SPC MD 753


MD 0753 Image

Mesoscale Discussion 0753
NWS Storm Prediction Center Norman OK
0144 PM CDT Thu May 28 2020

Areas affected...Edwards Plateau/Hill Country vicinity and adjacent
Rio Grande Valley

Concerning...Severe potential...Watch possible 

Valid 281844Z - 282045Z

Probability of Watch Issuance...40 percent

SUMMARY...Further intensification of thunderstorms appears likely
across the Edwards Plateau into the Hill Country and Rio Grande
Valley through 3-5 PM CDT.  This will be accompanied by a risk for
severe hail.  There appears at least some potential for the
evolution of an increasingly organized cluster of storms, which
could become capable of producing strong surface gusts.  If/when
this becomes more certain, a severe weather watch may be issued.

DISCUSSION...Mid/upper support for convective development remains
unclear, but vigorous thunderstorms have initiated across the San
Angelo area.  Low-level convergence appears weak, but activity
appears to be largely focused along the leading edge of low-level
cooling and drying advancing across and south of the Texas South

Deep-layer mean ambient flow across this region appears generally
weak, northerly at 10-20 kt, but there may be a belt of somewhat
stronger winds at mid-levels (on the order of 30 kt around 500 mb),
contributing to at least modest shear.  

Of particular note, surface dew points are still in the the mid 60s
to around 70f to the south of the ongoing storms, where
boundary-layer heating is contributing to large CAPE (3000+ J/kg) in
the presence of relatively steep lower/mid tropospheric lapse rates.
 With the shear allowing for at least modest inflow from this
environment into the developing storms, there appears potential for
considerable updraft intensification during the next few hours.

Appreciable upscale convective growth may await the development of a
more substantive surface cold pool, but, based on thermodynamic
profiles, this appears possible.  If/when this occurs, an
increasingly organized convective system could evolve, accompanied
by strengthening rear inflow and potential for strong surface gusts.

Otherwise, the primary potential severe hazard with strongest storms
is probably severe hail, as activity tends to gradually propagate
toward the San Antonio and Del Rio vicinities.

..Kerr/Hart.. 05/28/2020

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


LAT...LON   31350225 31480143 31700037 31399903 30089834 29439832
            29189922 29360068 29980166 30300219 31350225 

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