SPC MD 1649


MD 1649 Image

Mesoscale Discussion 1649
NWS Storm Prediction Center Norman OK
1059 AM CST Thu Nov 15 2018

Areas affected...Far eastern North Carolina...Outer Banks vicinity

Concerning...Severe potential...Watch unlikely 

Valid 151659Z - 151930Z

Probability of Watch Issuance...20 percent

SUMMARY...Some risk for thunderstorms accompanied by potentially
damaging wind gusts, or perhaps a tornado, may develop across parts
of far eastern North Carolina and the Outer Banks area through 3-5
PM EST.  Due to the isolated, somewhat marginal, nature of this
threat, it is not clear that a severe weather watch will be needed,
but trends will be monitored.

DISCUSSION...An area of ongoing convection and embedded thunderstorm
activity now east of the North Carolina coast appears supported by
warm advection and convergence along the surface warm front, and a
southward trailing pre-cold frontal low-level confluence zone.  This
also appears to be occurring beneath strongest difluence aloft,
which is forecast to continue developing north/northeastward through
early/mid afternoon.  As it does, strongest boundary-layer based
thunderstorms appear likely to pass to the south/east of the Outer
Banks vicinity.

However, increasing surface pressure falls are now underway across
much of eastern North Carolina into Virginia, and a developing area
of low pressure along the surface frontal zone appears likely to
migrate inland near/east of Wilmington, before continuing across the
coastal plain toward the Hampton Roads area through 20-22Z.  As this
occurs, backing and strengthening near surface flow may allow for an
influx of seasonably high boundary layer moisture content across the
Outer Banks area and nearby coastal areas during the next few hours.
 Despite generally weak to modest low/mid-level lapse rates,
forecast soundings suggest that this may be sufficient to contribute
to mixed-layer CAPE on the order of 500-1000 J/kg.

Given this destabilization, there may be a window of opportunity for
isolated renewed thunderstorm development across far eastern North
Carolina and the Outer Banks.  Although it appears that the
clockwise curvature in the low-level hodographs may decrease by this
time, momentum/shear beneath 50+ kt southerly 850 flow will still
provide some potential for strong wind gusts, if not an isolated
tornado or two.

..Kerr/Hart.. 11/15/2018

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


LAT...LON   36437637 36557589 36057520 35197540 34487629 34357735
            35187711 36437637 

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