Alert archive / Georgia / Mesoscale Discussions in 2013

Mesoscale Discussion 451

April 11, 201317 counties in Alabama; 50 counties in Georgia; 8 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 11, 2013, 5:54 PM CDT for 17 counties in Alabama; 50 counties in Georgia; 8 counties in South Carolina. It was in force for 96 min.

The area

The outline as issued.

The facts

Issued
Apr 11, 2013, 5:54 PM CDT (22:54 UTC)
Expired
Apr 11, 2013, 7:30 PM CDT
In force
96 min
Issued by
the Storm Prediction Center
All 75 counties

Autauga County, AL, Bullock County, AL, Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, DeKalb County, AL, Elmore County, AL, Etowah County, AL, Lee County, AL, Macon County, AL, Montgomery County, AL, Randolph County, AL, Talladega County, AL, Tallapoosa County, AL, Banks County, GA, Barrow County, GA, Bartow County, GA, Carroll County, GA, Chattooga County, GA, Cherokee County, GA, Clarke County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, Dawson County, GA, DeKalb County, GA, Douglas County, GA, Elbert County, GA, Fayette County, GA, Floyd County, GA, Forsyth County, GA, Franklin County, GA, Fulton County, GA, Gilmer County, GA, Gordon County, GA, Gwinnett County, GA, Habersham County, GA, Hall County, GA, Haralson County, GA, Harris County, GA, Hart County, GA, Heard County, GA, Henry County, GA, Jackson County, GA, Lumpkin County, GA, Madison County, GA, Meriwether County, GA, Murray County, GA, Newton County, GA, Oconee County, GA, Oglethorpe County, GA, Paulding County, GA, Pickens County, GA, Pike County, GA, Polk County, GA, Rockdale County, GA, Spalding County, GA, Stephens County, GA, Troup County, GA, Union County, GA, Walker County, GA, Walton County, GA, White County, GA, Whitfield County, GA, Abbeville County, SC, Anderson County, SC, Greenville County, SC, Greenwood County, SC, Laurens County, SC, Oconee County, SC, Pickens County, SC, Spartanburg County, SC

The radar

The Atlanta radar (KFFC), 58 km from the middle of the area, began a volume at 22:54 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 10.9 hours before the alert went out and 60 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 2013-04-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°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 2013-04-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 121 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1029 m above ground
0-6 km bulk shear
29 kt
0-1 km storm-relative helicity
121 m²/s²
0-3 km storm-relative helicity
123 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.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 11, 10:41 AM CDTMesoscale DiscussionSPCColbert, Cullman, Fayette, Franklin, Greene, Hale and 12 more2 hr
Apr 11, 11:56 AM CDTTornado WatchSPCAutauga, Bibb, Blount, Chilton, Colbert, Coosa and 31 more7 hr
Apr 11, 12:59 PM CDTMesoscale DiscussionSPCBaldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 5 more91 min
Apr 11, 1:30 PM CDTTornado WatchSPCBaldwin, Butler, Choctaw, Clarke, Conecuh, Covington and 6 more8 hr
Apr 11, 2:21 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Chilton, Coosa, Cullman and 12 more84 min
Apr 11, 3:26 PM CDTMesoscale DiscussionSPCChambers, Cleburne, Lee, Randolph, Russell94 min
Apr 11, 3:45 PM CDTTornado WatchSPCBarbour, Bullock, Calhoun, Chambers, Cherokee, Clay and 9 more6 hr
Apr 11, 5:03 PM CDTMesoscale DiscussionSPCCoffee, Dale, Geneva, Henry, Houston2 hr
Apr 11, 5:35 PM CDTMesoscale DiscussionSPCBaldwin, Butler, Conecuh, Covington, Crenshaw, Escambia and 2 more115 min

Nearby

Mesoscale Discussions in Georgia, 2013Mesoscale Discussions in Alabama, 2013Mesoscale Discussions in South Carolina, 2013Every mesoscale discussion in 2013

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.