Alert archive / Georgia / Mesoscale Discussions in 2017

Mesoscale Discussion 820

May 23, 20177 counties in Alabama; 21 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at May 23, 2017, 7:12 PM CDT for 7 counties in Alabama; 21 counties in Georgia. It was in force for 93 min.

The area

The outline as issued.

The facts

Issued: May 23, 2017, 7:12 PM CDT (00:12 UTC)
Expired: May 23, 2017, 8:45 PM CDT
In force: 93 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 28 counties

Chambers County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Randolph County, AL, Tallapoosa County, AL, Bartow County, GA, Carroll County, GA, Cherokee County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, Dawson County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Floyd County, GA, Forsyth County, GA, Fulton County, GA, Gordon County, GA, Gwinnett County, GA, Haralson County, GA, Heard County, GA, Paulding County, GA, Pickens County, GA, Polk County, GA, Troup County, GA

The radar

The Atlanta radar (KFFC), 52 km from the middle of the area, began a volume at 00:16 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

Nashville Metro, TN (KBNA), launched 00:00Z, 0.2 hours before the alert went out and 310 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: 2 J/kg
Mixed-layer CIN: -25 J/kg
Mixed-layer LCL: 1676 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: -2 m²/s²
0-3 km storm-relative helicity: 56 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

As transmitted.

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SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 24, 6:41 AM CDT	Mesoscale Discussion	SPC	Blount, Calhoun, Cherokee, Cleburne, DeKalb, Etowah and 6 more	3 hr
May 23, 7:46 PM CDT	Mesoscale Discussion	SPC	Appling, Bacon, Brantley, Bryan, Bulloch, Candler and 12 more	89 min
May 24, 5:56 AM CDT	Tornado Watch	SPC	Brooks, Decatur, Grady, Lowndes, Seminole, Thomas	8 hr
May 24, 7:29 AM CDT	Mesoscale Discussion	SPC	Appling, Atkinson, Bacon, Baker, Baldwin, Ben Hill and 83 more	3 hr
May 24, 9:04 AM CDT	Tornado Watch	SPC	Banks, Barrow, Bartow, Carroll, Catoosa, Chattooga and 50 more	11 hr
May 24, 9:26 AM CDT	Mesoscale Discussion	SPC	Decatur, Grady, Seminole	94 min
May 24, 10:03 AM CDT	Tornado Watch	SPC	Appling, Atkinson, Bacon, Baker, Baldwin, Ben Hill and 96 more	10 hr
May 24, 1:10 PM CDT	Mesoscale Discussion	SPC	Appling, Atkinson, Bacon, Baker, Baldwin, Ben Hill and 99 more	95 min
May 24, 2:02 PM CDT	Mesoscale Discussion	SPC	Banks, Barrow, Bartow, Carroll, Cherokee, Clarke and 43 more	88 min
May 24, 4:25 PM CDT	Mesoscale Discussion	SPC	Appling, Atkinson, Bacon, Baldwin, Banks, Barrow and 87 more	65 min

Nearby

Mesoscale Discussions in Georgia, 2017 Mesoscale Discussions in Alabama, 2017 Every mesoscale discussion 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; radar from the NEXRAD Level II archive.