Alert archive / Georgia / Mesoscale Discussions in 2018

Mesoscale Discussion 910

June 27, 201814 counties in Alabama; 47 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jun 27, 2018, 5:24 PM CDT for 14 counties in Alabama; 47 counties in Georgia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 27, 2018, 5:24 PM CDT (22:24 UTC)
Expired: Jun 27, 2018, 7:30 PM CDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 61 counties

Calhoun County, AL, Chambers County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Elmore County, AL, Lee County, AL, Macon County, AL, Montgomery County, AL, Randolph County, AL, Shelby County, AL, Talladega County, AL, Tallapoosa County, AL, Baldwin County, GA, Banks County, GA, Barrow County, GA, Bibb County, GA, Butts County, GA, Carroll County, GA, Clarke County, GA, Clayton County, GA, Cobb County, GA, Coweta County, GA, Crawford County, GA, DeKalb County, GA, Douglas County, GA, Fayette County, GA, Fulton County, GA, Glascock County, GA, Greene County, GA, Gwinnett County, GA, Hancock County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Jackson County, GA, Jasper County, GA, Jefferson County, GA, Jones County, GA, Lamar County, GA, Madison County, GA, Meriwether County, GA, Monroe County, GA, Morgan County, GA, Newton County, GA, Oconee County, GA, Oglethorpe County, GA, Pike County, GA, Putnam County, GA, Rockdale County, GA, Spalding County, GA, Talbot County, GA, Taliaferro County, GA, Troup County, GA, Upson County, GA, Walton County, GA, Warren County, GA, Washington County, GA, Wilkes County, GA

The radar

The Atlanta radar (KFFC), 15 km from the middle of the area, began a volume at 22:24 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, 10.4 hours before the alert went out and 19 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: 440 J/kg
Mixed-layer CIN: -104 J/kg
Mixed-layer LCL: 883 m above ground
0-6 km bulk shear: 15 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.6

Open this sounding in Storm Lab

The text

As transmitted.

537 
ACUS11 KWNS 272225
SWOMCD
SPC MCD 272224 
GAZ000-ALZ000-280030-

Mesoscale Discussion 0910
NWS Storm Prediction Center Norman OK
0524 PM CDT Wed Jun 27 2018

Areas affected...Central Georgia/Alabama

Concerning...Severe potential...Watch unlikely 

Valid 272224Z - 280030Z

Probability of Watch Issuance...20 percent

SUMMARY...A broken line of storms continues moving southeastward
across central Alabama/Georgia. Strong wind gusts are the main
threat although hail is possible.

DISCUSSION...An upper-level shortwave trough is providing ascent
aloft helping to sustain a line of storms across central
Alabama/Georgia. Convective temperatures are being breached and
outflow along the leading edge of storms is helping to develop
storms as the line moves southeastward. This QLCS should continue
southeastward as it moves through a moderate buoyancy/weak shear
environment (MLCAPE of 2000-2500 J/kg; effective bulk shear 20-25
knots per mesoanalysis). Mesoanalysis and RAP soundings show steeper
low-level lapse rates (7+ C/km) and DCAPE > 1000 J/kg along/ahead of
the QLCS indicating the potential for strong wind gusts and possibly
severe wind. The QLCS should continue into the evening with some
weakening after sunset. A watch issuance is unlikely given the
anticipated isolated severe threat.

..Nauslar/Cook/Edwards.. 06/27/2018

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...CAE...GSP...FFC...BMX...

LAT...LON   33298690 33588631 33828577 33908484 34098398 34368355
            34358304 33678268 33078231 32768338 32538481 32128646
            33298690

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 27, 1:29 PM CDT	Mesoscale Discussion	SPC	Banks, Catoosa, Fannin, Franklin, Gilmer, Habersham and 9 more	3 hr
Jun 27, 2:36 PM CDT	Severe Thunderstorm Watch	SPC	Columbia, Elbert, Franklin, Habersham, Hart, Lincoln and 4 more	5 hr
Jun 27, 4:55 PM CDT	Mesoscale Discussion	SPC	Columbia, Elbert, Lincoln, McDuffie, Richmond, Wilkes	2 hr

Nearby

Mesoscale Discussions in Georgia, 2018 Mesoscale Discussions in Alabama, 2018 Every mesoscale discussion in 2018

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.