SPC MD 594

MD 0594 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR NORTH-CENTRAL TX...FAR SOUTH-CENTRAL OK

Mesoscale Discussion 0594
NWS Storm Prediction Center Norman OK
0210 PM CDT Sat Apr 29 2017

Areas affected...North-central TX...Far south-central OK

Concerning...Severe potential...Watch possible 

Valid 291910Z - 292115Z

Probability of Watch Issuance...60 percent

SUMMARY...Thunderstorms capable of damaging wind gusts and hail are
expected to develop along and/or just head of the frontal boundary
during the next hour or two. A watch may be needed to address the
potential severe threat posed by these storms.

DISCUSSION...Recent visible satellite imagery shows attempts at deep
convection in Grayson, Collin, and Fannin counties, within a broad
area of confluence ahead of the front. 18Z FWD sounding revealed
modest capping (i.e. MLCIN near -30 J/kg) remains in place over the
region, which matches with the generally flat appearance of the cu
across the majority of region. However, increasing ascent associated
with the approaching upper system, continued moistening of the
low-levels, and persistent low-level convergence along and just
ahead of the front will likely combine to overcome the capping and
support convective initiation within the next hour or two.  

18Z FWD sounding sampled an environment characterized by MLCAPE in
excess of 2000 J/kg and strong low-level shear (0-1 km and 0-3 km
shear of 28 kt and 55 kt, effectively). Parallel orientation of the
bulk shear vector to the cold front suggests that a linear mode is
favored and upscale growth will likely happen quickly once
convective initiation occurs. As a result, the primary severe hazard
is likely damaging wind gusts. Even so, given steep mid-level lapse
rates and the related strongly instability, some hail is possible,
particularly with any initial development. Trends across the region
will be monitored closely for potential watch issuance.

..Mosier/Weiss.. 04/29/2017

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

ATTN...WFO...TSA...FWD...OUN...

LAT...LON   33249715 34149678 34039584 32279599 31909711 32159753
            33249715 

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