Mesoscale Discussion 421

Issued

Apr 24, 2021, 10:10 AM EDT (14:10 UTC)

Expired

Apr 24, 2021, 11:45 AM EDT

In force

95 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch likely

Chance of a watch

80%

The Jacksonville radar (KJAX), 112 km from the middle of the area, began a volume at 14:11 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

• Tornado Watch 107Apr 24, 10:35 AM EDT

291 
ACUS11 KWNS 241410
SWOMCD
SPC MCD 241410 
SCZ000-GAZ000-FLZ000-241545-

Mesoscale Discussion 0421
NWS Storm Prediction Center Norman OK
0910 AM CDT Sat Apr 24 2021

Areas affected...southeast Georgia and far southern South Carolina

Concerning...Severe potential...Watch likely 

Valid 241410Z - 241545Z

Probability of Watch Issuance...80 percent

SUMMARY...Well established squall line with embedded areas of
rotation persists this morning across southern Georgia and northern
Florida. A new watch will likely be needed downstream of Tornado
Watch #106.

DISCUSSION...A well established quasi-linear convective system, with
embedded meso-vortices, continues moving east across southern
Georgia this morning. The airmass feeding these storms is best
characterized by mixed-layer CAPE on the order of 500 J/kg and
deep-layer shear around 70 knots. This is sufficient to maintain
QLCS organization for the next few hours as storms continue across
Tornado Watch #106. The forward speed of this complex will result in
thunderstorms exiting existing watches later this morning. The
airmass downstream of ongoing watches is drier than farther west as
low-level trajectories have slowed the return of better/richer
moisture. A consequence of this is that thunderstorms will quickly
outpace the return of the stronger instability. Despite this weaker
instability, the well established nature of the thunderstorm complex
combined with the strong deep-layer shear should compensate somewhat
for the lack of better instability and a severe threat should
persist across southeast Georgia through the morning hours. 

A new watch will likely be issued soon for portions of southeast
Georgia and far southern South Carolina.

..Marsh/Hart.. 04/24/2021

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

ATTN...WFO...CHS...JAX...FFC...TAE...

LAT...LON   31868333 32308240 32258127 32208067 31858054 31168090
            30708127 30578192 30638266 30708334 31868333

Mesoscale Discussions in Georgia, 2021Mesoscale Discussions in Florida, 2021Every mesoscale discussion in 2021

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.