Alert archive / South Carolina / Mesoscale Discussions in 2018

Mesoscale Discussion 840

June 23, 201810 counties in Georgia; 17 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Jun 23, 2018, 3:38 PM EDT for 10 counties in Georgia; 17 counties in South Carolina. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued: Jun 23, 2018, 3:38 PM EDT (19:38 UTC)
Expired: Jun 23, 2018, 4:45 PM EDT
In force: 67 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 27 counties

Bryan County, GA, Bulloch County, GA, Candler County, GA, Chatham County, GA, Effingham County, GA, Emanuel County, GA, Evans County, GA, Jenkins County, GA, Screven County, GA, Treutlen County, GA, Aiken County, SC, 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, Hampton County, SC, Jasper County, SC, Lexington County, SC, Orangeburg County, SC, Sumter County, SC, Williamsburg County, SC

The radar

The Charleston,SC radar (KCLX), 43 km from the middle of the area, began a volume at 19:40 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, 7.6 hours before the alert went out and 108 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 648 J/kg
Mixed-layer CIN: -71 J/kg
Mixed-layer LCL: 1068 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: 19 m²/s²
0-3 km storm-relative helicity: 41 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 23, 11:32 AM EDT	Mesoscale Discussion	SPC	Bartow, Catoosa, Chattooga, Dade, Floyd, Gordon and 3 more	88 min
Jun 23, 12:09 PM EDT	Severe Thunderstorm Watch	SPC	Bartow, Catoosa, Chattooga, Dade, Floyd, Gordon and 3 more	4 hr

Nearby

Mesoscale Discussions in South Carolina, 2018 Mesoscale Discussions in Georgia, 2018 Every mesoscale discussion in 2018

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.