SPC MD 1649

MD 1649 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF EASTERN OKLAHOMA AND ADJACENT WESTERN ARKANSAS INTO SOUTHEASTERN KANSAS AND SOUTHWESTERN MISSOURI

Mesoscale Discussion 1649
NWS Storm Prediction Center Norman OK
0418 AM CDT Mon Aug 31 2020

Areas affected...Parts of eastern Oklahoma and adjacent western
Arkansas into southeastern Kansas and southwestern Missouri

Concerning...Severe potential...Watch unlikely 

Valid 310918Z - 311115Z

Probability of Watch Issuance...20 percent

SUMMARY...A period of increasing, intensifying and organizing
thunderstorm development is possible through daybreak, which may
pose at least some risk for severe hail and wind.  While it is not
clear that a severe weather watch will be needed, trends are being
monitored.

DISCUSSION...Recent thunderstorm initiation to the west and
southwest of Tulsa OK appears in response to forcing for ascent
associated with warm advection and convergence, on the nose of a
strengthening southwesterly low-level jet (30-40 kt).  Model output
suggest that this is occurring within a weakness in mid-level
inhibition associated with warm elevated mixed-layer air (as
inferred from temperatures around 700 mb), where seasonably high
moisture content is contributing to most unstable CAPE on the order
of 2000-3000 J/kg.

Although mid-level winds are only modest in strength, veering with
height from lower to mid-levels, beneath a belt of 40-60+ kt
westerly high-level flow, is contributing to moderate to strong
deep-layer shear across the region.  

Given this environment, vigorous convective development is expected
to persist through daybreak, with an isolated supercell or two
capable of producing severe hail possible.  And there appears at
least potential for merging/upscale growing convection to organize
into one or two small clusters, which could eventually pose a risk 
for strong surface gusts.  

While this may be largely confined to east-central Oklahoma and
adjacent portions of Arkansas through 11-13Z, similar type
thunderstorm development may gradually spread north-northeastward,
near the eastern edge of the capping elevated mixed-layer, toward
the southern Missouri/Kansas state border vicinity.

..Kerr/Edwards.. 08/31/2020

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

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

LAT...LON   35989648 36589601 37609536 37599419 36959387 35919405
            34899379 34609491 34849585 35279651 35989648 

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from SPC Forecast Products http://www.spc.noaa.gov/products/md/md1649.html