Alert archive / South Carolina / Flash Flood Watches in 2020

Flash Flood Watch 6, NWS Charleston, SC

November 12, 2020Berkeley County, Dorchester County, South Carolina

NWS Charleston, SC issued this flash flood watch at Nov 12, 2020, 4:25 AM EST for Berkeley County, Dorchester County, South Carolina. It took effect at Nov 12, 2020, 10:00 AM EST. It was in force for 10 hr.

The area

The counties it named.

The facts

Issued: Nov 12, 2020, 4:25 AM EST (09:25 UTC)
In effect from: Nov 12, 2020, 10:00 AM EST
Expired: Nov 12, 2020, 8:17 PM EST
In force: 10 hr
Issued by: NWS Charleston, SC
Flood severity: None

Counties Berkeley County, SC, Dorchester County, SC

The radar

The Charleston,SC radar (KCLX), 97 km from the middle of the area, began a volume at 09:24 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, 9.4 hours before the alert went out and 31 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: 737 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 642 m above ground
0-6 km bulk shear: 36 kt
0-1 km storm-relative helicity: 126 m²/s²
0-3 km storm-relative helicity: 133 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.4

Open this sounding in Storm Lab

The office that day

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

Issued	Product	Office	Counties	Lasted
Nov 11, 10:15 PM EST	Gale Watch	CHS		6 hr
Nov 12, 4:11 AM EST	Small Craft Advisory	CHS		35 hr
Nov 12, 4:11 AM EST	Tropical Storm Warning	CHS		22 hr
Nov 12, 2:01 PM EST	Areal Flood Advisory	CHS	Berkeley, Colleton, Dorchester	119 min
Nov 12, 3:38 PM EST	Areal Flood Advisory	CHS	Berkeley, Charleston, Dorchester	3 hr
Nov 12, 4:46 PM EST	Special Weather Statement	CHS	Berkeley	44 min
Nov 12, 4:54 PM EST	Areal Flood Advisory	CHS	Berkeley, Charleston	3 hr
Nov 12, 6:24 PM EST	Lake Wind Advisory	CHS	Berkeley	4 hr

Nearby

Flash Flood Watches in South Carolina, 2020 Every flash flood watch in 2020

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.