Alert archive / Georgia / Tornado Watches in 2017

Tornado Watch 13

January 21, 201725 counties in Georgia; 14 counties in South Carolina

The Storm Prediction Center issued this tornado watch at Jan 21, 2017, 1:51 PM EST for 25 counties in Georgia; 14 counties in South Carolina. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jan 21, 2017, 1:51 PM EST (18:51 UTC)
Expired
Jan 21, 2017, 5:43 PM EST
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
65 kt
All 39 counties

Appling County, GA, Atkinson County, GA, Bacon County, GA, Bryan County, GA, Bulloch County, GA, Burke County, GA, Candler County, GA, Chatham County, GA, Clinch County, GA, Coffee County, GA, Columbia County, GA, Echols County, GA, Effingham County, GA, Evans County, GA, Jeff Davis County, GA, Jenkins County, GA, Liberty County, GA, Long County, GA, McDuffie County, GA, Pierce County, GA, Richmond County, GA, Screven County, GA, Tattnall County, GA, Ware County, GA, Wayne County, GA, Aiken County, SC, Allendale County, SC, Bamberg County, SC, Barnwell County, SC, Beaufort County, SC, Berkeley County, SC, Calhoun County, SC, Charleston County, SC, Colleton County, SC, Dorchester County, SC, Edgefield County, SC, Hampton County, SC, Jasper County, SC, Orangeburg County, SC

The radar

The Charleston,SC radar (KCLX), 84 km from the middle of the area, began a volume at 18:52 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
70%
One or more EF2 to EF5 tornadoes
30%
Ten or more severe wind reports
70%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
10%
Six or more combined severe hail and wind reports
90%

Warnings issued inside it

18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jan 21, 2:13 PM ESTTornado WarningCAEBurke21 min
Jan 21, 2:13 PM ESTSevere Thunderstorm WarningCHSBulloch, Candler, Evans, Jenkins, Screven, Tattnall62 min
Jan 21, 2:15 PM ESTSevere Thunderstorm WarningJAXAtkinson, Bacon, Coffee45 min
Jan 21, 2:21 PM ESTTornado WarningCHSJenkins, Screven24 min
Jan 21, 2:22 PM ESTSevere Thunderstorm WarningJAXAppling23 min
Jan 21, 2:23 PM ESTSevere Thunderstorm WarningCAEBurke, Richmond56 min
Jan 21, 2:32 PM ESTTornado WarningJAXAppling13 min
Jan 21, 2:44 PM ESTTornado WarningCHSLong, Tattnall31 min
Jan 21, 2:57 PM ESTSevere Thunderstorm WarningJAXAppling, Bacon, Coffee19 min
Jan 21, 2:58 PM ESTTornado WarningCHSScreven32 min
Jan 21, 3:06 PM ESTSevere Thunderstorm WarningCHSBryan, Bulloch, Effingham, Evans, Liberty, Long and 2 more54 min
Jan 21, 3:16 PM ESTTornado WarningCHSHampton, Jasper29 min
Jan 21, 3:38 PM ESTSevere Thunderstorm WarningCHSBryan, Chatham, Liberty67 min
Jan 21, 3:43 PM ESTSevere Thunderstorm WarningCAEBamberg, Barnwell, Orangeburg62 min
Jan 21, 3:50 PM ESTTornado WarningCAEBamberg, Barnwell, Orangeburg25 min
Jan 21, 3:56 PM ESTSevere Thunderstorm WarningCHSBeaufort, Berkeley, Charleston, Colleton, Dorchester, Jasper49 min
Jan 21, 4:15 PM ESTTornado WarningCAEOrangeburg17 min
Jan 21, 4:38 PM ESTSevere Thunderstorm WarningCAECalhoun, Clarendon, Orangeburg67 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, 6.9 hours before the alert went out and 184 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 2017-01-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 138 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 2017-01-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 22 square meters per square second.1939587897117Sfc1 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
138 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
581 m above ground
0-6 km bulk shear
25 kt
0-1 km storm-relative helicity
22 m²/s²
0-3 km storm-relative helicity
37 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

406 
WWUS20 KWNS 211850
SEL3  
SPC WW 211850
GAZ000-SCZ000-220000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 13
NWS Storm Prediction Center Norman OK
155 PM EST Sat Jan 21 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Eastern Georgia
  Southern South Carolina

* Effective this Saturday afternoon and evening from 155 PM until
  700 PM EST.

* Primary threats include...
  A few tornadoes likely with a couple intense tornadoes possible
  Scattered damaging winds likely with isolated significant gusts
    to 75 mph possible
  Isolated large hail events to 1.5 inches in diameter possible

SUMMARY...A fast-moving squall line over Georgia will track eastward
across the watch this afternoon.  Damaging winds and a few tornadoes
are expected along the leading edge of these storms.

The tornado watch area is approximately along and 60 statute miles
east and west of a line from 35 miles northwest of Orangeburg SC to
25 miles south of Waycross GA. For a complete depiction of the watch
see the associated watch outline update (WOUS64 KWNS WOU3).

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.

&&

OTHER WATCH INFORMATION...CONTINUE...WW 12...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 1.5 inches. Extreme turbulence and surface wind
gusts to 65 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 25040.

...Hart

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 21, 8:41 AM ESTMesoscale DiscussionSPCBaker, Baldwin, Ben Hill, Berrien, Bibb, Bleckley and 53 more94 min
Jan 21, 9:04 AM ESTTornado WatchSPCBaker, Baldwin, Ben Hill, Berrien, Bibb, Bleckley and 70 more6 hr
Jan 21, 10:19 AM ESTMesoscale DiscussionSPCBaker, Baldwin, Ben Hill, Bibb, Bleckley, Butts and 50 more86 min
Jan 21, 1:06 PM ESTMesoscale DiscussionSPCAppling, Atkinson, Bacon, Baker, Baldwin, Ben Hill and 73 more114 min
Jan 21, 2:12 PM ESTTornado WatchSPCBerrien, Brooks, Colquitt, Cook, Grady, Lanier and 2 more5 hr
Jan 21, 3:06 PM ESTMesoscale DiscussionSPCAppling, Atkinson, Bacon, Brantley, Bryan, Bulloch and 20 more84 min

Nearby

Tornado Watches in Georgia, 2017Tornado Watches in South Carolina, 2017Every tornado watch in 2017

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.