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Day 1 Convective Outlook  
NWS Storm Prediction Center Norman OK
0800 PM CDT Wed May 18 2022

Valid 190100Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Damaging winds and isolated large hail will be possible across parts
of the central high Plains into northern sections of the southern
Plains this evening into tonight. Isolated damaging wind gusts, hail
and perhaps a brief tornado will also be possible in parts of the
southern Appalachians early this evening.

...Southern and Central High Plains...
The latest water vapor imagery shows west-northwest mid-level flow
over much of the central U.S. with a subtle shortwave trough located
over the southern and central High Plains. At the surface, a 1001 mb
low is located in northwest Texas, with backed easterly surface
winds over much of Oklahoma and Kansas. The backed flow was
coincident with a relatively moist airmass, mainly from Oklahoma
northward into central Kansas. A drier airmass was located in the
southern and central High Plains where surface dewpoints were in the
40s and 50s F. The latest RAP has an east-to-west axis of moderate
to strong instability extending across northern Oklahoma. The
western edge of moderate instability is located in the Texas
Panhandle northward into western Kansas and southeast Colorado,
where a co*plex of thunderstorms is ongoing. This cluster of storms
is expected to move east-southeastward down the axis of moderate
instability this evening, and appears likely to persist after
midnight.

RAP forecast soundings this evening along the forecast track of the
MCS from southwest Kansas into northwest Oklahoma suggest that the
environment will be more favorable with eastward extent. This should
enable the MCS to remain organized for much of the evening. As a
cold pool develops with the current cluster, the wind damage threat
will likely increase along the leading edge of the MCS. A few wind
gusts over 65 knots will be possible, especially if a faster moving
bowing line segments can develop. As the MCS encounters more
instability further east-southeast, isolated supercells with large
hail will beco*e possible. The severe threat associated with the
stronger cells may be able to produce isolated wind damage and hail
after midnight, as the MCS tracks eastward into southeast Kansas and
northeastern Oklahoma.

...Southern Appalachians...
The latest water vapor imagery shows a subtle shortwave trough
moving east-southeastward across the Ohio and Tennessee Valleys. At
the surface, a cold front is moving through the lower Ohio Valley
with a somewhat moist airmass in place over the southern
Appalachians and Tennessee Valley. An axis of moderate instability
is analyzed from middle Tennessee northward into western/central
Kentucky with the eastern edge of the stronger instability located
in the western foothills of the Appalachians. A small cluster of
strong to severe thunderstorms was ongoing in southeast Kentucky
along the instability gradient. These storms were located along the
southern edge of a belt of strong mid-level flow, which was creating
moderate deep-layer shear. This co*bined with enhanced low-level
shear associated with a 30 to 40 knot speed max near 850 mb, may be
enough to continue a supercell threat early this evening. Supercells
should be capable of isolated damaging wind gusts, and perhaps a
brief tornado over the next hour or two. But the severe threat
should beco*e marginal as the storms move eastward into the higher
terrain where instability is much weaker.

..Broyles.. 05/19/2022