SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1147 PM CST Mon Feb 21 2022
Valid 221200Z - 231200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
MISSISSIPPI VALLEY TO THE LOWER OHIO VALLEY...
...SUMMARY...
Severe thunderstorms associated with an isolated tornado threat,
wind damage, and large hail will be possible Tuesday from Arkansas
northeastward into the lower Ohio Valley. Severe thunderstorms and
a tornado risk are also possible across mainly parts of Mississippi
and Alabama Tuesday evening into the overnight.
...Lower MS Valley to Lower OH Valley...
Low-amplitude mid-level short-wave trough over the southern Plains
is forecast to eject northeast into the OH Valley Tuesday, slightly
suppressing the height fields north of the OH River. This feature
will encourage a surface low to track northeast across MO/IL into
southern ON by early evening. Warm sector will modify as it is drawn
northeast ahead of this low-pressure system, but adequate buoyancy
will likely surge across western KY into extreme southern IN
supporting some severe threat into this region.
Late this evening, a 500 mi elongated corridor of convection was
observed from west TX-southeast OK-western AR. This activity should
continue through sunrise and be ongoing at the start of the period
as an intense LLJ (70+ kt) will be focused over AR by this time.
Further strengthening to near 90kt is forecast by mid day as the LLJ
translates downstream across KY into southwest OH. Very strong wind
fields are of particular concern but poor lapse rates and weak
buoyancy will negate this flow field to some degree. Forecast
soundings exhibit very strong flow just off the surface and this
will warrant extending severe probabilities a bit downstream to
account for the possibility of damaging winds with convection.
Complex storm mode will be noted through the period with clusters,
potential line segments, and possible embedded supercells expected
from northern AR into KY. Damaging winds should be the primary
threat but a few tornadoes appear possible with supercell
structures.
While the primary short wave/forcing will spread across the OH
Valley by late afternoon, some boundary-layer heating will be noted
ahead of the front across western TN into MS. This will aid buoyancy
and the potential for isolated supercells, despite the negligible
large-scale support at this latitude by late afternoon. A secondary
corridor of convection should evolve across this region prior to
frontal passage and wind fields will support supercells. Wind is
possible with this activity along with some tornado potential.
Frontal convection will linger through the overnight hours across
TN, trailing southwest into central MS.
..Darrow/Lyons.. 02/22/2022
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