Mesoscale Discussion 0696
NWS Storm Prediction Center Norman OK
0137 PM CDT Thu May 11 2017
Areas affected...East Texas...Far Northwest Louisiana...Southwest
Arkansas...Far Southeast Oklahoma
Concerning...Severe potential...Watch likely
Valid 111837Z - 112100Z
Probability of Watch Issuance...80 percent
SUMMARY...A severe threat appears likely to develop across parts of
east Texas extending northeastward into the Arklatex. Large hail and
wind damage will be the primary threats. Weather watch issuance will
probably be needed by 20Z.
DISCUSSION...The latest surface analysis shows a 1009 mb low over
central Oklahoma with a moist airmass located to the east and
southeast of the low across the Arklatex into east Texas. Surface
dewpoints are generally in the upper 60s and lower 70s F along this
corridor with MLCAPE values estimated in the 1500 to 2500 J/kg range
by the RAP. Scattered thunderstorms are already ongoing along the
instability corridor. This convection is forecast to gradually
intensify and expand in coverage as surface temperatures continue to
warm this afternoon. In addition, moderate deep-layer shear is
present across much of the moist sector. The WSR-88D VWP at
Shreveport appears representative of the environment across the MCD
area, showing 0-6 km shear of 40 to 45 kt with some directional
shear in the low-levels. This suggests that supercell development
will be possible with cells that remain discrete. Steep mid-level
lapse rates approaching 8.0 C/km will be favorable for isolated
large hail with the stronger rotating updrafts. Some of the storms
may also organize into short-line segments with potential for
damaging wind gusts.
..Broyles/Guyer.. 05/11/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LZK...LCH...SHV...TSA...HGX...FWD...
LAT...LON 30869480 30629601 30789692 31199718 31999684 33179582
34109548 34369476 34259387 33659344 32809355 31649389
30869480
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