Alert archive / Georgia / Flash Flood Warnings in 2020

Flash Flood Warning 28, NWS Atlanta, GA

July 18, 20204 counties in Georgia

NWS Atlanta, GA issued this flash flood warning at Jul 18, 2020, 6:19 PM EDT for 4 counties in Georgia. It was in force for 4 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: Jul 18, 2020, 6:19 PM EDT (22:19 UTC)
Expired: Jul 18, 2020, 9:53 PM EDT
In force: 4 hr
Issued by: NWS Atlanta, GA
Area: Storm-based polygon
Flood severity: None

Counties Barrow County, GA, Gwinnett County, GA, Hall County, GA, Jackson County, GA

The radar

The Atlanta radar (KFFC), 106 km from the middle of the area, began a volume at 22:21 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.

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 10.3 hours before the alert went out and 102 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: 462 J/kg
Mixed-layer CIN: -60 J/kg
Mixed-layer LCL: 1289 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -3 m²/s²
0-3 km storm-relative helicity: 22 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

659 
WGUS52 KFFC 182219
FFWFFC
GAC013-135-139-157-190415-
/O.NEW.KFFC.FF.W.0028.200718T2219Z-200719T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Peachtree City GA
619 PM EDT Sat Jul 18 2020

The National Weather Service in Peachtree City has issued a

* Flash Flood Warning for...
  Northwestern Barrow County in north central Georgia...
  Northeastern Gwinnett County in north central Georgia...
  South Central Hall County in north central Georgia...
  West Central Jackson County in northeastern Georgia...

* Until 1215 AM EDT.

* At 619 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1.5 and 3 inches of 
  rain have fallen. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Doppler radar.

  IMPACT...Flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other
           drainage and low lying areas.

* Some locations that will experience flash flooding include...
  Winder, Buford, Braselton, Auburn, Flowery Branch, Hoschton, Carl, 
  Rest Haven, Chateau Elan, Thompsons Mill, Road Atlanta-Lanier 
  Speedway, Chestnut Mountain, County Line and Hog Mountain.

Additional rainfall amounts of 1/2 to 1 inch is possible across 
eastern Gwinnett, Western Barrow Western Jackson, and Southern Hall 
counties over the next hour.

LAT...LON 3415 8396 3417 8392 3419 8389 3419 8374
      3408 8368 3398 8377 3407 8403

FLASH FLOOD...RADAR INDICATED
EXPECTED RAINFALL...0.5-1 INCH IN 1 HOUR 

$$

1 follow-up statement

167 
WGUS72 KFFC 190153
FFSFFC

Flash Flood Statement
National Weather Service Peachtree City GA
953 PM EDT Sat Jul 18 2020

GAC013-135-139-157-190203-
/O.CAN.KFFC.FF.W.0028.000000T0000Z-200719T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Barrow GA-Gwinnett GA-Hall GA-Jackson GA-
953 PM EDT Sat Jul 18 2020

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHWESTERN BARROW, 
NORTHEASTERN GWINNETT, SOUTH CENTRAL HALL AND WEST CENTRAL JACKSON 
COUNTIES...

Flood waters have receded. The heavy rain has ended. Flooding is no 
longer expected to pose a threat. Please continue to heed any 
existing road closures.

LAT...LON 3415 8396 3417 8392 3419 8389 3419 8374
      3408 8368 3398 8377 3407 8403

$$

DJN

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 18, 1:59 PM EDT	Special Weather Statement	FFC	Wilkes	31 min
Jul 18, 2:22 PM EDT	Special Weather Statement	FFC	Floyd	23 min
Jul 18, 2:30 PM EDT	Special Weather Statement	FFC	Walker	30 min
Jul 18, 3:45 PM EDT	Special Weather Statement	FFC	Gordon	30 min
Jul 18, 4:26 PM EDT	Special Weather Statement	FFC	Paulding, Polk	34 min
Jul 18, 4:41 PM EDT	Severe Thunderstorm Warning	FFC	Paulding	34 min
Jul 18, 4:51 PM EDT	Special Weather Statement	FFC	Fulton	24 min
Jul 18, 5:01 PM EDT	Special Weather Statement	FFC	Douglas	29 min
Jul 18, 5:08 PM EDT	Severe Thunderstorm Warning	FFC	Cobb, Douglas, Fulton, Paulding	41 min
Jul 18, 5:11 PM EDT	Special Weather Statement	FFC	Gwinnett	34 min
Jul 18, 5:36 PM EDT	Severe Thunderstorm Warning	FFC	Cobb, DeKalb, Fulton, Gwinnett	39 min
Jul 18, 5:37 PM EDT	Special Weather Statement	FFC	Barrow	23 min
Jul 18, 6:08 PM EDT	Special Weather Statement	FFC	Barrow	37 min
Jul 18, 6:17 PM EDT	Special Weather Statement	FFC	Newton	28 min
Jul 18, 6:34 PM EDT	Special Weather Statement	FFC	Newton	26 min
Jul 18, 6:46 PM EDT	Special Weather Statement	FFC	Coweta	29 min
Jul 18, 7:00 PM EDT	Special Weather Statement	FFC	Newton	30 min
Jul 18, 7:14 PM EDT	Special Weather Statement	FFC	Heard	31 min
Jul 18, 7:17 PM EDT	Special Weather Statement	FFC	Henry	28 min
Jul 18, 7:35 PM EDT	Special Weather Statement	FFC	Putnam	25 min

Nearby

Flash Flood Warnings in Georgia, 2020 Every flash flood warning in 2020

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.