Mesoscale Discussion 1145
NWS Storm Prediction Center Norman OK
0745 PM CDT Wed Jun 19 2019
Areas affected...portions of central Kentucky...northern Tennessee
Concerning...Severe Thunderstorm Watch 403...
Valid 200045Z - 200245Z
The severe weather threat for Severe Thunderstorm Watch 403
SUMMARY...Severe threat continues with Severe Thunderstorm Watch
0403. Damaging wind gusts will be the primary threat, particularly
with a forward-propagating line segment. Large hail may also occur
with transient supercell structures in northern Tennessee. The
severe threat may gradually subside after sunset with the onset of
DISCUSSION...An organized MCS is currently moving across central KY
into northern TN, where damaging wind gusts have been reported over
the past few hours. This line segment will continue to propagate
eastward for at least a few more hours, where 1000-1500 J/kg MLCAPE
remain, along with modest low-level shear (100-150 m2/s2 0-1km SRH
per latest mesoanalysis and RAP forecast soundings). The low-level
shear in place may help to counterbalance the MCS- generated cold
pool, preventing the leading line convection from becoming undercut.
As such, the line is expected to persist through at least the
remainder of the afternoon.
At the same time, more semi-discrete, cellular structures (perhaps
transient supercells) have been noted across northern into middle
Tennessee. The cold pools associated with these storms have recently
begun to merge, suggesting that a more linear convective mode seems
to be taking place. Still, remnant semi-discrete updrafts with
sustained mid-level rotation may produce isolated severe hail.
After sunset, nocturnal cooling will likely result in stabilization
of the boundary layer, where increasing inhibition may contribute to
a gradual downward trend in the severe threat.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 36168860 36438737 36958656 37888644 38168516 38248425
38108368 37688352 36698355 36148387 35728525 35588598
35688715 35768820 36168860