Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 220102
SWOMCD
SPC MCD 220102
TXZ000-220330-

Mesoscale Discussion 0809
NWS Storm Prediction Center Norman OK
0802 PM CDT Sun May 21 2017

Areas affected...South Texas

Concerning...Severe potential...Watch possible

Valid 220102Z - 220330Z

Probability of Watch Issuance...40 percent

SUMMARY...A severe threat will be possible this evening across south
Texas. Wind damage and isolated large hail will be the primary
threats. Weather watch issuance could be needed across south Texas
if the current severe threat increases.

DISCUSSION...The latest surface analysis shows a 999 mb low in
northern Mexico with a trough extending eastward from the low to
near the Gulf Coast and then northward into south Texas. Low-level
convergence appears to be maximized along the surface trough which
is supporting thunderstorm development. Surface dewpoints in south
Texas are in the lower to mid 70s F and MLCAPE is estimated to be in
the 1500 to 2500 J/kg range. This combined with moderate deep-layer
shear evident on regional WSR-88D VWPS and steep lapse rates will be
favorable strong updrafts with isolated large hail potential. Backed
surface winds to the east are also contributing to low-level shear
which will could aide the developing of bowing structures with a
wind damage threat. The bowing line segment that is near the Rio
Grande River and is currently moving into south Texas at 25 to 30
kt. This should keep any wind damage threat isolated. Nevertheless,
trends will continue to be monitored and a weather watch is still
being considered.

..Broyles/Hart.. 05/22/2017

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

ATTN...WFO...CRP...BRO...

LAT...LON   27099727 26759723 26309707 25949709 25879754 25929847
            26269908 27009962 27369954 27529912 27609778 27389721
            27099727




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