Alert archive / South Carolina / Tornado Watches in 2012
Tornado Watch 685
The Storm Prediction Center issued this tornado watch at Dec 17, 2012, 2:55 PM EST for 7 counties in South Carolina. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 17, 2012, 2:55 PM EST (19:55 UTC)
- Expired
- Dec 17, 2012, 5:20 PM EST
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
Counties Beaufort County, SC, Berkeley County, SC, Charleston County, SC, Colleton County, SC, Dorchester County, SC, Hampton County, SC, Jasper County, SC
The radar
The Charleston,SC radar (KCLX), 61 km from the middle of the area, began a volume at 19:55 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
- 30%
- One or more EF2 to EF5 tornadoes
- 10%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 5%
- 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
- 50%
Warnings issued inside it
3 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 17, 3:47 PM EST | Severe Thunderstorm Warning | CHS | Beaufort, Jasper | 34 min |
| Dec 17, 3:57 PM EST | Severe Thunderstorm Warning | CHS | Beaufort, Charleston, Colleton, Jasper | 63 min |
| Dec 17, 4:42 PM EST | Severe Thunderstorm Warning | CHS | Berkeley, Charleston | 52 min |
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, 7.9 hours before the alert went out and 49 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 562 m above ground
- 0-6 km bulk shear
- 64 kt
- 0-1 km storm-relative helicity
- 79 m²/s²
- 0-3 km storm-relative helicity
- 168 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
657
WWUS20 KWNS 171955
SEL5
SPC WW 171955
SCZ000-CWZ000-180200-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 685
NWS STORM PREDICTION CENTER NORMAN OK
255 PM EST MON DEC 17 2012
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
SOUTHERN AND EASTERN SOUTH CAROLINA
COASTAL WATERS
EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 255 PM UNTIL 900
PM EST.
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 40 STATUTE
MILES EITHER SIDE OF A LINE FROM 80 MILES SOUTHWEST OF CHARLESTON
SOUTH CAROLINA TO 45 MILES EAST NORTHEAST OF CHARLESTON SOUTH
CAROLINA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU5).
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 683...WW 684...
DISCUSSION...SW-NE SQLN OVER SRN/ERN GA...WITH EMBEDDED LEWPS/BOWING
SEGMENTS...EXPECTED TO CONTINUE E INTO SRN/ERN SC...WHERE LOW-LVL
AIR MASS RECOVERY CONTINUES INVOF DIFFUSE W-E WARM FRONT. STRENGTH
OF LOW TO MID-LVL WIND FIELD AND PRESENCE OF SUSTAINED
STORMS/EMBEDDED SUPERCELLS UPSTREAM WITHIN SQLN...SUGGEST POTENTIAL
FOR DMGG WIND AND POSSIBLY A TORNADO OR TWO...THROUGH EARLY EVE.
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
350. MEAN STORM MOTION VECTOR 26045.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 17, 2:28 PM EST | Mesoscale Discussion | SPC | Allendale, Beaufort, Berkeley, Charleston, Colleton, Dorchester and 3 more | 92 min |
Nearby
Tornado Watches in South Carolina, 2012Every tornado watch in 2012
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.