[BNAWX] Severe Storm Outlook Narrative

[EMWIN Server]

ACUS11 KWNS 251531
SWOMCD
SPC MCD 251530
TNZ000-NCZ000-VAZ000-KYZ000-251730-

Mesoscale Discussion 1251
NWS Storm Prediction Center Norman OK
1030 AM CDT Sun Jun 25 2023

Areas affected...Portions of far southern KY...middle/eastern
TN...western NC...and extreme southwestern VA

Concerning...Severe potential...Watch possible

Valid 251530Z - 251730Z

Probability of Watch Issuance...40 percent

SUMMARY...The threat for scattered damaging winds may gradually
increase over the next couple of hours. Watch issuance is possible.

DISCUSSION...A small cluster of convection is ongoing late this
morning across parts of south-central KY into middle TN. This
activity is loosely tied to thunderstorms that occurred overnight
and early this morning across the Upper Midwest. Well-below-severe
wind gusts have been observed at various ASOS and KY Mesonet sites
over the past hour or so, suggesting that the stronger velocities
noted on area radars are not yet reaching the surface. The 12Z
observed sounding from BNA shows a rich low-level airmass already in
place across middle TN, with mid 60s surface dewpoints and 14 g/kg
mean mixing ratio. A similar boundary-layer moisture profile will
also exist across eastern TN and vicinity, downstream of the ongoing
thunderstorms.

As daytime heating warms surface temperatures into the 80s across
this area over the next couple of hours, destabilization and erosion
of lingering MLCIN should quickly occur. MLCAPE exceeding 1000-1500
J/kg seems increasingly likely by 17Z, and convection may become
surface based by early afternoon. Although details regarding
convective evolution remain uncertain, there appears to be some
potential for ongoing thunderstorms to consolidate into a loosely
organized cluster while spreading east-southeastward across eastern
TN and vicinity this afternoon. A veering boundary-layer wind
profile observed on recent KOHX VWPs, and westerly winds
strengthening with height through mid levels, will foster around
25-35 kt of deep-layer shear, aiding in some convective
organization. Steepening low-level lapse rates ahead of the possible
cluster should allow for a more efficient transfer of strong/gusty
winds with downdrafts to the surface with time. Scattered damaging
winds may become an increasing concern through the early afternoon,
and isolated severe hail may occur with any supercell that can
form/persist on the southwest flank of the cluster. While not
immediately likely, observational trends will be monitored for
possible watch issuance by early afternoon.

..Gleason/Grams.. 06/25/2023

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

ATTN...WFO...GSP...MRX...JKL...LMK...OHX...

LAT...LON   35038500 35188572 35738629 36348604 36858546 36968483
            36888375 36718292 36468239 36178215 35778226 35458252
            35168292 34998370 35038500
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