Alert archive / South Carolina / Flash Flood Watches in 2021

Flash Flood Watch 5, NWS Charleston, SC

August 22, 2021Berkeley County, Colleton County, Dorchester County, South Carolina

NWS Charleston, SC issued this flash flood watch at Aug 22, 2021, 3:07 PM EDT for Berkeley County, Colleton County, Dorchester County, South Carolina. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued
Aug 22, 2021, 3:07 PM EDT (19:07 UTC)
Expired
Aug 22, 2021, 7:39 PM EDT
In force
5 hr
Issued by
NWS Charleston, SC
Flood severity
None

Counties Berkeley County, SC, Colleton County, SC, Dorchester County, SC

The radar

The Charleston,SC radar (KCLX), 79 km from the middle of the area, began a volume at 19:06 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, 7.1 hours before the alert went out and 35 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-pSkew-T log-p diagram, Charleston AFB, SC at 12:00Z on 2021-08-22Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 890 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Charleston AFB, SC at 12:00Z on 2021-08-22The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 60 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
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
890 J/kg
Mixed-layer CIN
-34 J/kg
Mixed-layer LCL
704 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
60 m²/s²
0-3 km storm-relative helicity
92 m²/s²
Significant tornado parameter
0.1
Supercell composite
1.1

Open this sounding in Storm Lab

The text

As transmitted.

976 
WGUS62 KCHS 221907
FFACHS

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Charleston SC
307 PM EDT Sun Aug 22 2021

SCZ043>045-049-050-052-230200-
/O.NEW.KCHS.FF.A.0005.210822T1907Z-210823T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Inland Colleton-Dorchester-Inland Berkeley-Coastal Colleton-
Charleston-Tidal Berkeley-
Including the cities of Mount Pleasant, North Charleston, Edisto 
Beach, Saint George, Summerville, Moncks Corner, Walterboro, Daniel 
Island, Goose Creek, and Charleston
307 PM EDT Sun Aug 22 2021

...FLASH FLOOD WATCH IN EFFECT UNTIL 10 PM EDT THIS EVENING...

The National Weather Service in Charleston has issued a

* Flash Flood Watch for a portion of southeast South Carolina, 
  including the following areas, Charleston, Coastal Colleton, 
  Dorchester, Inland Berkeley, Inland Colleton and Tidal Berkeley.

* Until 10 PM EDT this evening.

* Widespread showers and thunderstorms with torrential rainfall will 
  impact much the Charleston Tri-County area and Colleton County 
  this evening. Rainfall amounts of 1 to 3 inches with localized 
  amounts in excess of 5 inches could fall, possibly in less than 2 
  hours. This combined with wet soils from recent heavy rains could 
  result in areas of flash flooding.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Be prepared to protect life and property, especially in areas prone 
to flooding. If flooding develops, move to higher ground 
immediately. If driving, be prepared for flooded roadways and 
possible road closures.

&&

$$
1 follow-up statement
855 
WGUS62 KCHS 222339
FFACHS

Flood Watch
National Weather Service Charleston SC
739 PM EDT Sun Aug 22 2021

SCZ043>045-049-050-052-230045-
/O.CAN.KCHS.FF.A.0005.000000T0000Z-210823T0200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Inland Colleton-Dorchester-Inland Berkeley-Coastal Colleton-
Charleston-Tidal Berkeley-
Including the cities of Mount Pleasant, North Charleston, Edisto 
Beach, Saint George, Summerville, Moncks Corner, Walterboro, Daniel 
Island, Goose Creek, and Charleston
739 PM EDT Sun Aug 22 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for a portion of southeast South Carolina, 
including the following areas, Charleston, Coastal Colleton, 
Dorchester, Inland Berkeley, Inland Colleton and Tidal Berkeley has 
been cancelled.

The Flood Watch is cancelled. Flash flooding is no longer expected 
to pose a threat.

$$

BSH

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 21, 9:46 PM EDTAreal Flood AdvisoryCHSAllendale, Hampton3 hr
Aug 22, 8:43 AM EDTSpecial Marine WarningCHS47 min
Aug 22, 1:41 PM EDTSpecial Marine WarningCHS94 min
Aug 22, 2:35 PM EDTSpecial Marine WarningCHS55 min
Aug 22, 4:50 PM EDTSpecial Marine WarningCHS115 min
Aug 22, 5:24 PM EDTSpecial Marine WarningCHS2 hr
Aug 22, 5:45 PM EDTSpecial Marine WarningCHS2 hr
Aug 22, 7:01 PM EDTSpecial Marine WarningCHS119 min
Aug 22, 7:32 PM EDTSpecial Marine WarningCHS118 min

Nearby

Flash Flood Watches in South Carolina, 2021Every flash flood watch 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.