Alert archive / Georgia / Mesoscale Discussions in 2015

Mesoscale Discussion 406

April 20, 201523 counties in Georgia; 21 counties in North Carolina; 22 counties in South Carolina

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2015, 6:45 PM EDT for 23 counties in Georgia; 21 counties in North Carolina; 22 counties in South Carolina. It was in force for 60 min.

The area

The outline as issued.

The facts

Issued
Apr 20, 2015, 6:45 PM EDT (22:45 UTC)
Expired
Apr 20, 2015, 7:45 PM EDT
In force
60 min
Issued by
the Storm Prediction Center
All 66 counties

Banks County, GA, Barrow County, GA, Clarke County, GA, DeKalb County, GA, Elbert County, GA, Forsyth County, GA, Franklin County, GA, Fulton County, GA, Gwinnett County, GA, Habersham County, GA, Hall County, GA, Hart County, GA, Jackson County, GA, Lincoln County, GA, Madison County, GA, Oconee County, GA, Oglethorpe County, GA, Rabun County, GA, Rockdale County, GA, Stephens County, GA, Walton County, GA, White County, GA, Wilkes County, GA, Alexander County, NC, Anson County, NC, Avery County, NC, Buncombe County, NC, Burke County, NC, Caldwell County, NC, Catawba County, NC, Cleveland County, NC, Davie County, NC, Gaston County, NC, Henderson County, NC, Iredell County, NC, Jackson County, NC, Lincoln County, NC, McDowell County, NC, Mitchell County, NC, Polk County, NC, Rutherford County, NC, Transylvania County, NC, Union County, NC, Yancey County, NC, Abbeville County, SC, Anderson County, SC, Cherokee County, SC, Chester County, SC, Chesterfield County, SC, Edgefield County, SC, Fairfield County, SC, Greenville County, SC, Greenwood County, SC, Kershaw County, SC, Lancaster County, SC, Laurens County, SC, Lexington County, SC, McCormick County, SC, Newberry County, SC, Oconee County, SC, Pickens County, SC, Richland County, SC, Saluda County, SC, Spartanburg County, SC, Union County, SC, York County, SC

The nearest sounding before it

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 10.8 hours before the alert went out and 241 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, Greensboro/Hi Pt, NC at 12:00Z on 2015-04-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 17 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, Greensboro/Hi Pt, NC at 12:00Z on 2015-04-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 59 square meters per square second.19395878Sfc1 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
17 J/kg
Mixed-layer CIN
-48 J/kg
Mixed-layer LCL
654 m above ground
0-6 km bulk shear
39 kt
0-1 km storm-relative helicity
59 m²/s²
0-3 km storm-relative helicity
77 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.4

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 20, 2:09 AM EDTSevere Thunderstorm WatchSPCCatoosa, Chattooga, Dade, Floyd, Gordon, Walker and 1 more4 hr
Apr 20, 3:36 AM EDTMesoscale DiscussionSPCCatoosa, Chattooga, Dade, Floyd, Gordon, Murray and 2 more84 min
Apr 20, 11:04 AM EDTSevere Thunderstorm WatchSPCAppling, Atkinson, Bacon, Baker, Ben Hill, Berrien and 25 more8 hr
Apr 20, 1:03 PM EDTMesoscale DiscussionSPCBanks, Clarke, Elbert, Franklin, Habersham, Hall and 7 more57 min
Apr 20, 1:23 PM EDTTornado WatchSPCBanks, Barrow, Clarke, Clayton, Cobb, Coweta and 22 more7 hr
Apr 20, 4:18 PM EDTMesoscale DiscussionSPCBanks, Barrow, Clarke, Elbert, Franklin, Habersham and 9 more57 min
Apr 20, 4:36 PM EDTTornado WatchSPCLincoln5 hr
Apr 19, 9:06 PM EDTMesoscale DiscussionSPCBladen, Brunswick, Duplin, Durham, Edgecombe, Franklin and 13 more54 min
Apr 20, 2:25 AM EDTMesoscale DiscussionSPCBeaufort, Bertie, Camden, Chowan, Craven, Currituck and 16 more95 min
Apr 20, 1:54 PM EDTMesoscale DiscussionSPCAlleghany, Stokes, Surry3 hr
Apr 20, 2:55 PM EDTSevere Thunderstorm WatchSPCAlamance, Alleghany, Anson, Ashe, Bertie, Caswell and 33 more7 hr
Apr 20, 6:27 PM EDTMesoscale DiscussionSPCAlamance, Alleghany, Caswell, Chatham, Durham, Forsyth and 16 more93 min

Nearby

Mesoscale Discussions in Georgia, 2015Mesoscale Discussions in South Carolina, 2015Mesoscale Discussions in North 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.