Alert archive / Georgia / Flash Flood Warnings in 2020

Flash Flood Warning 48, NWS Atlanta, GA

August 30, 2020Fulton County, Georgia

NWS Atlanta, GA issued this flash flood warning at Aug 30, 2020, 8:56 PM EDT for Fulton 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: Aug 30, 2020, 8:56 PM EDT (00:56 UTC)
Expired: Aug 31, 2020, 3:00 AM EDT
In force: 6 hr
Issued by: NWS Atlanta, GA
Area: Storm-based polygon
Flood severity: None

County Fulton County, GA

The radar

The Atlanta radar (KFFC), 85 km from the middle of the area, began a volume at 00:59 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, 0.9 hours before the alert went out and 82 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: 317 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 776 m above ground
0-6 km bulk shear: 13 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 78 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

393 
WGUS52 KFFC 310056
FFWFFC
GAC121-310700-
/O.NEW.KFFC.FF.W.0048.200831T0056Z-200831T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Peachtree City GA
856 PM EDT Sun Aug 30 2020

The National Weather Service in Peachtree City has issued a

* Flash Flood Warning for...
  Eastern Fulton County in north central Georgia...

* Until 300 AM EDT Monday.

* At 856 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 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...
  Johns Creek, Alpharetta, Duluth and Suwanee.

Additional rainfall amounts of 1 to 2 inches are possible in the 
warned area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the 
dangers of flooding.

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.

Please report flooding to your local law enforcement agency when you 
can do so safely.

A Flash Flood Warning means that flooding is imminent or occurring. 
If you are in the warned area move to higher ground immediately. 
Residents living along streams and creeks should take immediate 
precautions to protect life and property.

&&

LAT...LON 3403 8417 3403 8420 3407 8421 3409 8420
      3408 8419 3407 8418 3407 8416 3406 8414
      3406 8413 3405 8412 3405 8410 3403 8412
      3403 8414 3403 8416

FLASH FLOOD...RADAR INDICATED

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 30, 8:16 PM EDT	Special Weather Statement	FFC	Clayton	59 min
Aug 30, 8:30 PM EDT	Special Weather Statement	FFC	Gwinnett	30 min
Aug 30, 8:38 PM EDT	Flash Flood Warning	FFC	Clayton, Fayette, Fulton	6 hr
Aug 30, 8:52 PM EDT	Flash Flood Warning	FFC	Forsyth, Gwinnett	6 hr
Aug 30, 9:36 PM EDT	River Flood Warning	FFC	Gwinnett	3 hr
Aug 30, 9:49 PM EDT	River Flood Warning	FFC	Gwinnett	9 hr
Aug 30, 9:54 PM EDT	Flash Flood Warning	FFC	Cherokee, Cobb, Fulton	6 hr
Aug 31, 2:35 AM EDT	Areal Flood Warning	FFC	Clayton	6 hr
Aug 31, 2:58 AM EDT	River Flood Warning	FFC	Gwinnett, Walton	3 hr
Aug 31, 4:14 PM EDT	River Flood Warning	FFC	Clayton, Fayette, Spalding	13 hr
Aug 31, 6:52 PM EDT	Special Weather Statement	FFC	Sumter	38 min
Aug 31, 7:30 PM EDT	Special Weather Statement	FFC	Catoosa, Whitfield	30 min
Aug 31, 7:35 PM EDT	Special Weather Statement	FFC	Sumter	25 min
Aug 31, 7:57 PM EDT	Special Weather Statement	FFC	Crawford	18 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.