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SPC United States Convective Summary



RSS Mesoscale Discussions from Storm Prediction Center

SPC MD 581

MD 0581 CONCERNING SEVERE POTENTIAL...WATCH POSSIBLE FOR PARTS OF SOUTHEASTERN OKLAHOMA...NORTHERN ARKANSAS...SOUTHERN MISSOURI...SOUTHERN INDIANA...WESTERN KENTUCKY
MD 0581 Image


Mesoscale Discussion 0581
NWS Storm Prediction Center Norman OK
0628 PM CDT Fri Apr 28 2017

Areas affected...Parts of southeastern Oklahoma...northern
Arkansas...southern Missouri...southern Indiana...western Kentucky

Concerning...Severe potential...Watch possible 

Valid 282328Z - 290200Z

Probability of Watch Issuance...60 percent

SUMMARY...A rapid increase in thunderstorm development, with at
least potential for severe hail, appears possible across the region
through the 8-10 pm CDT time frame.  One or more watches seem
probable by late evening.

DISCUSSION...Pronounced mid-level height rises and the northeastward
advection of elevated mixed layer air have tended to suppress
convective development either side of a stalled low-level baroclinic
zone across the Ozark Plateau into the the lower Ohio Valley. 
However, moistening to seasonably high levels into and above the
frontal zone (including 70F surface dew points to the south of the
front) has contributed to large potential instability, in the
presence of strong and sheared southwesterly deep layer mean flow
(including 60-80 kt at 500 mb).

Although mid/upper support for convective development is not readily
evident, it does appear that strengthening low-level warm advection
associated with increasing southerly 850 mb flow after sunset could
support a rapid increase in thunderstorm development.  This could be
aided by destabilization associated with radiational cooling atop
the elevated moist layer, most likely within the thermal gradient to
the north of the warmer and more strongly capping elevated mixed
layer air (probably north of the +10C isotherm at 700 mb).  This
activity may already be initiating across parts of southern
Illinois, and west southwestward development across southern
Missouri/northern Arkansas into southeast Oklahoma is expected
through 01-03Z.

..Kerr/Thompson.. 04/28/2017

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

ATTN...WFO...IND...PAH...MEG...LSX...LZK...SGF...SHV...TSA...

LAT...LON   38129088 38328891 38488775 37208737 36188988 35059228
            34309531 36289434 37489228 38129088 

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