Alert archive / Georgia / Flash Flood Warnings in 2012

Flash Flood Warning 20, NWS Atlanta, GA

October 1, 2012Hall County, Georgia

NWS Atlanta, GA issued this flash flood warning at Oct 1, 2012, 9:23 PM EDT for Hall County, Georgia. It was in force for 6 hr. 1 report 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 1, 2012, 9:23 PM EDT (01:23 UTC)
Expired: Oct 2, 2012, 3:15 AM EDT
In force: 6 hr
Issued by: NWS Atlanta, GA
Area: Storm-based polygon
Flood severity: None

County Hall County, GA

The radar

The Atlanta radar (KFFC), 124 km from the middle of the area, began a volume at 01:23 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

Time	Report	Where	Remark
Oct 1, 10:15 PM EDT	FLASH FLOOD	2 Nw Gainesville, GA	HALL COUNTY ROAD DEPARTMENT REPORTED SOME GRAVEL ROADS WASHED OUT ALONG WITH SOME ROAD CLOSURES NORTHWEST OF GAINESVILLE. ROADS CLOSED WERE...BEN LEE ROAD....AND HIGHWAY 60 NW OF GAINESVILLE.

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 00:00Z, 1.4 hours before the alert went out and 120 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: 988 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 481 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 263 m²/s²
0-3 km storm-relative helicity: 292 m²/s²
Significant tornado parameter: 1.8
Supercell composite: 6.7

Open this sounding in Storm Lab

The text

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

688 
WGUS52 KFFC 020123
FFWFFC
GAC139-020715-
/O.NEW.KFFC.FF.W.0020.121002T0123Z-121002T0715Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE PEACHTREE CITY GA
923 PM EDT MON OCT 1 2012

THE NATIONAL WEATHER SERVICE IN PEACHTREE CITY HAS ISSUED A

* FLASH FLOOD WARNING FOR...
  SOUTHERN HALL COUNTY IN NORTH CENTRAL GEORGIA

* UNTIL 315 AM EDT

* AT 918 PM EDT...LOCAL LAW ENFORCEMENT OFFICIALS REPORTED FLASH   
FLOODING FROM HEAVY RAINFALL IN GAINESVILLE. DOPPLER RADAR HAS 
INDICATED WIDESPREAD AMOUNTS OF 2 TO 3 INCHES ACROSS THE WARNED AREA 
WITH THE LAST TWO HOURS.

* LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO LULA AND
  GAINESVILLE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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. LAW ENFORCEMENT 
HAS ALREADY REPORTED A FEW ROAD CLOSURES IN DOWNTOWN GAINESVILLE.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE THE
DANGERS OF FLOODING. IF FLASH FLOODING IS OBSERVED ACT QUICKLY. MOVE
UP TO HIGHER GROUND TO ESCAPE FLOOD WATERS. DO NOT STAY IN AREAS
SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

IF YOU SEE SIGNIFICANT FLOODING CALL THE NATIONAL WEATHER SERVICE
TOLL FREE AT 1 8 6 6 7 6 3 4 4 6 6. YOU CAN ALSO TWEET YOUR REPORT
USING HASHTAG GAWX.

&&

LAT...LON 3438 8366 3422 8373 3411 8385 3412 8390
      3419 8395 3428 8391 3437 8381 3439 8366

$$

The office that day

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

Issued	Product	Office	Counties	Lasted
Oct 1, 10:17 PM EDT	Flash Flood Warning	FFC	Meriwether, Pike, Spalding, Upson	3 hr
Oct 1, 10:45 PM EDT	Special Weather Statement	FFC	DeKalb, Gwinnett	60 min
Oct 1, 10:54 PM EDT	Special Weather Statement	FFC	Dade	36 min
Oct 1, 10:56 PM EDT	Flash Flood Warning	FFC	DeKalb, Gwinnett	6 hr
Oct 2, 1:18 AM EDT	River Flood Warning	FFC	Gwinnett	3 hr
Oct 2, 1:18 AM EDT	River Flood Warning	FFC	Gwinnett	6 hr
Oct 2, 2:49 AM EDT	Flash Flood Warning	FFC	White	5 hr
Oct 2, 4:10 AM EDT	River Flood Warning	FFC	Gwinnett, Walton	6 hr
Oct 2, 6:41 AM EDT	River Flood Warning	FFC	Gwinnett	18 hr
Oct 2, 11:26 AM EDT	River Flood Warning	FFC	DeKalb, Rockdale	8 hr

Nearby

Flash Flood Warnings in Georgia, 2012 Every flash flood warning in 2012

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.