of western and
central Montana.

... Overview ...

An amplified, yet progressive, midlevel pattern will persist on
Wednesday, with a shortwave trough moving across the northern
Rockies, an amplified ridge across the central US, and an amplified
longwave trough across the East. Embedded within the eastern
longwave trough, a shortwave trough will quickly pivot through the
basal region of the longwave trough, taking on a negative tilt as it
approaches the Mid-Atlantic Coast by the end of the forecast period.


At the surface, a low across Lower Michigan will move east across
the Great Lakes into northern New York and weaken as a new low
develops farther south along the front across the Mid-Atlantic
Region. As the initial low moves east, a surface front will also
move east across the Ohio Valley and approach the Mid-Atlantic
region by the end of the forecast period. Farther west, ahead of the
midlevel shortwave trough moving across the northern Rockies, lee
troughing will develop across the High Plains, with low-level
moisture beginning to return northward into the Central Plains.


... Ohio Valley and the Central Appalachians ...

A dry airmass will be in place across the region at the start of the
forecast period in the wake of a cool, dry anticyclone from the day
before. As the anticyclone moves east off the Atlantic Coast, modest
moisture advection will develop during the late morning into early
afternoon. The 20260511/12Z guidance suite shows varying solutions
regarding the depth and quality of the moisture return, with surface
dewpoints ranging from the upper-40Fs in the drier solutions to
perhaps 60F in the more moist solutions.

The depth and quality of the low level moisture will have an impact
on the resulting degree of instability and thunderstorm
potential/coverage. That said, the degree of forcing along the
surface front should support at least a few thunderstorms despite
instability generally around 500-1000 J/kg or less. The overall
kinematic profiles would support strong, gusty winds with any
thunderstorm that can sustain itself.


... West-central Montana into Central Montana ...

A negatively tilted shortwave trough will move across the area
during the forecast period. Despite very dry low levels initially,
increasing midlevel moisture and steep lapse rates may support a few
hundred joules per kilogram of MUCAPE during the late afternoon and
evening. As strong deep-layer ascent overspreads this environment a
few high-based thunderstorms may develop before the low-levels
moisten. Strong midlevel flow and a dry sub-cloud layer will support
at least a marginal threat for damaging wind gusts. One potential
negative for damaging wind gusts will be widespread cloud cover
associated with the increasing midlevel moisture that inhibits
destabilization. However, even in this scenario, gradient winds will
still pose a threat for damaging winds with any forced convection.

..Marsh.. 05/11/2026

$$