Mesoscale Discussion 0226
NWS Storm Prediction Center Norman OK
1127 AM CDT Tue Mar 24 2020
Areas affected...Parts of northeastern Arkansas and the Missouri
Bootheel into western Tennessee and adjacent portions of the Mid
Concerning...Severe potential...Watch possible
Valid 241627Z - 241830Z
Probability of Watch Issuance...40 percent
SUMMARY...A gradual increase in severe weather potential appears
possible through 2-3 PM CDT, in association with an evolving cluster
of thunderstorms overspreading the region. It is not clear that a
watch is needed in the near term, but trends will continue to be
monitored for this possibiity.
DISCUSSION...At least some increase/intensification of thunderstorm
development appears ongoing near the northeastern Arkansas/Missouri
state border area into northwestern Tennessee. This convection is
rooted within a zone of enhanced lower/mid tropospheric warm
advection, roughly near the nose of a 40 kt southwesterly 850 mb
jet, and within the left exit region of an associated 80 kt westerly
500 mb jet streak. The mid-level jet may weaken some into mid
afternoon, but is forecast to continue to propagate from north
central Arkansas through western into middle Tennessee by 19-20Z.
Most unstable CAPE within the inflow layer of the convection may be
increasing in excess of 500 J/kg. Coupled with strong shear within
the convective layer, the environment may be conducive to support
gradual further upscale convective growth and organization during
the next few hours.
Based above a residual surface-based stable layer, large hail seems
the primary initial severe hazard. However, downstream, the surface
front already appears to have shifted to the north of Memphis TN,
Muscle Shoals and Huntsville AL, and, at some point, the potential
for strong surface gusts may increase as activity becomes
increasingly rooted closer to the surface.
While convection may largely remain focused just to the cool side of
the surface front, into areas near/south of the western
Kentucky/Tennessee border, it is possible that storms on the
southwestern flank of the evolving cluster may eventually become
rooted within the unstable boundary layer, along and just south of
the front. If/when this occurs, sizable clockwise curved low-level
hodographs probably will support a risk for supercells with
potential to produce tornadoes.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 36078979 36308920 36628907 36678788 36668673 35538674
34868790 34839016 35619056 36078979