[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 121439
SWOMCD
SPC MCD 121439
GAZ000-TNZ000-ALZ000-KYZ000-MSZ000-121645-

Mesoscale Discussion 1963
NWS Storm Prediction Center Norman OK
0939 AM CDT Sat Aug 12 2023

Areas affected...portions of western into middle TN...northern
AL...and vicinity

Concerning...Severe potential...Severe Thunderstorm Watch likely

Valid 121439Z - 121645Z

Probability of Watch Issuance...80 percent

SUMMARY...Increasing threat for damaging wind gusts and hail this
morning into this afternoon. Watch issuance is likely.

DISCUSSION...Convective redevelopment is ongoing in southern KY and
northern TN along a remnant outflow boundary from a nocturnal
thunderstorm complex. Additional updraft development is observed
just ahead of the outflow in a warm-advection regime. This
convection is expected to continue intensifying as the system
propagates to the southeast through western/middle TN and into
northern AL and the vicinity throughout the morning.

The expected intensification will be supported by a local
environment characterized by MLCAPE around 3000 J/kg (based on a
blend of current observations with the observed 12z BNA sounding).
Bulk northwesterly shear will support deep updraft intensification
as the system propagates to the southeast. Steep mid-level lapse
rates are in place (over 8 C/km), which will aid strong downdraft
development and localized hail swaths. The environment ahead of the
system should continue gradually destabilizing due to a combination
of diurnal heating (tempered somewhat by an expanding cirrus canopy)
and southerly warm-air advection. This should lead to inhibition
erosion within the next couple of hours, further supporting a threat
for severe wind gusts. The greatest short-term threat will reside in
western/middle TN with a combination of reinvigorated forced
convection along the outflow as well as any storms forming ahead of
the outflow. The threat will gradually shift toward northern AL
later this morning into the afternoon as storms continue to congeal
and associated outflow expands southeast. A Severe Thunderstorm
Watch is anticipated within the next hour or so to address these
threats.

..Flournoy/Smith.. 08/12/2023

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...MRX...FFC...LMK...OHX...BMX...HUN...PAH...MEG...

LAT...LON   33158527 33218688 33848807 35388897 36128912 36748856
            37038756 36788629 35948518 34698479 33708485 33158527
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