Alert archive / Virginia / Mesoscale Discussions in 2011
Mesoscale Discussion 649
The Storm Prediction Center issued this mesoscale discussion at Apr 28, 2011, 12:27 AM EDT for 4 states. It was in force for 63 min.
The area
The outline as issued.
The facts
- Issued
- Apr 28, 2011, 12:27 AM EDT (04:27 UTC)
- Expired
- Apr 28, 2011, 1:30 AM EDT
- In force
- 63 min
- Issued by
- the Storm Prediction Center
All 108 counties
Allegany County, MD, Frederick County, MD, Howard County, MD, Montgomery County, MD, Washington County, MD, Alamance County, NC, Alleghany County, NC, Ashe County, NC, Caswell County, NC, Davidson County, NC, Davie County, NC, Forsyth County, NC, Guilford County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Watauga County, NC, Wilkes County, NC, Yadkin County, NC, Albemarle County, VA, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Bland County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Charlottesville, VA, City of Covington, VA, City of Danville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Galax, VA, City of Harrisonburg, VA, City of Lexington, VA, City of Lynchburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Martinsville, VA, City of Radford, VA, City of Roanoke, VA, City of Salem, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Craig County, VA, Culpeper County, VA, Cumberland County, VA, Fairfax County, VA, Fauquier County, VA, Floyd County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Giles County, VA, Goochland County, VA, Grayson County, VA, Greene County, VA, Halifax County, VA, Henry County, VA, Highland County, VA, Loudoun County, VA, Louisa County, VA, Madison County, VA, Montgomery County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Patrick County, VA, Pittsylvania County, VA, Prince Edward County, VA, Prince William County, VA, Pulaski County, VA, Rappahannock County, VA, Roanoke County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Wythe County, VA, Berkeley County, WV, Grant County, WV, Greenbrier County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mercer County, WV, Mineral County, WV, Monroe County, WV, Morgan County, WV, Pendleton County, WV, Pocahontas County, WV, Randolph County, WV, Summers County, WV, Tucker County, WV
The radar
The Sterling radar (KLWX), 151 km from the middle of the area, began a volume at 04:28 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
Roanoke, VA (KRNK), launched 00:00Z, 4.5 hours before the alert went out and 114 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
- 372 J/kg
- Mixed-layer CIN
- -24 J/kg
- Mixed-layer LCL
- 1272 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 226 m²/s²
- 0-3 km storm-relative helicity
- 335 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 3.0
The text
As transmitted, in the capitals the NWS used until 2016.
624
ACUS11 KWNS 280427
SWOMCD
SPC MCD 280427
MDZ000-DCZ000-VAZ000-WVZ000-NCZ000-280530-
MESOSCALE DISCUSSION 0649
NWS STORM PREDICTION CENTER NORMAN OK
1127 PM CDT WED APR 27 2011
AREAS AFFECTED...WRN/CNTRL VA...ERN WV...WRN MD...NWRN NC
CONCERNING...TORNADO WATCH 240...
VALID 280427Z - 280530Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 240 CONTINUES.
TORNADO WATCH 240 IS SCHEDULED TO EXPIRE AT 06Z AND WILL BE
REDEFINED SOON WITH A REPLACEMENT WW.
NUMEROUS ROTATING STORMS PERSIST WITHIN A LARGER CONVECTIVE COMPLEX
ACROSS THE CNTRL APPALACHIANS FROM THE MD PANHANDLE ACROSS ERN WV
INTO SWRN VA. LATEST OBJECTIVE ANALYSIS INDICATES DOWNSTREAM AIR
MASS REMAINS MODERATELY UNSTABLE WITH UPPER 60S TO LOWER 70S SURFACE
DEW POINTS COMMON ACROSS THE PIEDMONT. GIVEN PRESENCE OF EXTREME
LOW-LEVEL SHEAR...0-1 KM SRH AROUND 500 M2/S2 SAMPLED BY LWX/FCX VWP
DATA...ATTENDANT THREATS FOR TORNADOES AND DAMAGING WINDS/LARGE HAIL
WILL LIKELY PERSIST BEYOND 06Z WW EXPIRATION.
