SPC Mesoscale Discussion

SPC MD 1986

MD 1986 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR SOUTH-CENTRAL NEBRASKA AND INTO NORTHWEST KANSAS

Mesoscale Discussion 1986
NWS Storm Prediction Center Norman OK
0538 PM CDT Thu Sep 19 2019

Areas affected...south-central Nebraska and into northwest Kansas

Concerning...Severe potential...Watch unlikely 

Valid 192238Z - 192345Z

Probability of Watch Issuance...20 percent

SUMMARY...Local severe risk is evident across portions of
southwestern and into south-central Nebraska, where isolated
updrafts have quickly developed.  Risk should remain limited in area
and duration.

DISCUSSION...Latest visible satellite loop shows a couple of intense
updrafts which have developed near a subtle/westward-moving gravity
wave, that currently arcs from southwest Nebraska southeastward into
central Kansas, and then eastward into central Missouri.  The
thermodynamic environment within which the convection is developing
is quite favorable for robust/tall updrafts, given very steep lapse
rates aloft and a warm/moist boundary layer combining to yield 3000
to 4000 J/kg mixed-layer CAPE, per recent objective analysis.

With that said, deep-layer shear is relatively weak, despite
low-level veering, owing to weak westerly winds at mid levels.  The
relative lack of kinematic contribution to updraft intensity
therefore suggests only multicell organization for the most part,
with risk for hail and/or wind likely to remain local/isolated.  In
addition, the threat should remain fairly limited in overall
duration, with storms likely to diminish after dark as the boundary
layer cools/stabilizes.  Until then, hail up to golf ball size, and
wind gusts up to or slightly exceeding severe criteria will be
possible.

..Goss/Edwards.. 09/19/2019

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...GID...LBF...GLD...

LAT...LON   41619871 40219862 39549931 39900073 41320143 41650095
            41809987 41619871