|Mesoscale Discussion 66|
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Mesoscale Discussion 0066
NWS Storm Prediction Center Norman OK
0708 PM CST Tue Jan 17 2017
Areas affected...Coastal plain of Texas
Concerning...Severe potential...Watch unlikely
Valid 180108Z - 180315Z
Probability of Watch Issuance...20 percent
SUMMARY...Marginal severe hail and perhaps a tornado can be expected
along a frontal zone over the coastal plain of Texas this evening.
Tornado watch is not anticipated at this time.
DISCUSSION...Sustained low-level warm advection appears to be the
primary forcing mechanism for slowly maturing thunderstorms across
the western coastal plain of TX. Over the last hour or so
convection has gradually deepened over Webb/Duval/Jim Hogg counties
and updrafts are now producing lightning within several clusters.
00z sounding from CRP is very moist with PW on the order of 1.75
inches and surface dew points across the warm sector are in the
lower 70s. While low-level shear is not that strong...more than
adequate deep-layer flow exists across this region for sustaining
rotating updrafts. There is some concern that a few supercells will
evolve near the quasi-stationary frontal zone and this low-level
feature may locally enhance the possibility for a tornado along a
corridor from Jim Hogg county, northeast toward Matagorda county
this evening. At this time it appears the severe coverage will be
too sparse to warrant a tornado watch.
LAT...LON 27629904 28689728 29149619 28749588 27509744 26979866
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