Alert archive / Georgia / Mesoscale Discussions in 2015

Mesoscale Discussion 1421

July 14, 201517 counties in Alabama; 62 counties in Georgia; 5 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2015, 6:36 PM CDT for 17 counties in Alabama; 62 counties in Georgia; 5 counties in South Carolina. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued
Jul 14, 2015, 6:36 PM CDT (23:36 UTC)
Expired
Jul 14, 2015, 8:30 PM CDT
In force
114 min
Issued by
the Storm Prediction Center
Chance of a watch
60%
All 84 counties

Autauga County, AL, Bibb County, AL, Chambers County, AL, Chilton County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Elmore County, AL, Jefferson County, AL, Lee County, AL, Macon County, AL, Randolph County, AL, Russell County, AL, Shelby County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Baldwin County, GA, Bibb County, GA, Bleckley County, GA, Burke County, GA, Butts County, GA, Carroll County, GA, Chattahoochee County, GA, Clayton County, GA, Columbia County, GA, Coweta County, GA, Crawford 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, Harris County, GA, Heard County, GA, Henry County, GA, Houston County, GA, Jasper County, GA, Jefferson County, GA, Jenkins County, GA, Johnson County, GA, Jones County, GA, Lamar County, GA, Laurens County, GA, Lincoln County, GA, Macon County, GA, Marion County, GA, McDuffie County, GA, Meriwether County, GA, Monroe County, GA, Morgan County, GA, Muscogee County, GA, Newton County, GA, Oconee County, GA, Oglethorpe County, GA, Peach County, GA, Pike County, GA, Pulaski County, GA, Putnam County, GA, Richmond County, GA, Rockdale County, GA, Schley County, GA, Screven County, GA, Spalding County, GA, Talbot County, GA, Taliaferro County, GA, Taylor County, GA, Treutlen County, GA, Troup County, GA, Twiggs County, GA, Upson County, GA, Walton County, GA, Warren County, GA, Washington County, GA, Wilkes County, GA, Wilkinson County, GA, Aiken County, SC, Allendale County, SC, Barnwell County, SC, Edgefield County, SC, McCormick County, SC

The radar

The Atlanta radar (KFFC), 30 km from the middle of the area, began a volume at 23:37 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, 11.6 hours before the alert went out and 33 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 2015-07-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1704 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, Peachtre/Fal Fld, GA at 12:00Z on 2015-07-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -31 square meters per square second.1939Sfc1 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
1704 J/kg
Mixed-layer CIN
-38 J/kg
Mixed-layer LCL
988 m above ground
0-6 km bulk shear
18 kt
0-1 km storm-relative helicity
-31 m²/s²
0-3 km storm-relative helicity
-39 m²/s²
Significant tornado parameter
0.0
Supercell composite
-1.1

Open this sounding in Storm Lab

The text

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

409 
ACUS11 KWNS 142337
SWOMCD
SPC MCD 142336 
SCZ000-GAZ000-ALZ000-150130-

MESOSCALE DISCUSSION 1421
NWS STORM PREDICTION CENTER NORMAN OK
0636 PM CDT TUE JUL 14 2015

AREAS AFFECTED...CENTRAL ALABAMA...CENTRAL GEORGIA...AND WESTERN
SOUTH CAROLINA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 142336Z - 150130Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...ONGOING STRONG/SEVERE MESOSCALE CONVECTIVE COMPLEX WILL
MOVE SOUTH INTO THE DISCUSSION AREA BETWEEN 01-02Z.  TRENDS ARE
BEING MONITORED FOR A POSSIBLE SEVERE THUNDERSTORM WATCH ISSUANCE.

DISCUSSION...ONGOING MESOSCALE CONVECTIVE COMPLEX IS MOVING SOUTH AT
APPROXIMATELY 30 KNOTS ALONG THE LEADING EDGE OF A MATURE COLD POOL
OVER NORTHEASTERN MISSISSIPPI...FAR NORTHERN ALABAMA...AND FAR
NORTHERN GEORGIA.  STRONG INSTABILITY /2000-3000 J/KG MLCAPE/ IS
PRESENT SOUTH OF THIS COLD POOL...WHICH SHOULD MAINTAIN THE SEVERE
THREAT AT LEAST THROUGH 01-02Z ACROSS WW 424 AND MAY SUSTAIN THE
COMPLEX AS IT MOVES INTO THE DISCUSSION AREA.  HOWEVER...THE LOSS OF
INSOLATION WILL DECREASE INSTABILITY SOMEWHAT AND MAY LEAD TO A
GRADUAL WEAKENING OF THE COMPLEX WITH SOUTHWARD/EASTWARD EXTENT. 
NEVERTHELESS...AT LEAST AN ISOLATED DAMAGING WIND THREAT IS EXPECTED
WITH THIS ACTIVITY AFTER 01Z ACROSS THE DISCUSSION AREA...AND A NEW
SEVERE THUNDERSTORM WATCH MAY BE NEEDED TO ADDRESS THIS THREAT. 
TRENDS ARE BEING MONITORED.

..COOK/EDWARDS.. 07/14/2015

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

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

LAT...LON   33408777 33648711 33718476 33868325 34048236 33758151
            33158121 32608155 32188293 32058462 32348600 32578706
            32938776 33408777

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 14, 12:14 PM CDTMesoscale DiscussionSPCJackson91 min
Jul 14, 2:41 PM CDTMesoscale DiscussionSPCColbert, Jackson, Lauderdale, Limestone, Madison94 min
Jul 14, 3:55 PM CDTMesoscale DiscussionSPCBlount, Cherokee, Colbert, Cullman, DeKalb, Etowah and 10 more65 min
Jul 14, 3:59 PM CDTSevere Thunderstorm WatchSPCBlount, Calhoun, Cherokee, Cleburne, Colbert, Cullman and 17 more7 hr
Jul 14, 5:24 PM CDTMesoscale DiscussionSPCBlount, Calhoun, Cherokee, Cleburne, Colbert, Cullman and 17 more2 hr
Jul 13, 7:06 PM CDTMesoscale DiscussionSPCCherokee, Chester, Lancaster, Union, York84 min
Jul 13, 9:34 PM CDTMesoscale DiscussionSPCChesterfield, Fairfield, Kershaw, Lancaster86 min

Nearby

Mesoscale Discussions in Georgia, 2015Mesoscale Discussions in Alabama, 2015Mesoscale Discussions in South Carolina, 2015Every mesoscale discussion in 2015

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.