SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1005 AM CST Thu Feb 17 2022
Valid 171630Z - 181200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS CENTERED ON
CENTRAL/NORTHERN MS...WESTERN/MIDDLE TN...AND NORTHWEST AL...
...SUMMARY...
Severe thunderstorms are expected across portions of the Mid-South,
Tennessee Valley, and the lower Ohio Valley, mainly through this
evening. Damaging winds and tornadoes (at least a couple of which
may be strong) are the primary threats.
...Mid South/TN Valley into the OH Valley...
A shortwave trough over southeast KS/northeast OK will eject
northeast towards the Lower Great Lakes through tonight. Attendant
surface cyclone near the MO/AR border will deepen as it tracks
across the OH Valley towards the northern Appalachians. In advance
of a cold front trailing the surface cyclone, continued northward
moisture transport will result in mid-upper 60s boundary-layer
dewpoints reaching western portions of TN/AL and a plume of MLCAPE
from 500-1000 J/kg centered on eastern LA and MS. With
northern/eastern extent, lower quality boundary-layer moisture
and/or preceding rainfall will limit prospects for appreciable
surface-based instability.
Both pre-frontal and frontal convective bands are ongoing from the
Mid-South to the Sabine Valley. Cloud breaks in MS out ahead of this
activity should support adequate destabilization that broken bands
of storms with several embedded supercells should develop between
18-21Z across the Lower MS Valley and spread towards AL/Middle TN
into this evening. Despite the rather modest buoyancy and lapse
rates expected, highly enlarged and impressive low-level hodographs
will support potential for at least a couple strong tornadoes
centered on central to northern MS and adjacent portions of western
TN/AL.
Otherwise, a shallow/forced band of convection will likely accompany
the surface cyclone and trailing cold front just to the south.
Buoyancy will remain meager close to the OH River and some low-level
static stability should persist through the day into tonight.
However, thermodynamic profiles will be sensitive to changes of only
a few degrees, such that there is large variance in the potential
outcomes for coverage of damaging winds, in addition to a
line-embedded tornado or two as far north as the cyclone track
through this evening. Overnight, the severe threat will diminish
with northeast and east extent as a result of minimal buoyancy and
the stronger forcing for ascent no longer phasing with the remaining
weakly unstable warm sector to the south.
..Grams/Squitieri.. 02/17/2022
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