Alert archive / Georgia / Tornado Watches in 2017

Tornado Watch 129

April 5, 20177 counties in Alabama; 33 counties in Georgia

The Storm Prediction Center issued this tornado watch at Apr 5, 2017, 8:58 PM CDT for 7 counties in Alabama; 33 counties in Georgia. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Apr 5, 2017, 8:58 PM CDT (01:58 UTC)
Expired
Apr 6, 2017, 12:20 AM CDT
In force
3 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 40 counties

Barbour County, AL, Bullock County, AL, Chambers County, AL, Lee County, AL, Macon County, AL, Pike County, AL, Russell County, AL, Bibb County, GA, Butts County, GA, Chattahoochee County, GA, Clayton County, GA, Coweta County, GA, Crawford County, GA, DeKalb County, GA, Fayette County, GA, Gwinnett County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Jasper County, GA, Jones County, GA, Lamar County, GA, Marion County, GA, Meriwether County, GA, Monroe County, GA, Morgan County, GA, Muscogee County, GA, Newton County, GA, Pike County, GA, Putnam County, GA, Quitman County, GA, Rockdale County, GA, Spalding County, GA, Stewart County, GA, Talbot County, GA, Taylor County, GA, Troup County, GA, Upson County, GA, Walton County, GA, Webster County, GA

The radar

The Atlanta radar (KFFC), 40 km from the middle of the area, began a volume at 02:00 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
50%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
One or more gusts of 65 knots or more
20%
Ten or more severe hail reports
30%
One or more hailstones of 2 inches or more
30%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 5, 9:14 PM CDTSevere Thunderstorm WarningFFCCarroll, Coweta, Douglas, Fayette, Fulton46 min
Apr 5, 9:38 PM CDTSevere Thunderstorm WarningBMXLee37 min
Apr 5, 9:40 PM CDTSevere Thunderstorm WarningFFCHarris, Meriwether, Troup50 min
Apr 5, 9:53 PM CDTSevere Thunderstorm WarningFFCHarris, Marion, Meriwether, Muscogee, Talbot52 min
Apr 5, 10:55 PM CDTSevere Thunderstorm WarningFFCGreene, Morgan, Newton, Oconee, Walton20 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

Peachtre/Fal Fld, GA (KFFC), launched 00:00Z, 2.0 hours before the alert went out and 41 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, Peachtre/Fal Fld, GA at 00:00Z on 2017-04-06Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 723 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Peachtre/Fal Fld, GA at 00:00Z on 2017-04-06The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 354 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
723 J/kg
Mixed-layer CIN
-120 J/kg
Mixed-layer LCL
594 m above ground
0-6 km bulk shear
93 kt
0-1 km storm-relative helicity
354 m²/s²
0-3 km storm-relative helicity
356 m²/s²
Significant tornado parameter
0.9
Supercell composite
9.8

Open this sounding in Storm Lab

The text

As transmitted.

060 
WWUS20 KWNS 060155
SEL9  
SPC WW 060155
ALZ000-GAZ000-060600-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 129
NWS Storm Prediction Center Norman OK
955 PM EDT Wed Apr 5 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Far eastern Alabama
  Western and central Georgia

* Effective this Wednesday night and Thursday morning from 955 PM
  until 200 AM EDT.

* Primary threats include...
  A few tornadoes possible
  Scattered damaging wind gusts to 70 mph possible
  Isolated very large hail events to 2 inches in diameter possible

SUMMARY...Storms should continue to increase near an
eastward-accelerating cold front as it moves from Alabama into
Georgia. Especially given that low-level shear will be increasing
this evening, a tornado or two will be possible aside from what
should be a more prevalent risk for damaging winds and some severe
hail.

The tornado watch area is approximately along and 45 statute miles
east and west of a line from 45 miles east northeast of Atlanta GA
to 30 miles east southeast of Troy AL. For a complete depiction of
the watch see the associated watch outline update (WOUS64 KWNS
WOU9).

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 127...

AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 24035.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 5, 10:15 PM CDTMesoscale DiscussionSPCCharlton, Echols2 hr
Apr 5, 10:34 PM CDTMesoscale DiscussionSPCElbert, Lincoln, Wilkes56 min
Apr 5, 10:50 PM CDTSevere Thunderstorm WatchSPCBaldwin, Bleckley, Burke, Clarke, Columbia, Elbert and 24 more6 hr
Apr 5, 11:15 PM CDTTornado WatchSPCBrantley, Camden, Charlton, Clinch, Echols, Glynn and 1 more6 hr
Apr 6, 1:54 AM CDTMesoscale DiscussionSPCBurke, Columbia, Dodge, Emanuel, Jefferson, Jenkins and 4 more96 min
Apr 6, 2:12 AM CDTMesoscale DiscussionSPCAppling, Atkinson, Bacon, Berrien, Brantley, Brooks and 12 more2 hr

Nearby

Tornado Watches in Georgia, 2017Tornado Watches in Alabama, 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.