Alert archive / Virginia / Tornado Watches in 2011
Tornado Watch 233
The Storm Prediction Center issued this tornado watch at Apr 27, 2011, 1:23 PM EDT for 4 states. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2011, 1:23 PM EDT (17:23 UTC)
- Expired
- Apr 27, 2011, 6:19 PM EDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 127 counties
Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Saint Mary's County, MD, Washington County, MD, Alamance County, NC, Anson County, NC, Caswell County, NC, Chatham County, NC, Cumberland County, NC, Davidson County, NC, Durham County, NC, Edgecombe County, NC, Forsyth County, NC, Franklin County, NC, Granville County, NC, Guilford County, NC, Halifax County, NC, Harnett County, NC, Hoke County, NC, Johnston County, NC, Lee County, NC, Montgomery County, NC, Moore County, NC, Nash County, NC, Orange County, NC, Person County, NC, Randolph County, NC, Richmond County, NC, Rockingham County, NC, Sampson County, NC, Scotland County, NC, Stanly County, NC, Stokes County, NC, Vance County, NC, Wake County, NC, Warren County, NC, Wayne County, NC, Wilson County, NC, Albemarle County, VA, Alleghany County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, 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 Fredericksburg, 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 Richmond, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Franklin County, VA, Frederick County, VA, Goochland County, VA, Greene County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Madison County, VA, Mecklenburg County, VA, Nelson County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince William County, VA, Rappahannock County, VA, Rockbridge County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Grant County, WV, Hampshire County, WV, Hardy County, WV, Jefferson County, WV, Mineral County, WV, Morgan County, WV, Pendleton County, WV
The radar
The Roanoke radar (KFCX), 150 km from the middle of the area, began a volume at 17:26 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
30 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 1:27 PM EDT | Severe Thunderstorm Warning | RNK | Rockingham, Stokes, Surry, Yadkin | 63 min |
| Apr 27, 1:36 PM EDT | Severe Thunderstorm Warning | RAH | Durham, Granville, Person, Vance, Warren | 54 min |
| Apr 27, 1:41 PM EDT | Severe Thunderstorm Warning | RAH | Durham, Franklin, Granville, Vance, Wake, Warren | 64 min |
| Apr 27, 1:48 PM EDT | Severe Thunderstorm Warning | RAH | Davidson, Forsyth, Guilford | 57 min |
| Apr 27, 2:01 PM EDT | Severe Thunderstorm Warning | RAH | Edgecombe, Halifax, Nash | 59 min |
| Apr 27, 2:07 PM EDT | Severe Thunderstorm Warning | RNK | Bedford, Franklin, Henry, Pittsylvania, City of Martinsville | 38 min |
| Apr 27, 2:12 PM EDT | Severe Thunderstorm Warning | RAH | Edgecombe, Halifax, Nash, Wayne, Wilson | 42 min |
| Apr 27, 3:01 PM EDT | Severe Thunderstorm Warning | LWX | Albemarle, Nelson | 44 min |
| Apr 27, 3:43 PM EDT | Severe Thunderstorm Warning | LWX | Albemarle, Orange | 47 min |
| Apr 27, 3:54 PM EDT | Severe Thunderstorm Warning | AKQ | Fluvanna, Louisa | 36 min |
| Apr 27, 4:44 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Orange, Spotsylvania | 46 min |
| Apr 27, 4:56 PM EDT | Severe Thunderstorm Warning | RNK | Bedford, Franklin, Henry, Pittsylvania | 49 min |
| Apr 27, 5:08 PM EDT | Tornado Warning | LWX | Orange, Spotsylvania | 37 min |
| Apr 27, 5:22 PM EDT | Severe Thunderstorm Warning | RNK | Rockingham, Stokes | 53 min |
| Apr 27, 5:24 PM EDT | Severe Thunderstorm Warning | RNK | Buckingham, Charlotte | 35 min |
| Apr 27, 5:30 PM EDT | Severe Thunderstorm Warning | LWX | Culpeper, Fauquier, Orange, Spotsylvania, Stafford | 45 min |
| Apr 27, 5:43 PM EDT | Severe Thunderstorm Warning | RAH | Davidson, Forsyth, Guilford, Randolph | 62 min |
| Apr 27, 5:46 PM EDT | Tornado Warning | LWX | Charles | 29 min |
| Apr 27, 5:46 PM EDT | Severe Thunderstorm Warning | AKQ | Amelia, Cumberland, Powhatan, Prince Edward | 44 min |
| Apr 27, 5:46 PM EDT | Severe Thunderstorm Warning | RNK | Charlotte, Halifax | 34 min |
| Apr 27, 5:53 PM EDT | Severe Thunderstorm Warning | RNK | Amherst, Appomattox, Campbell, City of Lynchburg | 37 min |
| Apr 27, 6:05 PM EDT | Severe Thunderstorm Warning | RNK | Rockingham, Stokes | 40 min |
| Apr 27, 6:06 PM EDT | Severe Thunderstorm Warning | RAH | Durham, Granville, Orange, Person | 32 min |
| Apr 27, 6:07 PM EDT | Tornado Warning | RNK | Rockingham, Stokes | 23 min |
| Apr 27, 6:08 PM EDT | Tornado Warning | LWX | Charles | 37 min |
| Apr 27, 6:09 PM EDT | Tornado Warning | RNK | Rockingham | 36 min |
| Apr 27, 6:15 PM EDT | Tornado Warning | AKQ | Amelia, Cumberland, Powhatan, Prince Edward | 45 min |
| Apr 27, 6:17 PM EDT | Tornado Warning | RAH | Forsyth | 43 min |
| Apr 27, 6:17 PM EDT | Severe Thunderstorm Warning | LWX | Fairfax, Prince William | 43 min |
| Apr 27, 6:19 PM EDT | Tornado Warning | RAH | Davidson, Forsyth, Guilford | 41 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Roanoke, VA (KRNK), launched 12:00Z, 5.4 hours before the alert went out and 85 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
- 190 J/kg
- Mixed-layer CIN
- -25 J/kg
- Mixed-layer LCL
- 678 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 203 m²/s²
- 0-3 km storm-relative helicity
- 275 m²/s²
- Significant tornado parameter
- 0.1
- Supercell composite
- 1.3
The text
As transmitted, in the capitals the NWS used until 2016.
