From Virginia to Georgia to the coast, the severe weather outbreak continues for Saturday. The Storm Prediction Center sheds some light on this.
Day 3 convective outlook
National Weather Service Storm Prediction Center Norman OK
0217 am CDT Thursday Apr 14 2011
Valid 161200z – 171200z
..there is a slight risk of severe thunderstorms across parts of the
mid-Atlantic…Carolinas and eastern Georgia…
..mid-Atlantic/Carolinas/se Georgia/northern Florida…
An upper-level trough will move into the Ohio and Tennessee valleys Saturday
as a middle-level jet noses into the Carolinas. A line of strong
thunderstorms may be ongoing Saturday morning across the southern
Appalachian Mountains on the western edge of the low-level jet. As surface temperatures
warm ahead of the line…intensification should occur from central Virginia
south-southwestward across ecntrl NC into eastern SC and southeast Georgia Saturday afternoon.
Forecast soundings at 21z Saturday along this corridor show MLCAPE
values of 1000 to 1500 j/kg with 50 to 55 knots of deep layer shear.
This combined with strong low-level shear should be sufficient for
rotating storms and bowing-line segments along the leading edge of
very focused large-scale ascent. 40 to 50 knots of flow just above the
surface could favor wind damage as the main threat if a solid line moves
eastward across the region. However…low-level shear will be quite
strong due to a well-developed low-level jet. This will make
tornadoes a possibility especially if the storms can remain discrete
or if there are breaks within the line for any length of time during
the afternoon. An enhanced wind damage threat or tornado threat
could exist but too much uncertainty exists to forecast an enhanced
threat area. The severe threat should end during the overnight
period as the line moves off the coast.
Further south across northern Florida…moderate instability should be in
place ahead of a cold front advancing southeastward across the region.
Although convection may develop along the boundary as surface temperatures warm
Saturday…limited large-scale ascent will keep the storms isolated.
If a storm or two can initiate…then a marginal wind damage or hail
threat could exist due to the instability and moderate deep layer
shear evident on forecast soundings.