Alert archive / South Carolina / Dense Fog Advisories in 2021

Dense Fog Advisory 20, NWS Columbia, SC

December 17, 202118 counties in South Carolina; 5 counties in Georgia

NWS Columbia, SC issued this dense fog advisory at Dec 17, 2021, 9:36 PM EST for 18 counties in South Carolina; 5 counties in Georgia. It was in force for 12 hr.

The area

The counties it named.

The facts

Issued: Dec 17, 2021, 9:36 PM EST (02:36 UTC)
Expired: Dec 18, 2021, 9:30 AM EST
In force: 12 hr
Issued by: NWS Columbia, SC

All 23 counties

Burke County, GA, Columbia County, GA, Lincoln County, GA, McDuffie County, GA, Richmond County, GA, Aiken County, SC, Bamberg County, SC, Barnwell County, SC, Calhoun County, SC, Chesterfield County, SC, Clarendon County, SC, Edgefield County, SC, Fairfield County, SC, Kershaw County, SC, Lancaster County, SC, Lee County, SC, Lexington County, SC, McCormick County, SC, Newberry County, SC, Orangeburg County, SC, Richland County, SC, Saluda County, SC, Sumter County, SC

The radar

The Columbia radar (KCAE), 22 km from the middle of the area, began a volume at 02:36 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 00:00Z, 2.6 hours before the alert went out and 160 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: 113 J/kg
Mixed-layer CIN: -5 J/kg
Mixed-layer LCL: 678 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 21 m²/s²
0-3 km storm-relative helicity: 80 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this dense fog advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Columbia, SC wrote its last area forecast discussion before this dense fog advisory went out at Dec 17, 6:35 PM EST, 3 hours 1 minute earlier.

Area forecast discussion, Dec 17, 6:35 PM EST, 3 hours 1 minute before

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Hazardous weather outlook, Dec 17, 10:15 AM EST, 11 hours 21 minutes before

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The office that day

Everything else NWS Columbia, SC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Dec 18, 5:07 PM EST	Special Weather Statement	CAE	McCormick	23 min
Dec 18, 5:42 PM EST	Special Weather Statement	CAE	Edgefield	48 min
Dec 18, 6:30 PM EST	Special Weather Statement	CAE	Aiken, Lexington	45 min

Nearby

Dense Fog Advisories in South Carolina, 2021 Dense Fog Advisories in Georgia, 2021 Every dense fog advisory 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.