SPC Mesoscale Discussion: Severe Potential… Watch Possible

SUMMARY…Isolated to widely scattered storms are expected to develop this afternoon over a portion of the southern Appalachian region. Some of the storms will become capable of producing downbursts winds and possibly some hail. Though a severe thunderstorm watch issuance is possible, it remains uncertain whether storm coverage will become sufficient.

DISCUSSION…This afternoon isolated storms are in the process of developing along an old modifying outflow boundary from northeast AL into middle and east TN. Other storms are expected to initiate over the higher terrain of east TN and the western Carolinas. The surface layer in vicinity of the outflow boundary continues to destabilize with diabatic warming boosting MLCAPE to 1500-2000 J/kg based on latest objective analysis. WV imagery shows a band of deeper ascent accompanying a vorticity maximum spreading southeast through east TN, along with a mid-level jet that is contributing to 35-45 kt effective bulk shear. The greater storm coverage will likely remain confined to eastern KY into northeast TN where vertical wind shear and instability are weaker. Storms developing farther south across much of the mesoscale discussion area will probably remain more isolated to widely scattered, but some of the storms could acquire mid-level updraft rotation, and a few instances of downburst wind and hail will be possible. In addition to expected isolated storm coverage, another potential limiting factor for a more robust severe threat is weak mid-level lapse rates. Nevertheless, convective trends will continue to be monitored next couple hours for a possible WW issuance over a portion of this region.

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Category: ALL POSTS, MescoScale Discussions