SPC Mesoscale Discussion: Severe Potential… Watch Possible

SUMMARY…Isolated severe thunderstorms with primarily a strong to damaging wind threat may develop this afternoon. Watch issuance is possible.

DISCUSSION…Storms should continue to strengthen across middle into eastern TN this afternoon along a trailing boundary extending southward from a MCV in western/central KY. It appears that large-scale forcing for ascent attendant to an upper trough over the mid MD Valley and Upper Midwest may only glance this region. Even so, low-level convergence along the trailing outflow boundary should prove sufficient for additional convective development over the next couple of hours as MLCAPE increases into the 1000-2000 J/kg range downstream. An unseasonably strong belt of 40-50 kt southwesterly winds is present around 700 mb from middle/eastern TN into AL and much of GA this afternoon per VWP estimates from area radars and 17Z mesoanalysis. As diurnal mixing of the boundary layer continues across this region, low-level lapse rates will steepen further. Strong to damaging winds may occur with storms as the enhanced flow present at 700 mb reaches the surface through convective downdrafts. Relatively greater storm coverage is anticipated across middle/eastern TN this afternoon in closer proximity to the upper trough, although isolated development may also occur farther south into northeastern AL and northern/central GA. A Severe Thunderstorm Watch may eventually be needed this afternoon for some part of this region depending on radar trends.

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