Alert archive / South Carolina / Tornado Watches in 2011
Tornado Watch 847
The Storm Prediction Center issued this tornado watch at Sep 6, 2011, 10:11 AM EDT for 5 counties in Georgia; 21 counties in South Carolina. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 6, 2011, 10:11 AM EDT (14:11 UTC)
- Expired
- Sep 6, 2011, 4:44 PM EDT
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 26 counties
Bryan County, GA, Chatham County, GA, Effingham County, GA, Liberty County, GA, Screven County, GA, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Beaufort County, SC, Berkeley County, SC, Calhoun County, SC, Charleston County, SC, Chesterfield County, SC, Clarendon County, SC, Colleton County, SC, Dorchester County, SC, Fairfield County, SC, Hampton County, SC, Jasper County, SC, Kershaw County, SC, Lancaster County, SC, Lee County, SC, Lexington County, SC, Orangeburg County, SC, Richland County, SC, Sumter County, SC
The radar
The Columbia radar (KCAE), 42 km from the middle of the area, began a volume at 14:14 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 70%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Charleston AFB, SC (KCHS), launched 12:00Z, 2.2 hours before the alert went out and 117 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.
- Mixed-layer CAPE
- 2469 J/kg
- Mixed-layer CIN
- -1 J/kg
- Mixed-layer LCL
- 646 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 172 m²/s²
- 0-3 km storm-relative helicity
- 163 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 6.3
The text
As transmitted, in the capitals the NWS used until 2016.
893
WWUS20 KWNS 061413
SEL7
SPC WW 061413
GAZ000-SCZ000-CWZ000-070000-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 847
NWS STORM PREDICTION CENTER NORMAN OK
1015 AM EDT TUE SEP 6 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
FAR EASTERN GEORGIA
CENTRAL AND EASTERN SOUTH CAROLINA
COASTAL WATERS
EFFECTIVE THIS TUESDAY MORNING AND EVENING FROM 1015 AM UNTIL 800
PM EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 35 STATUTE
MILES EAST AND WEST OF A LINE FROM 55 MILES NORTH NORTHEAST OF
COLUMBIA SOUTH CAROLINA TO 20 MILES EAST SOUTHEAST OF SAVANNAH
GEORGIA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 845...WW 846...
DISCUSSION...TSTMS SHOULD CONTINUE TO INCREASE IN COVERAGE AND
INTENSITY TODAY WITHIN MOIST LOW-LEVEL FLOW REGIME IN PLACE ACROSS
REGION. 12Z REGIONAL SOUNDINGS INDICATE THAT AIR MASS IS ALREADY
UNCAPPED AND FURTHER DAYTIME HEATING WILL YIELD MLCAPE VALUES
APPROACHING 1500-2500 J/KG. MOREOVER...AREA WILL REMAIN ALONG ERN
ENVELOPE OF STRONGER FLOW FIELD ATTENDANT TO SRN APPALACHIANS
CYCLONE WITH RESULTANT VERTICAL SHEAR SUPPORTIVE OF ORGANIZED STORM
MODES INCLUDING SUPERCELLS CAPABLE OF DAMAGING WINDS AND A COUPLE OF
TORNADOES.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 21030.
...MEADSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 5, 8:36 PM EDT | Mesoscale Discussion | SPC | Appling, Atkinson, Bacon, Baker, Ben Hill, Berrien and 52 more | 84 min |
| Sep 6, 4:36 AM EDT | Mesoscale Discussion | SPC | Chester, Chesterfield, Darlington, Dillon, Fairfield, Kershaw and 4 more | 84 min |
| Sep 6, 5:17 AM EDT | Tornado Watch | SPC | Chesterfield, Darlington, Dillon, Florence, Georgetown, Horry and 3 more | 9 hr |
| Sep 6, 8:35 AM EDT | Mesoscale Discussion | SPC | Chesterfield, Darlington, Dillon, Florence, Horry, Lancaster and 4 more | 85 min |
| Sep 6, 9:51 AM EDT | Tornado Watch | SPC | Cherokee, Chester, Spartanburg, Union, York | 6 hr |
| Sep 6, 12:41 PM EDT | Mesoscale Discussion | SPC | Darlington, Dillon, Florence, Georgetown, Horry, Marion and 2 more | 64 min |
| Sep 6, 1:32 PM EDT | Tornado Watch | SPC | Darlington, Dillon, Florence, Georgetown, Horry, Marion and 2 more | 7 hr |
| Sep 6, 4:41 PM EDT | Mesoscale Discussion | SPC | Chesterfield, Darlington, Dillon, Florence, Georgetown, Horry and 3 more | 64 min |
| Sep 6, 7:33 PM EDT | Mesoscale Discussion | SPC | Dillon, Florence, Georgetown, Horry, Marion | 117 min |
Nearby
Tornado Watches in South Carolina, 2011Tornado Watches in Georgia, 2011Every tornado watch in 2011
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.