..GRAMS.. 04/28/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...AKQ...LWX...RAH...RNK...PBZ...RLX...GSP...
LAT...LON 38477738 35937907 35457995 36168176 37678099 39597910
39717770 39517700 39197686 38477738SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 8:15 PM EDT | Severe Thunderstorm Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 8 hr |
| Apr 28, 12:41 AM EDT | Tornado Watch | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 8 more | 7 hr |
| Apr 28, 4:05 AM EDT | Severe Thunderstorm Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 6 hr |
| Apr 28, 7:38 AM EDT | Tornado Watch | SPC | Anne Arundel, Baltimore, Calvert, Carroll, Charles, Dorchester and 10 more | 7 hr |
| Apr 28, 9:45 AM EDT | Severe Thunderstorm Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 6 hr |
| Apr 28, 10:44 AM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Caroline, Carroll, Cecil and 13 more | 61 min |
| Apr 28, 11:49 AM EDT | Mesoscale Discussion | SPC | Cecil, Kent, Queen Anne's | 56 min |
| Apr 28, 2:00 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Calvert, Caroline, Charles, Dorchester, Kent and 7 more | 60 min |
| Apr 28, 2:41 PM EDT | Tornado Watch | SPC | Dorchester, Somerset, Wicomico, Worcester | 6 hr |
| Apr 28, 6:33 PM EDT | Mesoscale Discussion | SPC | Dorchester, Saint Mary's, Somerset, Wicomico, Worcester | 57 min |
| Apr 27, 10:12 PM EDT | Mesoscale Discussion | SPC | Alleghany, Ashe, Forsyth, Rockingham, Stokes, Surry and 3 more | 63 min |
| Apr 28, 12:09 AM EDT | Mesoscale Discussion | SPC | Alexander, Alleghany, Ashe, Avery, Buncombe, Burke and 25 more | 36 min |
| Apr 28, 12:56 AM EDT | Tornado Watch | SPC | Alexander, Avery, Buncombe, Burke, Cabarrus, Caldwell and 21 more | 4 hr |
| Apr 28, 3:30 AM EDT | Mesoscale Discussion | SPC | Alexander, Anson, Burke, Cabarrus, Catawba, Cleveland and 10 more | 90 min |
| Apr 28, 4:30 AM EDT | Tornado Watch | SPC | Alamance, Anson, Bladen, Chatham, Cumberland, Davidson and 27 more | 10 hr |
| Apr 28, 8:05 AM EDT | Mesoscale Discussion | SPC | Anson, Chatham, Cumberland, Durham, Edgecombe, Franklin and 15 more | 85 min |
| Apr 28, 8:48 AM EDT | Tornado Watch | SPC | Beaufort, Bladen, Brunswick, Carteret, Columbus, Craven and 15 more | 7 hr |
| Apr 28, 11:22 AM EDT | Mesoscale Discussion | SPC | Beaufort, Bertie, Bladen, Brunswick, Chowan, Columbus and 29 more | 53 min |
| Apr 28, 3:19 PM EDT | Tornado Watch | SPC | Bladen, Brunswick, Columbus, New Hanover, Pender | 4 hr |
| Apr 27, 9:22 PM EDT | Mesoscale Discussion | SPC | Buchanan, Dickenson, Lee, Russell, Scott, Smyth and 5 more | 53 min |
| Apr 28, 12:34 AM EDT | Mesoscale Discussion | SPC | Buchanan, Dickenson, Lee, Russell, Scott, Tazewell and 3 more | 26 min |
Nearby
Mesoscale Discussions in Virginia, 2011Mesoscale Discussions in North Carolina, 2011Mesoscale Discussions in West Virginia, 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.