Alert archive / Georgia / Flash Flood Warnings in 2017

Flash Flood Warning 14, NWS Atlanta, GA

April 23, 2017Gwinnett County, Georgia

NWS Atlanta, GA issued this flash flood warning at Apr 23, 2017, 5:30 PM EDT for Gwinnett County, 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: Apr 23, 2017, 5:30 PM EDT (21:30 UTC)
Expired: Apr 23, 2017, 9:30 PM EDT
In force: 4 hr
Issued by: NWS Atlanta, GA
Area: Storm-based polygon
Flood severity: None

County Gwinnett County, GA

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 9.5 hours before the alert went out and 80 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: 60 J/kg
Mixed-layer CIN: -75 J/kg
Mixed-layer LCL: 772 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 75 m²/s²
0-3 km storm-relative helicity: 117 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

647 
WGUS52 KFFC 232130
FFWFFC
GAC135-240130-
/O.NEW.KFFC.FF.W.0014.170423T2130Z-170424T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Peachtree City GA
530 PM EDT SUN APR 23 2017

The National Weather Service in Peachtree City has issued a

* Flash Flood Warning for...
  Gwinnett County in north central Georgia...

* Until 930 PM EDT

* At 529 PM EDT, Doppler radar indicated heavy rain across the 
  warned area. One to two inches of rain has already fallen within 
  the warned area. Flash flooding is expected to begin shortly with 
  Pew Creek in Lawrenceville expected to reach flood stage.

* Some locations that will experience flooding include...
  Lawrenceville, Dunwoody, Duluth, Sugar Hill, Snellville, Suwanee,
  Buford, Lilburn, Norcross, Braselton, Dacula, Grayson, Berkeley
  Lake, Rest Haven, Mountain Park, Harbin, Buford Dam-Lake Lanier
  Parks, Rosebud, Mechanicsville and Hog Mountain.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

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 3410 8387 3412 8382 3400 8387 3393 8380
      3375 8402 3378 8408 3385 8416 3392 8426
      3396 8428 3397 8426 3399 8426 3400 8423
      3399 8419 3403 8417 3403 8412 3405 8410
      3407 8412 3415 8408 3417 8406

$$

1 follow-up statement

430 
WGUS72 KFFC 240002
FFSFFC

Flash Flood Statement
National Weather Service Peachtree City GA
802 PM EDT SUN APR 23 2017

GAC135-240012-
/O.CAN.KFFC.FF.W.0014.000000T0000Z-170424T0130Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Gwinnett GA-
802 PM EDT SUN APR 23 2017

...THE FLASH FLOOD WARNING FOR GWINNETT COUNTY IS CANCELLED...

The heavy rain has ended. Flooding is no longer expected to pose a
threat. Please continue to heed any remaining road closures.

LAT...LON 3410 8387 3412 8382 3400 8387 3393 8380
      3375 8402 3378 8408 3385 8416 3392 8426
      3396 8428 3397 8426 3399 8426 3400 8423
      3399 8419 3403 8417 3403 8412 3405 8410
      3407 8412 3415 8408 3417 8406

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 22, 8:03 PM EDT	Special Weather Statement	FFC	Walker	27 min
Apr 23, 6:00 AM EDT	Special Weather Statement	FFC	Henry, Rockdale, Walton	45 min
Apr 23, 6:45 AM EDT	Special Weather Statement	FFC	Barrow, Clarke, Madison, Oconee, Rockdale, Walton	45 min
Apr 23, 11:31 AM EDT	River Flood Warning	FFC	Dade	30 hr
Apr 23, 2:29 PM EDT	Special Weather Statement	FFC	Morgan	31 min
Apr 23, 3:00 PM EDT	Special Weather Statement	FFC	Oconee	30 min
Apr 23, 4:04 PM EDT	Special Weather Statement	FFC	Rockdale, Walton	26 min
Apr 23, 4:15 PM EDT	Special Weather Statement	FFC	Jasper	30 min
Apr 23, 4:43 PM EDT	Special Weather Statement	FFC	Jasper	32 min
Apr 23, 4:45 PM EDT	Special Weather Statement	FFC	Macon	30 min
Apr 23, 5:07 PM EDT	Severe Thunderstorm Warning	FFC	Houston, Macon, Peach	23 min
Apr 23, 5:22 PM EDT	Special Weather Statement	FFC	Jones	23 min
Apr 23, 5:29 PM EDT	Severe Thunderstorm Warning	FFC	Bleckley, Houston, Peach, Twiggs	31 min
Apr 23, 5:48 PM EDT	Flash Flood Warning	FFC	Newton, Rockdale, Walton	4 hr
Apr 23, 5:59 PM EDT	Special Weather Statement	FFC	Twiggs	31 min
Apr 23, 6:14 PM EDT	Severe Thunderstorm Warning	FFC	Twiggs, Wilkinson	31 min

Nearby

Flash Flood Warnings in Georgia, 2017 Every flash flood warning in 2017

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.