Alert archive / North Carolina / Mesoscale Discussions in 2011
Mesoscale Discussion 2003
The Storm Prediction Center issued this mesoscale discussion at Aug 18, 2011, 2:59 PM EDT for 5 states. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 18, 2011, 2:59 PM EDT (18:59 UTC)
- Expired
- Aug 18, 2011, 5:00 PM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
All 86 counties
Habersham County, GA, Rabun County, GA, Towns County, GA, Union County, GA, White County, GA, Alexander County, NC, Alleghany County, NC, Ashe County, NC, Avery County, NC, Buncombe County, NC, Burke County, NC, Caldwell County, NC, Catawba County, NC, Cherokee County, NC, Clay County, NC, Cleveland County, NC, Davie County, NC, Forsyth 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, Mitchell County, NC, Polk County, NC, Rockingham County, NC, Rutherford County, NC, Stokes County, NC, Surry County, NC, Swain County, NC, Transylvania County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Yancey County, NC, Cherokee County, SC, Greenville County, SC, Oconee County, SC, Pickens County, SC, Spartanburg County, SC, Carter County, TN, Cocke County, TN, Greene County, TN, Johnson County, TN, Sevier County, TN, Sullivan County, TN, Unicoi County, TN, Washington County, TN, Albemarle County, VA, Amherst County, VA, Appomattox County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Danville, VA, City of Galax, VA, City of Lexington, VA, City of Lynchburg, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Waynesboro, VA, Craig County, VA, Floyd County, VA, Franklin County, VA, Grayson County, VA, Henry County, VA, Montgomery County, VA, Nelson County, VA, Patrick County, VA, Pittsylvania County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA, Smyth County, VA, Wythe County, VA
The radar
The Roanoke radar (KFCX), 136 km from the middle of the area, began a volume at 19:01 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, 7.0 hours before the alert went out and 147 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.
- Mixed-layer CAPE
- 257 J/kg
- Mixed-layer CIN
- -74 J/kg
- Mixed-layer LCL
- 1327 m above ground
- 0-6 km bulk shear
- 17 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- -9 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
608
ACUS11 KWNS 181859
SWOMCD
SPC MCD 181859
VAZ000-NCZ000-WVZ000-SCZ000-TNZ000-GAZ000-182100-
MESOSCALE DISCUSSION 2003
NWS STORM PREDICTION CENTER NORMAN OK
0159 PM CDT THU AUG 18 2011
AREAS AFFECTED...PORTIONS OF WRN VA...WRN NC...NWRN SC...FAR NERN
GA...FAR ERN TN
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 181859Z - 182100Z
WHILE A FEW STORMS COULD PRODUCE GUSTY WINDS...THE OVERALL SVR
THREAT WILL LIKELY REMAIN MINIMAL...THUS PRECLUDING THE NEED FOR A
WW.
ASCENT OFFERED BY A SUBTLE MID-LEVEL VORT MAX EMBEDDED WITHIN BROAD
CYCLONIC FLOW OVER THE MID-ATLANTIC STATES /PER RECENT WATER VAPOR
IMAGERY/ IS BEING AUGMENTED BY SFC CONVERGENCE ALONG A TROUGH LYING
IN THE LEE OF THE APPALACHIANS PER 18Z SFC MESOANALYSIS. THIS
ASCENT...FURTHER REINFORCED BY OROGRAPHIC FORCING AND JUXTAPOSED
WITH MLCAPE VALUES OF 1000-2000 J/KG PER MODIFICATIONS TO THE 12Z
BLACKSBURG VA RAOB TO ACCOUNT FOR CURRENT OBS...IS FOSTERING THE
DEVELOPMENT OF ISOLATED TO SCATTERED CONVECTION NEAR AND JUST EAST
OF THE BLUE RIDGE. CONVECTION COULD INCREASE IN NUMBER/INTENSITY
WHILE BEING STEERED EWD OVER ADJACENT SECTIONS OF THE PIEDMONT
REGION...WHERE DESTABILIZATION OWING TO AMPLE INSOLATION IS ONGOING.
FURTHERMORE...A VERY MODEST ENHANCEMENT TO THE MID-LEVEL FLOW IN
ASSOCIATION WITH THE VORT MAX IS GENERATING EFFECTIVE BULK SHEAR
MAGNITUDES OF 20-30 KT...PRIMARILY NEAR AND ADJACENT TO THE SRN
APPALACHIANS. THIS SHEAR COULD SUPPORT OCCASIONAL MULTICELL
CONVECTION...WITH WEAKER VERTICAL SHEAR ELSEWHERE MORE SUPPORTIVE OF
PULSE CONVECTION. GUSTY WINDS WILL BE THE MAIN CONCERN WITH THIS
ACTIVITY...AND AN ISOLATED INSTANCE OR TWO OF DMGG WIND GUSTS CANNOT
ENTIRELY BE RULED OUT. HOWEVER...THE LACK OF STRONGER FORCING /
VERTICAL SHEAR SHOULD LARGELY PREVENT CONVECTION FROM ACHIEVING ANY
SUBSTANTIAL ORGANIZATION AND MITIGATE THE SVR THREAT.
..COHEN.. 08/18/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...AKQ...LWX...RAH...RNK...GSP...MRX...FFC...
LAT...LON 36098315 36728195 37637997 38337858 37647827 36207964
34668213 34608398 35188428 36098315SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 18, 6:39 PM EDT | Mesoscale Discussion | SPC | Arlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church | 96 min |
Nearby
Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in Tennessee, 2011Every 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.