Alert archive / Georgia / Flash Flood Warnings in 2020

Flash Flood Warning 34, NWS Atlanta, GA

August 13, 2020Oconee County, Walton County, Georgia

NWS Atlanta, GA issued this flash flood warning at Aug 13, 2020, 8:59 PM EDT for Oconee County, Walton County, Georgia. It was in force for 2 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 13, 2020, 8:59 PM EDT (00:59 UTC)
Expired
Aug 13, 2020, 11:00 PM EDT
In force
2 hr
Issued by
NWS Atlanta, GA
Area
Storm-based polygon
Flood severity
None

Counties Oconee County, GA, Walton County, GA

The radar

The Atlanta radar (KFFC), 110 km from the middle of the area, began a volume at 01:02 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, 1.0 hours before the alert went out and 105 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 2020-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1129 joules per kilogram.LCLEL10008507005003002001001 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 00:00Z on 2020-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 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
1129 J/kg
Mixed-layer CIN
-4 J/kg
Mixed-layer LCL
1535 m above ground
0-6 km bulk shear
7 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
41 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

364 
WGUS52 KFFC 140059
FFWFFC
GAC219-297-140700-
/O.NEW.KFFC.FF.W.0034.200814T0059Z-200814T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Peachtree City GA
859 PM EDT Thu Aug 13 2020

The National Weather Service in Peachtree City has issued a

* Flash Flood Warning for...
  Northeastern Walton County in north central Georgia...
  Northwestern Oconee County in northeastern Georgia...

* Until 300 AM EDT Friday.

* At 859 PM EDT, Radar rainfall estimates between 1 and 3 inches of 
  rain have fallen and thunderstorms are still occurring. 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...
  Bogart and Eastville.

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

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3390 8359 3391 8359 3393 8357 3394 8352
      3393 8351 3393 8349 3392 8347 3389 8344
      3386 8348 3383 8357 3382 8364 3384 8368
      3387 8365

FLASH FLOOD...RADAR INDICATED

$$
2 follow-up statements
142 
WGUS72 KFFC 140207
FFSFFC

Flash Flood Statement
National Weather Service Peachtree City GA
1007 PM EDT Thu Aug 13 2020

GAC219-297-140700-
/O.CON.KFFC.FF.W.0034.000000T0000Z-200814T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Oconee GA-Walton GA-
1007 PM EDT Thu Aug 13 2020

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 3 AM EDT FRIDAY FOR 
NORTHEASTERN WALTON AND NORTHWESTERN OCONEE COUNTIES...

At 1007 PM EDT, Radar and gage rainfall estimates between 1 and 3 
inches of rain have fallen in the warned area. The heavy rain has 
tapered off however creeks and rivers will continue to rise well 
after the rain has ended. Flash flooding is expected to begin or 
continue.

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...
  Bogart and Eastville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Excessive runoff from heavy rainfall will cause flooding of small 
creeks and streams, country roads, farmland, and other low lying 
spots.

If you see significant flooding call the National Weather Service 
toll free at 1 8 6 6 7 6 3 4 4 6 6 or tweet us your report at 
NWSATLANTA.

&&

LAT...LON 3390 8359 3391 8359 3393 8357 3394 8352
      3393 8351 3393 8349 3392 8347 3389 8344
      3386 8348 3383 8357 3384 8368 3387 8365

FLASH FLOOD...RADAR INDICATED

$$
278 
WGUS72 KFFC 140300
FFSFFC

Flash Flood Statement
National Weather Service Peachtree City GA
1100 PM EDT Thu Aug 13 2020

GAC219-297-140310-
/O.CAN.KFFC.FF.W.0034.000000T0000Z-200814T0700Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Oconee GA-Walton GA-
1100 PM EDT Thu Aug 13 2020

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHEASTERN WALTON AND 
NORTHWESTERN OCONEE COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose an 
immediate threat to life and property.

LAT...LON 3390 8359 3391 8359 3393 8357 3394 8352
      3393 8351 3393 8349 3392 8347 3389 8344
      3386 8348 3383 8357 3384 8368 3387 8365

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 13, 8:23 PM EDTSpecial Weather StatementFFCGwinnett22 min
Aug 13, 8:30 PM EDTSpecial Weather StatementFFCForsyth30 min
Aug 13, 8:47 PM EDTSpecial Weather StatementFFCBarrow28 min
Aug 13, 8:51 PM EDTSpecial Weather StatementFFCOconee24 min
Aug 13, 9:10 PM EDTSpecial Weather StatementFFCWilkinson35 min
Aug 13, 9:16 PM EDTSpecial Weather StatementFFCFulton29 min
Aug 13, 9:31 PM EDTSpecial Weather StatementFFCWashington29 min
Aug 13, 9:41 PM EDTSpecial Weather StatementFFCMorgan34 min
Aug 13, 11:04 PM EDTSpecial Weather StatementFFCJefferson26 min
Aug 13, 11:05 PM EDTSpecial Weather StatementFFCPike25 min
Aug 13, 11:22 PM EDTRiver Flood WarningFFCDeKalb2 hr
Aug 14, 3:09 PM EDTSpecial Weather StatementFFCTwiggs36 min

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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.