Alert archive / South Carolina / Flash Flood Warnings in 2021

Flash Flood Warning 4, NWS Columbia, SC

August 17, 2021Lexington County, Richland County, South Carolina

NWS Columbia, SC issued this flash flood warning at Aug 17, 2021, 11:45 PM EDT for Lexington County, Richland County, South Carolina. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Aug 17, 2021, 11:45 PM EDT (03:45 UTC)
Expired: Aug 18, 2021, 1:45 AM EDT
In force: 2 hr
Issued by: NWS Columbia, SC
Area: Storm-based polygon
Flood severity: None

Counties Lexington County, SC, Richland County, SC

The radar

The Columbia radar (KCAE), 8 km from the middle of the area, began a volume at 03:43 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, 3.8 hours before the alert went out and 154 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: 1990 J/kg
Mixed-layer CIN: -1 J/kg
Mixed-layer LCL: 710 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 61 m²/s²
0-3 km storm-relative helicity: 71 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 2.0

Open this sounding in Storm Lab

The text

As transmitted.

589 
WGUS52 KCAE 180345
FFWCAE
SCC063-079-180545-
/O.NEW.KCAE.FF.W.0004.210818T0345Z-210818T0545Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Columbia SC
1145 PM EDT Tue Aug 17 2021

The National Weather Service in Columbia has issued a

* Flash Flood Warning for...
  East Central Lexington County in central South Carolina...
  Central Richland County in central South Carolina...

* Until 145 AM EDT.

* At 1145 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Up to 1 inch of rain has 
  fallen. Additional rainfall amounts up to 1 inch are possible in 
  the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Columbia, West Columbia, Cayce, Forest Acres, St. Andrews, Pine 
  Ridge, SC State Fair Grounds, West Columbia Riverwalk, Five 
  Points, Riverbanks Zoo, SC State Farmer's Market, Cayce Riverwalk, 
  Olympia, Guignard Park, Rosewood, Dixiana and Silver Lake.

This includes the following highways...
	Interstate 126 between mile markers 2 and 3.
	Interstate 77 between mile markers 0 and 5.
	Interstate 26 between mile markers 114 and 118.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Flash flooding will occur in the Five Points area extending 
downstream along Rocky Branch Creek. This includes Maxcy Gregg Park, 
areas of the USC campus along the creek, the intersection at Pickens 
and Blossom, the intersection at Whaley and Main and areas of the 
Olympia neighborhood along the creek.

Flooded roadways are nearly impossible to see at night. Avoid 
traveling in the warned area. Turn around, don't drown.

&&

LAT...LON 3401 8108 3404 8104 3406 8101 3405 8098
      3402 8097 3396 8099 3389 8102 3387 8110
      3391 8111 3396 8109

FLASH FLOOD...RADAR INDICATED

$$

CJR

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 17, 8:18 PM EDT	Special Weather Statement	CAE	Saluda	42 min
Aug 17, 8:22 PM EDT	Special Weather Statement	CAE	Aiken	53 min
Aug 17, 8:40 PM EDT	Severe Thunderstorm Warning	CAE	Aiken	50 min
Aug 17, 8:43 PM EDT	Tornado Warning	CAE	Lexington, Saluda	32 min
Aug 17, 9:18 PM EDT	Special Weather Statement	CAE	Fairfield, Lexington	42 min
Aug 17, 10:58 PM EDT	Areal Flood Advisory	CAE	Calhoun, Lexington, Richland	2 hr

Nearby

Flash Flood Warnings in South Carolina, 2021 Every flash flood warning 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.