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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0732 AM CDT Sun May 15 2022

Valid 151300Z - 161200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THROUGH THIS
EVENING FROM SOUTHEAST KS AND NORTHEAST OK INTO NORTHERN AR AND
SOUTHERN MO...

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS
AFTERNOON/EVENING FOR THE INTERIOR PACIFIC NORTHWEST...

...SUMMARY...
Scattered to numerous severe storms with very large hail and swaths
of wind damage are expected from mid morning through this evening
from eastern Kansas and western/southern Missouri into Oklahoma and
Arkansas.  Other isolated severe storms will be possible later this
afternoon across the interior Pacific Northwest.

...Eastern KS/OK to MO/AR through late evening...
Elevated convection is ongoing this morning across northeast KS, in
advance of a midlevel shortwave trough moving east-southeastward
over western/central NE.  The convection will be maintained in a
zone of ascent preceding the midlevel trough, and will likely
intensify this morning while encountering increasing low-level
moisture/buoyancy across eastern KS and western MO.  Strengthening
deep-layer, west-northwesterly shear (effective bulk shear in excess
of 45 kt), midlevel lapse rates near 8 C/km, and MLCAPE increasing
to near 3000 J/kg by midday will favor clusters/embedded supercells
capable of producing very large hail up to 2.75 inches in diameter. 
Upscale growth into a larger cluster or two appears probable through
the afternoon across southwest MO, southeast KS, and northeast OK,
with an increasing threat for swaths of damaging winds of 60-75 mph.
 

A deep mixed layer and relatively weak convective inhibition suggest
that the storms could develop at least as far southwest as the I-35
corridor in central OK by this evening, where thermodynamic profiles
will favor damaging outflow winds.  The richer moisture/larger
buoyancy suggest the eastern extent of the stronger/sustained MCS
will likely be across AR, with more uncertainty with eastward extent
from the MS River.  Some form of the MCS(s) could make it as far as
the Mid South and the Red River Valley of OK/TX, though the severe
threat should be diminishing by this time (this evening/early
tonight).

...OH Valley into PA/western NY this afternoon...
A weak midlevel trough/vorticity lobe will move eastward from the
upper OH Valley across WV/PA/NY today.  A diffuse surface trough is
expected from central NY southward in the lee of the Appalachians. 
These features could help focus scattered thunderstorm development
by midday into this afternoon, and a few of the storms could produce
strong outflow winds and minor damage, along with marginally severe
hail in an environment characterized by weak vertical shear and
moderate buoyancy (MLCAPE of 1000-1500 J/kg).

It appears there will be a relative gap in any severe threat across
far western NY/PA and eastern OH, to the west of the weak shortwave
trough.  Additional convection will form farther west toward the
lower OH Valley into southeast Lower MI later this afternoon in
advance of the stronger shortwave trough (now over NE) and an
associated surface cold front.  The stronger vertical shear will
remain farther to the west during the day, with the larger buoyancy
farther southwest.  However, the strongest storms will be capable of
producing at least isolated wind damage and marginally severe hail,
and some low-end severe threat may persist into the OH Valley as the
convection spreads east into tonight.

...Interior Pacific Northwest/northern Rockies this afternoon...
A co*pact shortwave trough now off the OR coast will move
east-northeastward over OR/WA and the ID Panhandle by this evening. 
Boundary-layer dewpoints in the upper 40s to lower 50s, daytime
heating in cloud breaks, and increasing ascent with the approaching
shortwave trough/front will support thunderstorm development this
afternoon across northeast OR.  Though buoyancy will not be
particularly large (MLCAPE of 500-750 J/kg), strengthening wind
profiles/deep-layer shear will support the potential for organized
convection, including isolated supercells and/or short line segments
with an attendant threat for large hail, damaging winds, and perhaps
an isolated tornado.

..Thompson/Leitman.. 05/15/2022