Mesoscale Discussion 1054
NWS Storm Prediction Center Norman OK
1245 PM CDT Fri Jun 16 2017
Areas affected...Portions of southeast MO...southern IL...western
KY...western TN...northeast AR
Concerning...Severe potential...Watch unlikely
Valid 161745Z - 162015Z
Probability of Watch Issuance...20 percent
SUMMARY...There will exist the potential for isolated severe
thunderstorms through the afternoon across parts of the lower Ohio
Valley region and Mid-South. While environmental and convective
trends will continue to be monitored, the issuance of a Watch is
DISCUSSION...Ascent across the northeastern quadrant of an MCV
crossing eastern AR, and along the edges of MCV-related multi-
layered cloud canopies where differential-heating-induced
baroclinicity is being diurnally enhanced, will continue to foster
an increase in convective coverage across the area. Inflow buoyancy
for this activity is strong (e.g., 2000-3000 J/kg of MLCAPE), owing
to strong surface heating amid dewpoints in the lower/middle 70s.
This will likely support robust updrafts capable of isolated severe
hail/wind, with local convective clustering / cold-pool amalgamation
focusing damaging-wind potential.
Eastward propagation of this activity will be favored by
preferential development of regenerative convection into the higher
theta-e air east of the ongoing convection. However, deep shear is
quite weak across the region, with effective shear magnitudes
generally below 25 kt. This should tend to limit the severe
coverage. Furthermore, as storms approach a minimum in deep moisture
with additional eastward extent across the lower Ohio Valley, they
may tend to weaken owing to dry-air entrainment and eventual
ingestion of weaker buoyancy as boundary-layer moisture mixes out.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 36038863 35698926 35858991 36779007 37869063 38388990