Alert archive / South Carolina / Tornado Watches in 2016

Tornado Watch 495

October 7, 2016Bryan County, Chatham County, Effingham County, Georgia; 7 counties in South Carolina

The Storm Prediction Center issued this tornado watch at Oct 7, 2016, 3:17 PM EDT for Bryan County, Chatham County, Effingham County, Georgia; 7 counties in South Carolina. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued: Oct 7, 2016, 3:17 PM EDT (19:17 UTC)
Expired: Oct 8, 2016, 12:00 AM EDT
In force: 9 hr
Issued by: the Storm Prediction Center
Largest hail expected: 0.5 in
Strongest gust expected: 60 kt

Counties Bryan County, GA, Chatham County, GA, Effingham County, GA, 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), 59 km from the middle of the area, began a volume at 19:21 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: 20%
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: 40%

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
Oct 7, 3:40 PM EDT	Tornado Warning	CHS	Beaufort, Jasper	12 min
Oct 7, 5:48 PM EDT	Flash Flood Warning	CHS	Bryan, Chatham, Liberty, Long, McIntosh	17 hr
Oct 7, 7:53 PM EDT	Flash Flood Warning	CHS	Berkeley, Charleston, Colleton, Dorchester	14 hr

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, 7.3 hours before the alert went out and 94 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: 220 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 471 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: 253 m²/s²
0-3 km storm-relative helicity: 250 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

As transmitted.

651 
WWUS20 KWNS 071916
SEL5  
SPC WW 071916
GAZ000-SCZ000-CWZ000-080400-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 495
NWS STORM PREDICTION CENTER NORMAN OK
315 PM EDT FRI OCT 7 2016

THE NWS STORM PREDICTION CENTER HAS ISSUED A

* TORNADO WATCH FOR PORTIONS OF 
  SOUTHEAST GEORGIA
  SOUTH CAROLINA COASTAL PLAIN
  COASTAL WATERS

* EFFECTIVE THIS FRIDAY AFTERNOON FROM 315 PM UNTIL MIDNIGHT EDT.

* PRIMARY THREATS INCLUDE...
  A COUPLE TORNADOES POSSIBLE
  ISOLATED DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

SUMMARY...THUNDERSTORMS EMBEDDED IN FEEDER BANDS WRAPPING AROUND
HURRICANE MATTHEW WILL CONTINUE TO MOVE ONSHORE THIS AFTERNOON AND
EVENING...POSING SOME RISK OF AN ISOLATED TORNADO OR TWO.

THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 30 STATUTE
MILES EITHER SIDE OF A LINE FROM 45 MILES SOUTH OF SAVANNAH
GEORGIA TO 35 MILES NORTHEAST OF CHARLESTON SOUTH CAROLINA.  FOR
A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU5).

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

&&

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 09045.


...HART

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 7, 3:50 PM EDT	Mesoscale Discussion	SPC	Chatham, Liberty, McIntosh	55 min

Nearby

Tornado Watches in South Carolina, 2016 Tornado Watches in Georgia, 2016 Every tornado watch in 2016

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.