Severe Storm Outlook Narrative (AC)
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000
ACUS11 KWNS 282304
SWOMCD
SPC MCD 282304
TXZ000-290100-

Mesoscale Discussion 0358
NWS Storm Prediction Center Norman OK
0604 PM CDT Tue Mar 28 2017

Areas affected...Portions of central TX to the Edwards Plateau

Concerning...Severe potential...Watch possible

Valid 282304Z - 290100Z

Probability of Watch Issuance...40 percent

SUMMARY...Significant severe potential will exist with an evolving
supercell west-northwest of the Del Rio area. Otherwise, areas
across the Edwards Plateau to central TX are being monitored for
possible Watch issuance.

DISCUSSION...Low-level inflow and a midlevel mesocyclone continue to
intensify with a supercell storm around 55-60 nautical miles
west-northwest of the DFX RDA. This cell has remained anchored to a
subtle northeast-southwest-oriented boundary representing
differential mixing (moister air and shallower boundary layer to the
east). As the midlevel mesocyclone continues to organize and the
cell advances east-northeast, it will encounter surface dewpoints in
the upper 60s supporting MLCAPE around 2000-2500 J/kg per the DRT
21Z sounding. With around 50 kt of effective shear, and backed
surface winds enhancing low-level SRH and inflow, the risk for
significantly severe hail will exist as the cell eventually advances
east of the Rio Grande River in the next hour or so. While low-level
hodographs are relatively small, the backed surface winds and some
increase in low-level shear related to an approaching midlevel wave,
could support some uptick in the tornado potential.

Otherwise, weak convection is beginning to develop along subtle
north-south confluence axes northeastward across central TX. This
activity lies within the open warm sector, where adequately moist
boundary layer conditions and related low LFCs may support continued
deepening of convection. This may especially be the case later this
evening as stronger deep ascent approaches the area. While it is
unclear whether more robust convection were to evolve from this zone
of weak warm advection, there will be conditional severe potential.
Severe hail/wind would be the primary concerns with potential
supercell clusters in the moderately sheared environment, though the
strengthening low-level mass response could foster some increase in
tornado potential into the evening hours with more discrete
convection.

..Cohen/Thompson.. 03/28/2017

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

ATTN...WFO...FWD...EWX...SJT...

LAT...LON   29600138 29830125 29950098 30460027 30879993 31319918
            31529817 31059767 29719919 29440104 29600138



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