Update from the SPC.
...SUMMARY...
Severe thunderstorms with considerable potential for producing
damaging wind gusts and a few tornadoes are likely across much of
the southern through mid Atlantic Coast region, particularly across
the Carolinas into southern/central Virginia this afternoon and
evening.
...Coastal Southeast to Mid-Atlantic States...
Few changes to ongoing Moderate/Enhanced Risk Outlook with the 13Z
update.
An upper-level trough, which features a cyclonically curved strong
polar jet within its base, is centered along the lower/middle
Mississippi River Valley and Middle Gulf Coast early this morning.
This upper trough will continue to gradually deepen over the
Tennessee Valley, with the aforementioned polar jet ejecting
northeastward, largely atop an east/northeastward-advancing cold
front. A significant deep-layer strengthening of southerly winds
above 1 km AGL will occur during the day, highlighted by as much as
90 kt/70 kt at 500 mb/700 mb, respectively, particularly across
Georgia into the Carolinas and southern Virginia.
Semi-continuous bands of convection/squall line are ongoing from
northern Florida into Georgia and the western Carolinas early this
morning as of 13Z. Pockets of considerable cloud cover precedes this
convection (and the cold front itself), which casts some uncertainty
regarding the overall degree of destabilization and timing of
general intensification, although steady low-level moistening and
robust deep-layer/low-level winds will be compensatory factors.
Guidance generally remains suggestive that an influx of boundary
layer moisture across the Carolina coastal plain into the Piedmont
may be accompanied by moderate boundary layer destabilization
(including CAPE up to 1500 J/kg).
The aforementioned bands of convection should gradually increase in
intensity across Georgia and the upstate Carolinas through late
morning/early afternoon, with a semi-broken linearly prevalent
convective mode expected. The strengthening deep-layer/low-level
winds will likely yield further upscale growth and acceleration of
convection across the Carolinas into southern Virginia through peak
heating. Severe convective gusts may become fairly widespread. While
damaging wind gusts appear to be the main threat with the
northeastward and eastward advancing line of storms, a few embedded
tornadoes may also be possible. Preceding the linearly prevalent
convection, other showers/thunderstorms coincident with the
warm/moist conveyor may also deepen and become increasingly rooted
within the destabilizing boundary layer this afternoon across the
Piedmont and coastal plain of the Carolinas into southern Virginia.
These storms could materialize in a more discrete convective mode,
at least initially conducive for supercells with some tornado risk
aside from damaging winds.
