Mesoscale Discussion 552

Issued

Apr 23, 2017, 10:32 PM EDT (02:32 UTC)

Expired

Apr 24, 2017, 1:00 AM EDT

In force

2 hr

Issued by

the Storm Prediction Center

Chance of a watch

20%

Counties Bryan County, GA, Chatham County, GA, Effingham County, GA, Screven County, GA, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Beaufort County, SC, Berkeley County, SC, Calhoun County, SC, Charleston County, SC, Clarendon County, SC, Colleton County, SC, Dorchester County, SC, Georgetown County, SC, Hampton County, SC, Jasper County, SC, Orangeburg County, SC, Sumter County, SC, Williamsburg County, SC

The Charleston,SC radar (KCLX), 48 km from the middle of the area, began a volume at 02:33 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.

440 
ACUS11 KWNS 240232
SWOMCD
SPC MCD 240232 
SCZ000-GAZ000-240500-

Mesoscale Discussion 0552
NWS Storm Prediction Center Norman OK
0932 PM CDT Sun Apr 23 2017

Areas affected...Southeast GA...Central/Eastern SC

Concerning...Severe potential...Watch unlikely 

Valid 240232Z - 240500Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorms are expected to persist into late tonight,
especially across portions of South Carolina. The strongest cells
will be capable of locally damaging wind and perhaps a tornado or
two. Watch issuance is considered unlikely at this time.

DISCUSSION...Thunderstorms have recently increased in coverage and
intensity across portions of eastern GA into west-central SC. This
increase occurred in conjunction with a collision of the
westward-moving sea breeze and an eastward-moving outflow boundary
emanating from earlier convection over GA. The resulting composite
boundary extends southward from a weak surface low over eastern GA,
with another nearly-stationary boundary extending eastward from the
low across central SC. 

A few cells have exhibited weak rotation across portions of
west-central SC in Aiken and Barnwell counties, though these are
likely slightly elevated and up to now have not appeared to pose an
appreciable severe risk. Cells further south have shown less
organization, but as they advance eastward into a somewhat more
unstable airmass across the coastal plain of SC, some increase in
intensity is possible with a risk of locally damaging wind in the
short term. 

Later this evening, a modest increase in the low-level jet is
anticipated in response to a well-defined upper low that will move
slowly east-southeastward into GA. As this occurs, cells that are
able to interact with the frontal boundary (which may move slowly
northward as a warm front with time) may pose a threat of a brief
tornado or two, though widespread convection and relatively weak
deep-layer shear will likely keep the severe threat relatively
limited. While a low-end severe threat will exist for much of the
night, the magnitude of the threat at any particular location and
time is currently expected to remain too limited for watch issuance.

..Dean/Guyer.. 04/24/2017

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

ATTN...WFO...ILM...CHS...CAE...

LAT...LON   32718163 33238157 33728142 34058052 33997956 33827892
            33227913 32787973 32368044 31878113 31948167 32278171
            32718163

Mesoscale Discussions in South Carolina, 2017Mesoscale Discussions in Georgia, 2017Every mesoscale discussion in 2017

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.