Alert archive / Georgia / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 121, NWS Atlanta, GA

May 20, 2012Forsyth County, Georgia

NWS Atlanta, GA issued this severe thunderstorm warning at May 20, 2012, 6:27 PM EDT for Forsyth County, Georgia. It was in force for 22 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
May 20, 2012, 6:27 PM EDT (22:27 UTC)
Expired
May 20, 2012, 6:49 PM EDT
In force
22 min
Issued by
NWS Atlanta, GA
Area
Storm-based polygon

County Forsyth County, GA

The radar

The Atlanta radar (KFFC), 99 km from the middle of the area, began a volume at 22:27 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.

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 10.5 hours before the alert went out and 97 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 12:00Z on 2012-05-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Peachtre/Fal Fld, GA at 12:00Z on 2012-05-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -29 square meters per square second.1939Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1433 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
-29 m²/s²
0-3 km storm-relative helicity
16 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

891 
WUUS52 KFFC 202227
SVRFFC
GAC117-202315-
/O.NEW.KFFC.SV.W.0121.120520T2227Z-120520T2315Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
627 PM EDT SUN MAY 20 2012

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  CENTRAL FORSYTH COUNTY IN NORTH CENTRAL GEORGIA

* UNTIL 715 PM EDT

* AT 623 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING QUARTER SIZED HAIL...AND
  DAMAGING WINDS UP TO 60 MPH.  THIS STORM WAS LOCATED NEAR
  CUMMING...MOVING SOUTH AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL OTHERWISE REMAIN OVER MAINLY RURAL
  AREAS OF THE INDICATED COUNTY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

IN ADDITION TO LARGE HAIL AND DAMAGING WINDS...CONTINUOUS CLOUD TO
GROUND LIGHTNING IS OCCURRING WITH THIS STORM. MOVE INDOORS
IMMEDIATELY! REMEMBER...IF YOU CAN HEAR THUNDER...YOU ARE CLOSE
ENOUGH TO BE STRUCK BY LIGHTNING.

IF YOU SEE WIND DAMAGE...HAIL OR FLOODING...WAIT UNTIL THE STORM HAS
PASSED...AND THEN CALL THE NATIONAL WEATHER SERVICE TOLL FREE AT 1 8
6 6 7 6 3 4 4 6 6. YOU CAN ALSO TWEET YOUR REPORT USING HASHTAG GAWX.

&&

LAT...LON 3410 8411 3410 8426 3429 8426 3429 8425
      3430 8410
TIME...MOT...LOC 2228Z 359DEG 15KT 3420 8421

$$
1 follow-up statement
546 
WWUS52 KFFC 202249
SVSFFC

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
649 PM EDT SUN MAY 20 2012

GAC117-202300-
/O.CAN.KFFC.SV.W.0121.000000T0000Z-120520T2315Z/
FORSYTH GA-
649 PM EDT SUN MAY 20 2012

...THE SEVERE THUNDERSTORM WARNING FOR CENTRAL FORSYTH COUNTY IS
CANCELLED...

THE SEVERE THUNDERSTORM WILL OTHERWISE REMAIN OVER MAINLY RURAL AREAS
OF THE INDICATED COUNTY.

IF YOU SEE WIND DAMAGE...HAIL OR FLOODING...WAIT UNTIL THE STORM HAS
PASSED...AND THEN CALL THE NATIONAL WEATHER SERVICE TOLL FREE AT 1 8
6 6 7 6 3 4 4 6 6. YOU CAN ALSO TWEET YOUR REPORT USING HASHTAG GAWX.

LAT...LON 3410 8411 3411 8426 3429 8426 3429 8425
      3430 8410
TIME...MOT...LOC 2250Z 359DEG 15KT 3411 8421

$$

The office that day

Everything else NWS Atlanta, GA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
May 19, 8:28 PM EDTSpecial Weather StatementFFCTowns, Union32 min
May 20, 3:55 PM EDTSpecial Weather StatementFFCWalker35 min
May 20, 5:02 PM EDTSpecial Weather StatementFFCForsyth, Gwinnett28 min
May 20, 5:31 PM EDTSpecial Weather StatementFFCForsyth29 min
May 20, 6:08 PM EDTSpecial Weather StatementFFCDeKalb, Fulton37 min
May 20, 6:09 PM EDTSpecial Weather StatementFFCLumpkin36 min
May 20, 6:46 PM EDTSpecial Weather StatementFFCDeKalb29 min
May 20, 7:00 PM EDTSevere Thunderstorm WarningFFCClayton, DeKalb, Fulton31 min
May 20, 7:28 PM EDTSpecial Weather StatementFFCUnion32 min
May 20, 7:36 PM EDTSpecial Weather StatementFFCClayton, Fayette24 min
May 20, 7:58 PM EDTSpecial Weather StatementFFCCoweta, Fayette32 min

Nearby

Severe Thunderstorm Warnings in Georgia, 2012Every severe thunderstorm warning 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.