Alert archive / South Carolina / Mesoscale Discussions in 2021
Mesoscale Discussion 983
The Storm Prediction Center issued this mesoscale discussion at Jun 16, 2021, 1:52 PM EDT for Chatham County, Effingham County, Georgia; 6 counties in South Carolina. It was in force for 113 min.
The area
The outline as issued.
The facts
- Issued
- Jun 16, 2021, 1:52 PM EDT (17:52 UTC)
- Expired
- Jun 16, 2021, 3:45 PM EDT
- In force
- 113 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch unlikely
- Chance of a watch
- 5%
Counties Chatham County, GA, Effingham County, GA, Beaufort County, SC, Charleston County, SC, Colleton County, SC, Dorchester County, SC, Hampton County, SC, Jasper County, SC
The radar
The Charleston,SC radar (KCLX), 52 km from the middle of the area, began a volume at 17:52 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.
The nearest sounding before it
Charleston AFB, SC (KCHS), launched 12:00Z, 5.9 hours before the alert went out and 59 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 178 J/kg
- Mixed-layer CIN
- -155 J/kg
- Mixed-layer LCL
- 1295 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 0 m²/s²
- 0-3 km storm-relative helicity
- 104 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.2
The text
As transmitted.
946
ACUS11 KWNS 161753
SWOMCD
SPC MCD 161752
SCZ000-GAZ000-161945-
Mesoscale Discussion 0983
NWS Storm Prediction Center Norman OK
1252 PM CDT Wed Jun 16 2021
Areas affected...portions of southern South Carolina
Concerning...Severe potential...Watch unlikely
Valid 161752Z - 161945Z
Probability of Watch Issuance...5 percent
SUMMARY...A couple damaging gusts or perhaps a large hailstone may
occur with the stronger storms. Storm/severe coverage is expected to
be low, and a WW issuance is not expected.
DISCUSSION...Visible satellite depicts deepening CU along a
sea-breeze boundary which is beginning to merge with a southward
sagging cold front. In addition to strong surface heating, dewpoints
up to 70 F overspread by 8 C/km low-level lapse rates (per 17Z
mesoanalysis) are supporting up to 2000 J/kg MLCAPE. 40 kts of 500
mb westerly flow is overspreading the coastline ahead of the
mid-level trough axis, resulting in 40-50 kts of effective bulk
shear. Tropospheric winds are mainly unidirectional above 850 mb,
resulting in mainly straight hodographs based on 16Z RAP forecast
soundings, though the KCLX VWP shows slight surface-850 mb
curvature, likely do to some veering in proximity to the sea-breeze
boundary. As such, any storm that can initiate and become sustained
may acquire multicellular or perhaps transient supercellular
structure, with damaging gusts and perhaps a severe hailstone or two
the primary concerns.
Nonetheless, storm coverage is expected to be sparse, with storms
likely moving offshore within a couple hours after initiation. A WW
issuance is unlikely.
..Squitieri/Grams.. 06/16/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...CHS...
LAT...LON 31818095 32118129 32438139 32828113 33068088 33238034
33197981 33047935 32807952 32427996 32148043 31818095Nearby
Mesoscale Discussions in South Carolina, 2021Mesoscale Discussions in Georgia, 2021Every mesoscale discussion in 2021
Sources
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.