Alert archive / North Carolina / Mesoscale Discussions in 2011

Mesoscale Discussion 1968

August 13, 20115 states

The Storm Prediction Center issued this mesoscale discussion at Aug 13, 2011, 4:20 PM EDT for 5 states. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Aug 13, 2011, 4:20 PM EDT (20:20 UTC)
Expired: Aug 13, 2011, 6:15 PM EDT
In force: 115 min
Issued by: the Storm Prediction Center

All 115 counties

Baldwin County, GA, Burke County, GA, Clarke County, GA, Columbia County, GA, Elbert County, GA, Franklin County, GA, Glascock County, GA, Greene County, GA, Hancock County, GA, Hart County, GA, Jefferson County, GA, Jenkins County, GA, Lincoln County, GA, Madison County, GA, McDuffie County, GA, Oglethorpe County, GA, Putnam County, GA, Richmond County, GA, Screven County, GA, Stephens County, GA, Taliaferro County, GA, Warren County, GA, Washington County, GA, Wilkes County, GA, Alexander County, NC, Alleghany County, NC, Anson County, NC, Ashe County, NC, Burke County, NC, Cabarrus County, NC, Caldwell County, NC, Caswell County, NC, Catawba County, NC, Cleveland County, NC, Davidson County, NC, Davie County, NC, Forsyth County, NC, Gaston County, NC, Guilford County, NC, Henderson County, NC, Iredell County, NC, Lincoln County, NC, McDowell County, NC, Mecklenburg County, NC, Montgomery County, NC, Polk County, NC, Randolph County, NC, Rockingham County, NC, Rowan County, NC, Rutherford County, NC, Stanly County, NC, Stokes County, NC, Surry County, NC, Union County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Abbeville County, SC, Aiken County, SC, Allendale County, SC, Anderson County, SC, Bamberg County, SC, Barnwell County, SC, Calhoun County, SC, Cherokee County, SC, Chester County, SC, Chesterfield County, SC, Clarendon County, SC, Darlington County, SC, Edgefield County, SC, Fairfield County, SC, Greenville County, SC, Greenwood County, SC, Hampton County, SC, Kershaw County, SC, Lancaster County, SC, Laurens County, SC, Lee County, SC, Lexington County, SC, McCormick County, SC, Newberry County, SC, Oconee County, SC, Orangeburg County, SC, Pickens County, SC, Richland County, SC, Saluda County, SC, Spartanburg County, SC, Sumter County, SC, Union County, SC, York County, SC, Alleghany County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Carroll County, VA, City of Covington, VA, City of Danville, VA, City of Galax, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Giles County, VA, Grayson County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Wythe County, VA, Monroe County, WV

The radar

The Greer radar (KGSP), 114 km from the middle of the area, began a volume at 20:19 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

Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 8.3 hours before the alert went out and 138 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 6909 m above ground
0-6 km bulk shear: 46 kt
0-1 km storm-relative helicity: 27 m²/s²
0-3 km storm-relative helicity: 126 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

246 
ACUS11 KWNS 132020
SWOMCD
SPC MCD 132020 
VAZ000-NCZ000-SCZ000-WVZ000-GAZ000-TNZ000-132215-

MESOSCALE DISCUSSION 1968
NWS STORM PREDICTION CENTER NORMAN OK
0320 PM CDT SAT AUG 13 2011

AREAS AFFECTED...FAR SERN WV...WRN VA...WRN NC...CNTRL/WRN SC...ERN
GA

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 132020Z - 132215Z

ISOLATED STORMS COULD PRODUCE DMGG WIND GUSTS INTO THE LATE
AFTERNOON HOURS. THE LACK OF CONVECTIVE ORGANIZATION AND ISOLATED
NATURE OF THE SVR THREAT SHOULD PRECLUDE THE NEED FOR A WW.

THE AIR MASS ACROSS MUCH OF THE DISCUSSION AREA HAS BECOME
MODERATELY UNSTABLE /I.E. MLCAPE VALUES OF 1000-2500 J PER KG/ OWING
TO SUFFICIENT HEATING AMIDST RICH BOUNDARY-LAYER MOISTURE -- SFC
DEWPOINTS IN THE UPPER 60S TO THE LOWER 70S. OROGRAPHIC ASCENT OVER
THE CNTRL/SRN APPALACHIANS...COMBINED WITH WEAK SFC CONVERGENCE
ALONG A REMNANT FRONT AND ATTENDANT SFC LOW OVER NRN/ERN GA AND SRN
SC...HAS SUPPORTED THE DEVELOPMENT OF SCATTERED CONVECTION THIS
AFTERNOON. FURTHERMORE...THE GLANCING INFLUENCE OF A SUBTLE
MID-LEVEL IMPULSE SWINGING THROUGH ERN KY...EVIDENT IN RECENT WATER
VAPOR IMAGERY...COULD PROVIDE SUFFICIENT ASCENT FOR AN INCREASE IN
CONVECTION ACROSS PORTIONS OF SWRN VA AND FAR SERN WV BETWEEN
21-00Z. WITH THE STRONGER MID-LEVEL FLOW DISPLACED TO THE NW OF THE
REGION...EFFECTIVE BULK SHEAR MAGNITUDES AOB 20 KT WILL MAINTAIN
PRIMARILY A PULSE CONVECTIVE MODE. AS STORMS COLLAPSE...A THREAT FOR
WET MICROBURSTS PRODUCING DMGG WIND GUSTS WILL EXIST ON AN ISOLATED
BASIS GIVEN DCAPE VALUES AOA 900 J/KG. HOWEVER...THE LACK OF
STRONGER VERTICAL SHEAR / FORCING WILL LARGELY PREVENT CONVECTION
FROM EXHIBITING MORE ORGANIZED ATTRIBUTES OR PERSISTENCE. STORMS
WILL LIKELY WEAKEN AFTER 00Z AS DIABATIC HEATING WANES.

..COHEN.. 08/13/2011

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

ATTN...WFO...RAH...ILM...RNK...CHS...CAE...GSP...MRX...FFC...

LAT...LON   34967982 33758005 32778099 32548216 33128355 34818326
            35618217 36428165 37258130 37868041 37797951 36777912
            34967982

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 13, 1:33 PM EDT	Mesoscale Discussion	SPC	Beaufort, Bertie, Camden, Carteret, Chowan, Craven and 31 more	117 min
Aug 13, 2:07 PM EDT	Mesoscale Discussion	SPC	Arlington, Clarke, Culpeper, Fairfax, Fauquier, Frederick and 18 more	113 min

Nearby

Mesoscale Discussions in North Carolina, 2011 Mesoscale Discussions in South Carolina, 2011 Mesoscale Discussions in Georgia, 2011 Every mesoscale discussion in 2011

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.