SPC MD 1724

MD 1724 CONCERNING SEVERE POTENTIAL...WATCH UNLIKELY FOR PARTS OF COASTAL NORTH CAROLINA AND SOUTHEAST VIRGINIA

Mesoscale Discussion 1724
NWS Storm Prediction Center Norman OK
0801 PM CDT Tue Sep 29 2020

Areas affected...Parts of coastal North Carolina and southeast
Virginia

Concerning...Severe potential...Watch unlikely 

Valid 300101Z - 300300Z

Probability of Watch Issuance...20 percent

SUMMARY...At least some further increase in potential for locally
damaging wind gusts, and perhaps a tornado or two, appears possible
with an evolving squall line approaching North Carolina and
southeastern Virginia coastal areas through 11 PM-1 AM EDT.  While
it is not yet clear that a severe weather watch will be needed,
trends will continue to be monitored for this possibility.

DISCUSSION...As a significant mid-level short wave trough pivots
into the central/southern Appalachians vicinity this evening, a
surface low may gradually consolidate and deepen across southeastern
Virginia, along a cold front approaching southern Mid Atlantic
coastal areas.  Based on latest RAOB and VWP data, southerly flow
around 850 mb may already be increasing near North Carolina coastal
areas.  Through 03-05Z, further strengthening (to 50-60+ kt) is
forecast across the North Carolina Outer Banks into the vicinity of
southeastern Virginia coastal areas. 

Model forecast soundings indicate that this will contribute to
enlarging, clockwise-curved low-level hodographs in the warm, moist
sector characterized by lower/mid 70s surface dew points, as a
frontal convective band overspreads the region.  This band has been
generally shallow and weak, with little lightning, largely due to
relatively warm mid-levels with weak lapse rates limiting
boundary-layer CAPE.  

While instability is not likely to improve much through the evening,
it is possible that strengthening low-level shear could contribute
to increasingly organized convection, with occasionally
strengthening low-level mesocyclones.  These may be accompanied by
at least somewhat greater potential for damaging surface gusts, and
perhaps a couple of tornadoes, than has existed the past few hours.

..Kerr/Hart.. 09/30/2020

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

ATTN...WFO...AKQ...MHX...

LAT...LON   35247752 35997717 37027680 37787580 36847571 35347556
            34227742 35247752 

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from SPC Forecast Products http://www.spc.noaa.gov/products/md/md1724.html