Alert archive / Georgia / Flash Flood Warnings in 2020

Flash Flood Warning 67, NWS Atlanta, GA

October 24, 20205 counties in Georgia

NWS Atlanta, GA issued this flash flood warning at Oct 24, 2020, 7:32 PM EDT for 5 counties in Georgia. It was in force for 6 hr. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Oct 24, 2020, 7:32 PM EDT (23:32 UTC)
Expired
Oct 25, 2020, 1:30 AM EDT
In force
6 hr
Issued by
NWS Atlanta, GA
Area
Storm-based polygon
Flood severity
None

Counties Clayton County, GA, Cobb County, GA, DeKalb County, GA, Fulton County, GA, Gwinnett County, GA

The radar

The Atlanta radar (KFFC), 59 km from the middle of the area, began a volume at 23:30 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 was reported inside it

TimeReportWhereRemark
Oct 24, 7:55 PM EDTFLASH FLOOD2 Ssw Bankhead, GAWATER RESCUE OF 2 VECHICLES ON VERBENA ST.
Oct 24, 7:55 PM EDTFLASH FLOOD3 Nw Cascade Heights, GAWATER REPORTED INSIDE 3 BUILDINGS.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 11.5 hours before the alert went out and 57 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 2020-10-24Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 214 joules per kilogram.LCLLFCEL10008507005003002001001 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 2020-10-24The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 22 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
214 J/kg
Mixed-layer CIN
-51 J/kg
Mixed-layer LCL
780 m above ground
0-6 km bulk shear
15 kt
0-1 km storm-relative helicity
22 m²/s²
0-3 km storm-relative helicity
21 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

068 
WGUS52 KFFC 242332
FFWFFC
GAC063-067-089-121-135-250530-
/O.NEW.KFFC.FF.W.0067.201024T2332Z-201025T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Peachtree City GA
732 PM EDT Sat Oct 24 2020

The National Weather Service in Peachtree City has issued a

* Flash Flood Warning for...
  Northwestern Clayton County in north central Georgia...
  Eastern Cobb County in north central Georgia...
  DeKalb County in north central Georgia...
  Central Fulton County in north central Georgia...
  Southwestern Gwinnett County in north central Georgia...

* Until 130 AM EDT.

* At 732 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 3 inches of rain 
  have fallen. Flash flooding is already occurring.

  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...
  Atlanta, Marietta, Decatur, Sandy Springs, Roswell, Johns Creek, 
  Alpharetta, Smyrna, Dunwoody, East Point, Duluth, Forest Park, 
  College Park, Lilburn, Chamblee, Norcross, Doraville, Clarkston, 
  Hapeville and Stone Mountain.

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.

&&

LAT...LON 3379 8459 3407 8442 3407 8416 3404 8412
      3365 8415 3364 8445

FLASH FLOOD...RADAR INDICATED

$$
1 follow-up statement
891 
WGUS72 KFFC 250005
FFSFFC

Flash Flood Statement
National Weather Service Peachtree City GA
805 PM EDT Sat Oct 24 2020

GAC063-067-089-121-135-250530-
/O.CON.KFFC.FF.W.0067.000000T0000Z-201025T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Clayton GA-Cobb GA-DeKalb GA-Fulton GA-Gwinnett GA-
805 PM EDT Sat Oct 24 2020

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 130 AM EDT SUNDAY FOR 
NORTHWESTERN CLAYTON, EASTERN COBB, DEKALB, CENTRAL FULTON AND 
SOUTHWESTERN GWINNETT COUNTIES...

At 805 PM EDT, emergency management reported thunderstorms producing 
heavy rain across the warned area. Between 1 and 3.5 inches of rain 
have fallen. Flash flooding is already occurring. Emergency 
management has reported water rescues and flooded roadways within 
the warned area.

HAZARD...Life threatening flash flooding. Thunderstorms producing
         flash flooding.

SOURCE...Emergency management.

IMPACT...Life threatening flash flooding of creeks and streams,
         urban areas, highways, streets and underpasses.

Some locations that will experience flash flooding include...
  Atlanta, Marietta, Decatur, Sandy Springs, Roswell, Johns Creek, 
  Alpharetta, Smyrna, Dunwoody, East Point, Duluth, Forest Park, 
  College Park, Lilburn, Chamblee, Norcross, Doraville, Clarkston, 
  Hapeville and Stone Mountain.

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.

&&

LAT...LON 3379 8459 3407 8442 3407 8416 3404 8412
      3365 8415 3364 8445

FLASH FLOOD...OBSERVED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 24, 4:45 PM EDTSpecial Weather StatementFFCChattahoochee, Harris, Marion, Muscogee, Stewart, Talbot and 1 more30 min
Oct 24, 6:23 PM EDTSpecial Weather StatementFFCBanks, Jackson22 min
Oct 24, 6:28 PM EDTSpecial Weather StatementFFCClayton, Cobb, DeKalb, Fulton32 min
Oct 24, 6:53 PM EDTSpecial Weather StatementFFCBanks37 min
Oct 24, 7:22 PM EDTRiver Flood WarningFFCDeKalb4 hr

Nearby

Flash Flood Warnings in Georgia, 2020Every 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.