Mesoscale Discussion 0400
NWS Storm Prediction Center Norman OK
0954 AM CDT Fri Apr 19 2019
Areas affected...Eastern North Carolina...northeast South Carolina
Concerning...Severe potential...Watch possible
Valid 191454Z - 191630Z
Probability of Watch Issuance...40 percent
SUMMARY...Scattered storms capable of isolated damaging wind gusts
and perhaps a tornado or two are possible in the next few hours.
Given the sparse nature of the severe threat, a WW issuance is
uncertain in the near term, though a WW may be needed in association
with upstream convection later this afternoon.
DISCUSSION...A surface low continues to deepen across eastern
Tennessee, triggering a mass response in the low-level flow fields,
with a broad low-level jet transporting deep (925-850 mb) moisture
across the Coastal Piedmont Region. A confluence band, delineating
the axis of the aforementioned low-level moisture transport, has
triggered convection within the past few hours, within a
Currently, the ambient thermodynamic environment is characterized by
deep low-level moisture, but with mediocre low and mid-level lapse
rates (around 5.5-6.0 C/km throughout a deep tropospheric layer),
with around 500 J/kg MLCAPE common across the area. Regarding the
kinematic environment, effective bulk shear values of 40-50 knots
and 250 m2/s2 effective SRH is in place across much of the
Carolinas. Given further intensification of the surface low, the
aforementioned shear environment is expected to stay in place over
the next several hours. In addition, with further heating, MLCAPE
may increase to 1000 J/kg. This buoyancy/shear parameter space may
support organized convection, including rotating cells capable of
producing isolated damaging wind gusts and perhaps a tornado over
the next few hours. Still, convection within this confluence zone is
separated from stronger deep-layer ascent, and given the relatively
poor lapse rate environment, the severe threat is expected to remain
relatively sparse in the short term.
A WW issuance is uncertain in the near term, though a WW issuance is
likely in association with the development of upstream convection
across the western Carolinas, when deep-layer ascent has increased.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 33137918 33547953 34947926 35507888 35867807 35857750
35757732 35517719 34357777 33467875 33137918