Mesoscale Discussion 1650
NWS Storm Prediction Center Norman OK
0108 PM CDT Tue Aug 06 2019
Areas affected...eastern Missouri and into southern
Illinois...southwestern Indiana...and western Kentucky
Concerning...Severe potential...Watch likely
Valid 061808Z - 062015Z
Probability of Watch Issuance...80 percent
SUMMARY...Thunderstorms are forecast to increase in coverage over
the next 1-2 hours over the mid Mississippi and lower Ohio Valley
area, along with an associated increase in severe potential. A
watch will likely be required.
DISCUSSION...Latest visible satellite imagery shows an increase in
cu/cb across parts of eastern Missouri, northwest of the St. Louis
area. The increase is occurring near a very weak/subtle frontal
wave, associated with a mid-level disturbance moving southeastward
across northwestern Missouri.
With a very moist airmass undergoing continued heating/
destabilization (mixed-layer CAPE now exceeding 2500 to 3000 J/kg
across much of the discussion area), an increase in convective
development is expected to continue -- resulting in eventual
strong/locally severe storm development.
The latest LSX (St. Louis) WSR-88D VWP shows low-level flow veering
to northwesterly in the lowest 1km, and then a roughly
unidirectional northwesterly profile that increases in speed with
height. This kinematic environment supports organized,
southeastward-moving storms, with upscale growth into sustained
storm clusters expected. Locally damaging wind gusts will likely be
the primary risk, though hail is also possible. Given the
expected/gradual increase in severe potential, a WW will likely be
required in the next hour or so.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 39169132 39279082 39048936 38958805 38178753 37158773
36678865 36718970 37989101 39169132