Mesoscale Discussion 1069
NWS Storm Prediction Center Norman OK
0928 AM CDT Sat Jun 17 2017
Areas affected...eastern Oklahoma...western Arkansas...and far
Concerning...Severe potential...Watch possible
Valid 171428Z - 171630Z
Probability of Watch Issuance...40 percent
SUMMARY...A small cluster of strong/locally severe storms will
continue moving south across the eastern Oklahoma vicinity,
accompanied by local risk for marginally severe hail/wind. Though
at this time convection is expected to remain limited in coverage,
and eventually decreasing in intensity over the 1-2 hours, WW may be
required if storms persist/increase in coverage and intensity.
DISCUSSION...Latest radar loop continues to show a small cluster of
vigorous convection moving southward across parts of eastern
Oklahoma, within an axis of low- to mid-70s dewpoints and associated
maximum in mixed-layer CAPE (around 2000 J/kg). Area RAOBs and VWPs
show rather modest -- though veering -- flow with height, along with
a slowly diminishing west-southwesterly low-level jet.
A plume of very warm/dry air near 850 mb is being advected slowly
eastward, and thus capping will limit any potential for westward
expansion of storms along the southwestward-moving outflow.
Additionally, the morning SHV RAOB also shows substantial capping,
suggesting that southward progression of the convection will also
likely remain limited. As such, a rather small spatial area for
continuation of the ongoing convection is suggested. Additionally,
with relatively modest flow aloft to limit overall organization
potential, ongoing severe risk is expected to remain limited in
magnitude, and contained areally and temporally. Still, should
diurnal heating south of the convection in a relatively cloud-free
zone over southeast Oklahoma allow storms to persist, and increase
somewhat in coverage, WW would be considered.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 35709461 35429392 34559355 33709392 33559457 33629541
33979606 34849610 35769565 35999498 35709461