Mesoscale Discussion 1069

Issued

Jun 17, 2017, 9:28 AM CDT (14:28 UTC)

Expired

Jun 17, 2017, 11:30 AM CDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

40%

Counties Howard County, AR, Little River County, AR, Montgomery County, AR, Polk County, AR, Scott County, AR, Sebastian County, AR, Sevier County, AR, Atoka County, OK, Cherokee County, OK, Choctaw County, OK, Haskell County, OK, Latimer County, OK, LeFlore County, OK, McCurtain County, OK, McIntosh County, OK, Muskogee County, OK, Pittsburg County, OK, Pushmataha County, OK, Sequoyah County, OK, Red River County, TX

The Western Arkansas radar (KSRX), 71 km from the middle of the area, began a volume at 14:30 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

911 
ACUS11 KWNS 171429
SWOMCD
SPC MCD 171428 
ARZ000-TXZ000-OKZ000-171630-

Mesoscale Discussion 1069
NWS Storm Prediction Center Norman OK
0928 AM CDT Sat Jun 17 2017

Areas affected...eastern Oklahoma...western Arkansas...and far
northeast Texas

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.

..Goss/Weiss.. 06/17/2017

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

ATTN...WFO...LZK...SHV...TSA...FWD...OUN...

LAT...LON   35709461 35429392 34559355 33709392 33559457 33629541
            33979606 34849610 35769565 35999498 35709461

Mesoscale Discussions in Oklahoma, 2017Mesoscale Discussions in Arkansas, 2017Mesoscale Discussions in Texas, 2017Every mesoscale discussion in 2017

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.