Alert archive / Tennessee / Mesoscale Discussions in 2018

Mesoscale Discussion 906

June 27, 20185 states

The Storm Prediction Center issued this mesoscale discussion at Jun 27, 2018, 2:29 PM EDT for 5 states. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued
Jun 27, 2018, 2:29 PM EDT (18:29 UTC)
Expired
Jun 27, 2018, 5:00 PM EDT
In force
3 hr
Issued by
the Storm Prediction Center
Chance of a watch
40%
All 103 counties

Banks County, GA, Catoosa County, GA, Fannin County, GA, Franklin County, GA, Gilmer County, GA, Habersham County, GA, Hart County, GA, Lumpkin County, GA, Murray County, GA, Rabun County, GA, Stephens County, GA, Towns County, GA, Union County, GA, White County, GA, Whitfield County, GA, Allen County, KY, Barren County, KY, Clinton County, KY, Cumberland County, KY, Edmonson County, KY, Metcalfe County, KY, Monroe County, KY, Simpson County, KY, Warren County, KY, Buncombe County, NC, Burke County, NC, Cabarrus County, NC, Catawba County, NC, Cherokee County, NC, Clay County, NC, Cleveland County, NC, Gaston County, NC, Graham County, NC, Haywood County, NC, Henderson County, NC, Iredell County, NC, Jackson County, NC, Lincoln County, NC, Macon County, NC, Madison County, NC, McDowell County, NC, Mecklenburg County, NC, Polk County, NC, Rowan County, NC, Rutherford County, NC, Stanly County, NC, Swain County, NC, Transylvania County, NC, Union County, NC, Abbeville County, SC, Anderson County, SC, Cherokee County, SC, Chester County, SC, Fairfield County, SC, Greenville County, SC, Lancaster County, SC, Laurens County, SC, Newberry County, SC, Oconee County, SC, Pickens County, SC, Spartanburg County, SC, Union County, SC, York County, SC, Anderson County, TN, Bledsoe County, TN, Blount County, TN, Bradley County, TN, Cannon County, TN, Clay County, TN, Cocke County, TN, Coffee County, TN, Cumberland County, TN, DeKalb County, TN, Fentress County, TN, Grundy County, TN, Hamilton County, TN, Jackson County, TN, Jefferson County, TN, Knox County, TN, Loudon County, TN, Macon County, TN, Marion County, TN, McMinn County, TN, Meigs County, TN, Monroe County, TN, Morgan County, TN, Overton County, TN, Pickett County, TN, Polk County, TN, Putnam County, TN, Rhea County, TN, Roane County, TN, Rutherford County, TN, Scott County, TN, Sequatchie County, TN, Sevier County, TN, Smith County, TN, Sumner County, TN, Trousdale County, TN, Van Buren County, TN, Warren County, TN, White County, TN, Wilson County, TN

The radar

The Knoxville radar (KMRX), 68 km from the middle of the area, began a volume at 18:33 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, 6.5 hours before the alert went out and 270 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 2018-06-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 440 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 2018-06-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 82 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
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.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 27, 3:36 PM EDTSevere Thunderstorm WatchSPCColumbia, Elbert, Franklin, Habersham, Hart, Lincoln and 4 more5 hr
Jun 27, 5:55 PM EDTMesoscale DiscussionSPCColumbia, Elbert, Lincoln, McDuffie, Richmond, Wilkes2 hr
Jun 27, 6:24 PM EDTMesoscale DiscussionSPCBaldwin, Banks, Barrow, Bibb, Butts, Carroll and 41 more2 hr
Jun 26, 8:41 PM EDTMesoscale DiscussionSPCBallard, Breckinridge, Butler, Caldwell, Calloway, Carlisle and 25 more2 hr
Jun 26, 11:06 PM EDTMesoscale DiscussionSPCButler, Logan, Todd84 min
Jun 27, 2:42 PM EDTMesoscale DiscussionSPCBallard, Calloway, Carlisle, Fulton, Graves, Hickman and 4 more93 min

Nearby

Mesoscale Discussions in Tennessee, 2018Mesoscale Discussions in North Carolina, 2018Mesoscale Discussions in Georgia, 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.