Alert archive / Georgia / Flash Flood Warnings in 2011

Flash Flood Warning 5, NWS Atlanta, GA

April 20, 2011Whitfield County, Georgia

NWS Atlanta, GA issued this flash flood warning at Apr 20, 2011, 8:18 AM EDT for Whitfield County, Georgia. It was in force for 116 min. 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 20, 2011, 8:18 AM EDT (12:18 UTC)
Expired: Apr 20, 2011, 10:14 AM EDT
In force: 116 min
Issued by: NWS Atlanta, GA
Area: Storm-based polygon
Flood severity: None

County Whitfield County, GA

The radar

The Northeast Alabama radar (KHTX), 107 km from the middle of the area, began a volume at 12:18 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, 0.3 hours before the alert went out and 165 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: 1316 J/kg
Mixed-layer CIN: -128 J/kg
Mixed-layer LCL: 466 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 85 m²/s²
0-3 km storm-relative helicity: 57 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

895 
WGUS52 KFFC 201218
FFWFFC
GAC313-201815-
/O.NEW.KFFC.FF.W.0005.110420T1218Z-110420T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
818 AM EDT WED APR 20 2011

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  CENTRAL WHITFIELD COUNTY IN NORTHWEST GEORGIA

* UNTIL 215 PM EDT WEDNESDAY

* AT 807 AM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED   
  STRONG THUNDERSTORMS HAD PRODUCED AROUND TWO INCHES OF RAIN SINCE  
  630 AM EDT THIS MORNING. ADDITIONAL RAINFALL UP TO ANOTHER INCH CAN
  BE EXPECTED BEFORE THE RAIN ENDS LATER THIS MORNING. FLASH FLOODING
  OF SMALL STREAMS AND CREEKS IN THE WARNED AREA CAN BE EXPECTED.    
  THIS INCLUDES THE MILL CREEK BASIN NEAR DALTON.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO TUNNEL     
  HILL AND DALTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

EXCESSIVE RUNOFF FROM HEAVY RAINFALL WILL CAUSE FLOODING OF SMALL
CREEKS AND STREAMS...AS WELL AS HIGHWAYS AND UNDERPASSES.
ADDITIONALLY...COUNTRY ROADS AND FARMLANDS ALONG THE BANKS OF
CREEKS...STREAMS AND OTHER LOW LYING AREAS ARE SUBJECT TO FLOODING.

IF YOU SEE SIGNIFICANT FLOODING CALL THE NATIONAL WEATHER SERVICE
TOLL FREE AT 1 8 6 6 7 6 3 4 4 6 6.

&&

LAT...LON 3487 8482 3485 8485 3482 8486 3480 8484
      3478 8488 3474 8486 3470 8505 3472 8505
      3472 8507 3486 8505 3488 8503 3490 8483

$$

16

1 follow-up statement

592 
WGUS72 KFFC 201414
FFSFFC

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
1014 AM EDT WED APR 20 2011

GAC313-201438-
/O.CAN.KFFC.FF.W.0005.000000T0000Z-110420T1815Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
WHITFIELD GA-
1014 AM EDT WED APR 20 2011

...THE FLASH FLOOD WARNING HAS BEEN CANCELLED FOR CENTRAL WHITFIELD
COUNTY...

STRONG THUNDERSTORMS THIS MORNING PRODUCED RAINFALL AMOUNTS OF 2 TO 
2.5 INCHES IN LESS THAN 2 HOURS. THE WHITFIELD COUNTY EMERGENCY 
MANAGER INDICATED TEMPORARY STREET FLOODING OCCURRED AT THE NORMAL 
LOW LYING AND SLOW DRAINING ROADS IN THE DALTON AREA. AT THIS TIME 
NO STREAMS OR CREEKS CAME OUT OF THEIR BANKS TO CAUSE FLOODING.

CONSEQUENTLY...THE FLASH FLOOD WARNING WILL BE CANCELLED.

IF YOU SEE SIGNIFICANT FLOODING CALL THE NATIONAL WEATHER SERVICE
TOLL FREE AT 1 8 6 6 7 6 3 4 4 6 6.

LAT...LON 3487 8482 3485 8485 3482 8486 3480 8484
      3478 8488 3474 8486 3470 8505 3472 8505
      3472 8507 3486 8505 3488 8503 3490 8483

$$

16

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 20, 7:39 AM EDT	Severe Thunderstorm Warning	FFC	Catoosa, Chattooga, Dade, Floyd, Gordon, Murray and 2 more	51 min
Apr 20, 8:15 AM EDT	Severe Thunderstorm Warning	FFC	Fannin, Gilmer, Gordon, Murray, Pickens, Whitfield	45 min

Nearby

Flash Flood Warnings in Georgia, 2011 Every flash flood warning in 2011

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.