Day 1 Severe Weather Outlook

Valid 132000Z – 141200Z


Showers and isolated thunderstorms may continue to enhance potential
for isolated damaging wind gusts across parts of the south Atlantic
coastal plain late this afternoon.

…20Z Outlook Update…
Mid-level ridging, centered over the western subtropical Atlantic,
is maintaining considerable influence across much of the southern
Atlantic Coast states. While a gradual west to east erosion of
this ridge is ongoing, as a surface cold front approaches the
southern Atlantic coastal plain, this appears largely in response to
subtle perturbations migrating around its northwestern periphery. A
more general transition to cyclonic mid-level flow does not appear
likely until later tonight, in response to the gradual approach of
increasingly sheared larger-scale troughing within the mid-latitude

Lightning production with frontal/post-frontal convection has
generally been limited in areal coverage, and probably confined to
areas of locally enhanced mid/upper forcing for ascent, with warm
and dry mid-level air associated with the subtropical ridge
otherwise inhibiting thunderstorm development.

Still, weak boundary layer destabilization and lift along the
shallow surface front has been sufficient to maintain a narrow line
of low-topped convection, which will overspread the remainder of the
Carolina and Georgia coastal plain by 14/00-02Z. Although the
50-70 kt southwesterly 850 mb jet core has largely shifted
northeast of the southern Mid Atlantic coast, mean lower/mid
tropospheric wind fields across the southern Atlantic coastal plain
generally remain in excess of 40 kt. And enhanced downward mixing of
higher momentum within the narrow convective line may still be
capable of producing occasional, sporadic potentially damaging wind
gusts before it advances offshore.

..Kerr.. 02/13/2020

.PREV DISCUSSION… /ISSUED 1023 AM CST Thu Feb 13 2020/

…Southeast Atlantic states this afternoon…
A positive-tilt midlevel trough and associated confluent flow regime
aloft will support expansion of a surface ridge across the MS/OH
Valleys, as a cold front progresses across the Southeast states. A
narrow convective band, with occasional embedded thunderstorms,
accompanies the cold front from the FL Panhandle to the Piedmont of
the Carolinas. Surface heating in cloud breaks in advance of the
front, where boundary-layer dewpoints will remain in the mid-upper
60s through the afternoon, will contribute to some destabilization.
The convective band will likely be maintained through the afternoon,
though substantial intensification is not expected as a result of
poor midlevel lapse rates associated with the persistent midlevel
ridge near the Bahamas. Otherwise, low-midlevel flow and vertical
shear will remain sufficiently strong to support a threat for
isolated damaging gusts this afternoon with the stronger embedded
cells/bowing segments, prior to the convective band reaching the
Atlantic coast from GA to NC by late afternoon/evening.


Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.