Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1020 AM CST Thu Feb 22 2024
Valid 221630Z - 231200Z
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS PARTS OF SOUTHEASTERN ARKANSAS...NORTHERN MISSISSIPPI...AND
ADJACENT SOUTHWESTERN TENNESSEE...NORTHWESTERN ALABAMA...
...SUMMARY...
Strong thunderstorms may develop and overspread parts of the Mid
South this evening, and perhaps pose some risk for damaging wind
gusts and severe hail.
...Synopsis...
A couple of short wave perturbations of Arctic origins (currently
west of Hudson Bay) are forecast to continue to consolidate into a
vigorous digging short wave trough to the southwest through south of
Hudson Bay into the James Bay vicinity today through tonight. It
still appears that this will contribute to larger-scale mid/upper
trough amplification across the northern into mid-latitudes of
eastern North America (and accompanied by a significant cold front
crossing the Canadian/U.S. border into the northern Great Plains
through upper Great Lakes region by late tonight). In phase with
this regime, models indicate that the stronger westerlies across the
southern mid- and subtropical latitudes will trend broadly cyclonic
across the southern Great Plains through the Southeast, with one or
two consolidating embedded lower amplitude perturbations digging
from the central Great Plains/Ozark Plateau and lower Ohio Valley
through the lower Mississippi/Tennessee Valleys and southern
Appalachians by 12Z Friday.
While there may be some further deepening of surface troughing
shifting from the southern Great Plains through lower Ohio Valley
into the Southeast through Mid Atlantic, models indicate that any
embedded cyclogenesis will remain negligible, at least until it
shifts offshore Friday through Friday night. In the wake of
initially more amplified mid-level troughing now beginning to
accelerate away from the Atlantic Seaboard, boundary-layer
modification over the Gulf of Mexico has been slow. A limited
moisture return is ongoing on moderately strong southerly return
flow preceding the surface trough, but substantive further
improvement still appears unlikely through this period.
...Mid South and Ohio/Tennessee Valleys...
Observed and forecast soundings suggest that moistening supportive
of thunderstorm development, with large-scale ascent, is generally
occurring above a stable boundary, and beneath warm/dry capping
layers aloft, with profiles supportive of only weak CAPE. It
appears that this will remain the case as forcing for ascent begins
to support increasing thunderstorm activity ahead of the digging
mid-level troughing, southeast of the lower Ohio Valley through the
Tennessee Valley and portions of the lower Mississippi Valley later
today through tonight.
However, at least some model output, perhaps most notably the High
Resolution Rapid Refresh, suggests that a somewhat better moist (and
potentially unstable) inflow to the southwestern flank of this
forcing could enhance thunderstorm development this evening across
parts of the Mid South into Gulf States. The HRRR depiction of
convection includes an organizing cluster with 45+ kt rear inflow
developing near or above the 850-800 mb layer. Even if this
verifies, the potential efficiency of downward momentum transport to
the surface remains unclear based on forecast soundings, but a few
locally strong/damaging wind gusts might not be out of the question.
..Kerr/Squitieri.. 02/22/2024
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