713
WWUS20 KWNS 271722
SEL3
SPC WW 271722
MDZ000-NCZ000-VAZ000-WVZ000-CWZ000-280000-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 233
NWS STORM PREDICTION CENTER NORMAN OK
125 PM EDT WED APR 27 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
CENTRAL MARYLAND
CENTRAL NORTH CAROLINA
CENTRAL VIRGINIA
EASTERN WEST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS WEDNESDAY AFTERNOON AND EVENING FROM 125 PM UNTIL
800 PM EDT.
TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 60 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH NORTHWEST OF
MARTINSBURG WEST VIRGINIA TO 25 MILES SOUTH OF SOUTHERN PINES
NORTH CAROLINA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
OTHER WATCH INFORMATION...CONTINUE...WW 230...WW 231...WW 232...
DISCUSSION...SCATTERED THUNDERSTORMS ARE INCREASING ACROSS PORTIONS
OF NC/VA IN REGION OF WARM/MOIST AND UNSTABLE AIR MASS. INCREASING
MID AND LOW LEVEL WIND FIELDS THROUGH THE DAY SUGGEST A RISK OF
ORGANIZED/SUPERCELL STORMS CAPABLE OF LARGE HAIL AND DAMAGING WINDS.
THE TORNADO THREAT IS NOT PARTICULARLY HIGH...BUT SUFFICIENT LOW
LEVEL SHEAR IS PRESENT FOR A RISK OF ISOLATED SPIN UPS IN THE MOST
INTENSE SUPERCELLS.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 22035.
...HARTSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 1:24 PM EDT | Mesoscale Discussion | SPC | Allegany, Garrett | 96 min |
| Apr 27, 3:10 PM EDT | Tornado Watch | SPC | Garrett | 7 hr |
| Apr 27, 3:55 PM EDT | Mesoscale Discussion | SPC | Caroline, Cecil, Dorchester, Harford, Kent, Queen Anne's and 3 more | 65 min |
| Apr 27, 4:39 PM EDT | Mesoscale Discussion | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 10 more | 66 min |
| Apr 27, 6:00 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Carroll, Charles, Frederick and 9 more | 60 min |
| Apr 27, 6:15 PM EDT | Tornado Watch | SPC | Allegany, Anne Arundel, Baltimore, Calvert, Carroll, Charles and 8 more | 6 hr |
| Apr 27, 6:50 PM EDT | Mesoscale Discussion | SPC | Carroll, Harford, Washington | 55 min |
| Apr 27, 7:55 PM EDT | Mesoscale Discussion | SPC | Anne Arundel, Baltimore, Calvert, Carroll, Charles, Harford and 8 more | 65 min |
| Apr 27, 8:34 AM EDT | Tornado Watch | SPC | Cherokee, Clay | 4 hr |
| Apr 27, 11:27 AM EDT | Tornado Watch | SPC | Cherokee, Clay | 6 hr |
| Apr 27, 12:39 PM EDT | Mesoscale Discussion | SPC | Cherokee | 66 min |
| Apr 27, 12:51 PM EDT | Mesoscale Discussion | SPC | Alamance, Anson, Bertie, Bladen, Cabarrus, Caswell and 47 more | 84 min |
| Apr 27, 2:03 PM EDT | Mesoscale Discussion | SPC | Cherokee, Clay, Graham | 57 min |
| Apr 27, 3:22 PM EDT | Mesoscale Discussion | SPC | Alleghany, Ashe, Avery, Buncombe, Caldwell, Haywood and 6 more | 83 min |
| Apr 27, 4:36 PM EDT | Tornado Watch | SPC | Cherokee, Clay | 8 hr |
| Apr 27, 6:41 PM EDT | Mesoscale Discussion | SPC | Alexander, Avery, Buncombe, Burke, Caldwell, Catawba and 16 more | 34 min |
| Apr 27, 6:52 PM EDT | Tornado Watch | SPC | Alexander, Avery, Buncombe, Burke, Caldwell, Catawba and 19 more | 9 hr |
| Apr 27, 5:38 PM EDT | Mesoscale Discussion | SPC | Buchanan, Dickenson, Lee, Russell, Scott, Wise and 1 more | 37 min |
| Apr 27, 5:44 PM EDT | Tornado Watch | SPC | Buchanan, Dickenson, Lee, Russell, Scott, Smyth and 5 more | 7 hr |
| Apr 27, 9:39 AM EDT | Mesoscale Discussion | SPC | Cabell, Calhoun, Jackson, Kanawha, Lincoln, Mason and 7 more | 66 min |
Nearby
Tornado Watches in Virginia, 2011Tornado Watches in North Carolina, 2011Tornado Watches in Maryland, 2011Every tornado watch 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.