Alert archive / Georgia / Mesoscale Discussions in 2018

Mesoscale Discussion 1117

July 21, 201814 counties in Alabama; 62 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jul 21, 2018, 7:10 AM CDT for 14 counties in Alabama; 62 counties in Georgia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jul 21, 2018, 7:10 AM CDT (12:10 UTC)
Expired
Jul 21, 2018, 9:15 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 76 counties

Calhoun County, AL, Chambers County, AL, Cherokee County, AL, Clay County, AL, Cleburne County, AL, Etowah County, AL, Lee County, AL, Macon County, AL, Marshall County, AL, Randolph County, AL, Russell County, AL, St. Clair County, AL, Talladega County, AL, Tallapoosa County, AL, Baldwin County, GA, Ben Hill County, GA, Bibb County, GA, Bleckley County, GA, Butts County, GA, Carroll County, GA, Chattahoochee County, GA, Clayton County, GA, Coweta County, GA, Crawford County, GA, Crisp County, GA, Dodge County, GA, Dooly County, GA, Douglas County, GA, Emanuel County, GA, Fayette County, GA, Glascock County, GA, Greene County, GA, Hancock County, GA, Haralson County, GA, Harris County, GA, Heard County, GA, Henry County, GA, Houston County, GA, Jasper County, GA, Jeff Davis County, GA, Jefferson County, GA, Johnson County, GA, Jones County, GA, Lamar County, GA, Laurens County, GA, Lee County, GA, Macon County, GA, Marion County, GA, Meriwether County, GA, Monroe County, GA, Montgomery County, GA, Morgan County, GA, Muscogee County, GA, Newton County, GA, Peach County, GA, Pike County, GA, Pulaski County, GA, Putnam County, GA, Schley County, GA, Spalding County, GA, Stewart County, GA, Sumter County, GA, Talbot County, GA, Taliaferro County, GA, Taylor County, GA, Telfair County, GA, Toombs County, GA, Treutlen County, GA, Troup County, GA, Twiggs County, GA, Upson County, GA, Washington County, GA, Webster County, GA, Wheeler County, GA, Wilcox County, GA, Wilkinson County, GA

The radar

The Atlanta radar (KFFC), 16 km from the middle of the area, began a volume at 12:13 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

Birmingham, AL (KBMX), launched 12:00Z, 0.2 hours before the alert went out and 196 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, Birmingham, AL at 12:00Z on 2018-07-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 2831 joules per kilogram.LCLLFCEL10008507005003002001001 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, Birmingham, AL at 12:00Z on 2018-07-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 245 square meters per square second.1939587897Sfc1 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
2831 J/kg
Mixed-layer CIN
-66 J/kg
Mixed-layer LCL
906 m above ground
0-6 km bulk shear
37 kt
0-1 km storm-relative helicity
245 m²/s²
0-3 km storm-relative helicity
283 m²/s²
Significant tornado parameter
3.6
Supercell composite
24.7

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.

IssuedProductOfficeCountiesLasted
Jul 20, 10:20 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lauderdale, Lawrence, Limestone, Madison and 1 more115 min
Jul 21, 1:38 AM CDTMesoscale DiscussionSPCBlount, Colbert, Cullman, DeKalb, Etowah, Franklin and 10 more67 min
Jul 21, 2:00 AM CDTSevere Thunderstorm WatchSPCBlount, Calhoun, Chambers, Cherokee, Clay, Cleburne and 10 more7 hr
Jul 21, 4:35 AM CDTMesoscale DiscussionSPCCalhoun, Chambers, Cherokee, Clay, Cleburne, DeKalb and 6 more115 min
Jul 21, 10:12 AM CDTSevere Thunderstorm WatchSPCHenry, Houston5 hr
Jul 21, 2:37 PM CDTMesoscale DiscussionSPCCherokee, Cleburne, DeKalb, Randolph2 hr
Jul 21, 4:42 PM CDTSevere Thunderstorm WatchSPCBarbour, Bullock, Calhoun, Chambers, Cherokee, Clay and 9 more8 hr
Jul 21, 6:24 PM CDTMesoscale DiscussionSPCBullock, Calhoun, Chambers, Cherokee, Clay, Cleburne and 6 more96 min
Jul 21, 6:50 PM CDTSevere Thunderstorm WatchSPCHenry, Houston5 hr
Jul 20, 7:02 PM CDTTornado WatchSPCCatoosa, Dade, Murray, Walker, Whitfield7 hr
Jul 21, 9:30 AM CDTMesoscale DiscussionSPCAtkinson, Baker, Berrien, Brooks, Clinch, Coffee and 14 more90 min

Nearby

Mesoscale Discussions in Georgia, 2018Mesoscale Discussions in Alabama, 2018Every 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.