SPC MD 540

MD 0540 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR CENTRAL AND EASTERN OKLAHOMA INTO WESTERN ARKANSAS

Mesoscale Discussion 0540
NWS Storm Prediction Center Norman OK
0354 PM CDT Fri Apr 21 2017

Areas affected...Central and eastern Oklahoma into western Arkansas

Concerning...Severe potential...Watch possible 

Valid 212054Z - 212200Z

Probability of Watch Issuance...40 percent

SUMMARY...Some indications exist of an emerging hail threat in the
discussion area, although uncertainties exist regarding intensity
and coverage.

DISCUSSION...Convection has increased in western portions of the
discussion area over the past hour - likely aided by ascent
associated with an approaching vorticity maximum currently over
southwestern Kansas.  This activity is also likely aided by
continued advection of an elevated mixed layer atop shallow/stable
surface conditions in the wake of morning convection from an MCS
currently over northeast Arkansas.  Radar/observations suggest the
potential for small hail with the ongoing activity, perhaps
approaching 1" in diameter in the strongest cores.  

Some uncertainty exists with regard to coverage and intensity of
these storms through the evening.  Model guidance/objective analyses
suggest that convection will continue to persist in the region over
the next several hours given continued recovery/steepening of
mid-level lapse rates and the approaching vorticity maximum.  850mb
flow should increase some attendant to nocturnal enhancement of the
low-level jet, which may also increase convection throughout the
region.  Hail would be the primary threat, although damaging wind
gusts cannot be completely ruled out especially if storms can
organize into a linear complex.  Furthermore, near surface-based
convection may evolve near the outflow boundary, resulting in a
localized tornado threat.  Convective trends will continue to be
monitored for the possibility of a WW issuance.

..Cook/Goss.. 04/21/2017

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

ATTN...WFO...LZK...SGF...TSA...OUN...

LAT...LON   35219713 35939673 36499612 36589515 36509420 36449325
            36279286 35769266 35289280 34909322 34819413 34769517
            34489621 34449684 34499713 35219713 

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