Mesoscale Discussion 0247
NWS Storm Prediction Center Norman OK
0211 PM CST Wed Mar 01 2017
Areas affected...Portions of east-central MS...central/northern
AL...northern GA...southeastern TN...western NC
Concerning...Tornado Watch 57...
Valid 012011Z - 012215Z
The severe weather threat for Tornado Watch 57 continues.
SUMMARY...The risk for severe storms continues spreading eastward
across portions of the southern Appalachians to the TN Valley region
to central MS, and will continue spreading eastward into the late
afternoon hours.
DISCUSSION...Semi-discrete supercells and thunderstorm clusters
continue near/just ahead of a front from eastern TN to central MS.
Straight hodographs indicated by area VAD wind profiles suggest
that -- despite adequate crosswise vorticity for rotating storms
associated with 50-65 kt of deep shear -- streamwise vorticity is
quite limited. As such, storm-relative motion data from single-site
radars suggest that any low-level mesocyclones have remained weak.
Nevertheless, with mid-level lapse rates around 7-8 C/km sampled by
the Jackson and Birmingham 18Z soundings -- suggesting strong
convective-scale accelerations and attendant vertical vorticity
stretching -- mid-level mesocyclones have been persistent with the
most intense cells. Large hail will remain possible with this
activity as it spreads eastward, and sporadic damaging-wind gusts
may also occur. While the tornado risk remains non-zero for any
supercell structures that more substantially deviate to the right of
the mean flow (given adequate low-level moisture), the lack of
ambient hodograph curvature should limit the efficiency of low-level
mesocyclone development. The severe risk will diminish northwest of
the aforementioned activity.
..Cohen.. 03/01/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MRX...FFC...BMX...HUN...JAN...
LAT...LON 32648978 33558844 35448459 34948381 34198444 32948767
32648880 32648978
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