Alert archive / Georgia / Flash Flood Warnings in 2012

Flash Flood Warning 22, NWS Atlanta, GA

October 1, 2012DeKalb County, Gwinnett County, Georgia

NWS Atlanta, GA issued this flash flood warning at Oct 1, 2012, 10:56 PM EDT for DeKalb County, Gwinnett County, Georgia. It was in force for 6 hr. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Oct 1, 2012, 10:56 PM EDT (02:56 UTC)
Expired
Oct 2, 2012, 4:45 AM EDT
In force
6 hr
Issued by
NWS Atlanta, GA
Area
Storm-based polygon
Flood severity
None

Counties DeKalb County, GA, Gwinnett County, GA

The radar

The Atlanta radar (KFFC), 83 km from the middle of the area, began a volume at 02:56 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 00:00Z, 2.9 hours before the alert went out and 78 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 2012-10-02Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 988 joules per kilogram.LCLEL10008507005003002001001 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 2012-10-02The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 263 square meters per square second.19395878Sfc1 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
988 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
481 m above ground
0-6 km bulk shear
60 kt
0-1 km storm-relative helicity
263 m²/s²
0-3 km storm-relative helicity
292 m²/s²
Significant tornado parameter
1.8
Supercell composite
6.7

Open this sounding in Storm Lab

The text

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

989 
WGUS52 KFFC 020256
FFWFFC
GAC089-135-020845-
/O.NEW.KFFC.FF.W.0022.121002T0256Z-121002T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1056 PM EDT MON OCT 1 2012

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  EASTERN DEKALB COUNTY IN NORTH CENTRAL GEORGIA
  GWINNETT COUNTY IN NORTH CENTRAL GEORGIA

* UNTIL 445 AM EDT

* AT 1046 PM EDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED 
FLASH FLOODING FROM A HEAVY RAIN OVER THE WARNED AREA. DOPPLER RADAR 
HAS INDICATED THAT 1 TO 2 INCHES HAVE FALLEN IN THE LAST HOUR. THIS 
BRINGS THREE HOUR RAINFALL TOTALS TO 2 TO 4 INCHES.  

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO SUWANEE...
  SUGAR HILL...LAWRENCEVILLE AND DACULA.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...URBAN AREAS...HIGHWAYS...STREETS AND UNDERPASSES
AS WELL AS OTHER DRAINAGE AREAS AND LOW LYING SPOTS.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

IF YOU SEE SIGNIFICANT FLOODING 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 3407 8385 3406 8384 3368 8411 3374 8422
      3389 8415 3399 8412 3412 8403

$$
1 follow-up statement
564 
WGUS72 KFFC 020846
FFSFFC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
446 AM EDT TUE OCT 2 2012

GAC089-135-020850-
/O.EXP.KFFC.FF.W.0022.000000T0000Z-121002T0845Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
DEKALB GA-GWINNETT GA-
446 AM EDT TUE OCT 2 2012

...THE FLASH FLOOD WARNING WILL EXPIRE AT 445 AM EDT FOR GWINNETT AND
EASTERN DEKALB COUNTIES...

THE WIDESPREAD FLASH FLOODING HAS ENDED...HOWEVER MINOR FLOODING 
CONTINUES ON A FEW OF THE RIVERS AND CREEKS IN GWINNETT COUNTY...
INCLUDING THE ALCOVY RIVER BETWEEN LAWRENCEVILLE AND WINDSOR AND THE 
SWEETWATER CREEK NEAR PLEASANT HILL. 

IF YOU SEE SIGNIFICANT FLOODING 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 3407 8385 3406 8384 3368 8411 3374 8422
      3389 8415 3399 8412 3412 8403

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 1, 9:23 PM EDTFlash Flood WarningFFCHall6 hr
Oct 1, 10:17 PM EDTFlash Flood WarningFFCMeriwether, Pike, Spalding, Upson3 hr
Oct 1, 10:45 PM EDTSpecial Weather StatementFFCDeKalb, Gwinnett60 min
Oct 1, 10:54 PM EDTSpecial Weather StatementFFCDade36 min
Oct 2, 1:18 AM EDTRiver Flood WarningFFCGwinnett3 hr
Oct 2, 1:18 AM EDTRiver Flood WarningFFCGwinnett6 hr
Oct 2, 2:49 AM EDTFlash Flood WarningFFCWhite5 hr
Oct 2, 4:10 AM EDTRiver Flood WarningFFCGwinnett, Walton6 hr
Oct 2, 6:41 AM EDTRiver Flood WarningFFCGwinnett18 hr
Oct 2, 11:26 AM EDTRiver Flood WarningFFCDeKalb, Rockdale8 hr

Nearby

Flash Flood Warnings in Georgia, 2012Every flash flood 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.