Alert archive / Virginia / Tornado Watches in 2011
Tornado Watch 844
The Storm Prediction Center issued this tornado watch at Sep 5, 2011, 6:29 PM EDT for 12 counties in North Carolina; 33 counties in Virginia. It was in force for 10 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 5, 2011, 6:29 PM EDT (22:29 UTC)
- Expired
- Sep 6, 2011, 4:00 AM EDT
- In force
- 10 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 65 kt
All 45 counties
Alamance County, NC, Alleghany County, NC, Caswell County, NC, Davidson County, NC, Forsyth County, NC, Guilford County, NC, Randolph County, NC, Rockingham County, NC, Stokes County, NC, Surry County, NC, Wilkes County, NC, Yadkin County, NC, Alleghany County, VA, Amherst County, VA, Appomattox County, VA, Bath County, VA, Bedford County, VA, Botetourt County, VA, Buckingham County, VA, Campbell County, VA, Carroll County, VA, Charlotte County, VA, City of Buena Vista, VA, City of Covington, 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, Craig County, VA, Cumberland County, VA, Floyd County, VA, Franklin County, VA, Halifax County, VA, Henry County, VA, Montgomery County, VA, Patrick County, VA, Pittsylvania County, VA, Prince Edward County, VA, Pulaski County, VA, Roanoke County, VA, Rockbridge County, VA
The radar
The Roanoke radar (KFCX), 45 km from the middle of the area, began a volume at 22:28 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 50%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 50%
Warnings issued inside it
19 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 5, 6:42 PM EDT | Tornado Warning | RNK | Halifax | 33 min |
| Sep 5, 6:54 PM EDT | Tornado Warning | RNK | Carroll, Floyd, Patrick | 36 min |
| Sep 5, 7:14 PM EDT | Tornado Warning | RNK | Bland, Pulaski, Wythe | 31 min |
| Sep 5, 7:16 PM EDT | Tornado Warning | RNK | Charlotte, Halifax | 29 min |
| Sep 5, 7:40 PM EDT | Tornado Warning | RNK | Bland, Giles, Montgomery, Pulaski, Wythe, City of Radford | 35 min |
| Sep 5, 8:12 PM EDT | Tornado Warning | RNK | Craig, Giles, Montgomery, Roanoke | 33 min |
| Sep 5, 8:36 PM EDT | Tornado Warning | RNK | Bedford | 39 min |
| Sep 5, 8:44 PM EDT | Flash Flood Warning | RNK | Watauga, Wilkes | 6 hr |
| Sep 5, 9:13 PM EDT | Severe Thunderstorm Warning | RNK | Wilkes | 47 min |
| Sep 5, 9:40 PM EDT | Severe Thunderstorm Warning | RNK | Stokes, Surry, Wilkes, Yadkin | 45 min |
| Sep 5, 10:03 PM EDT | Tornado Warning | RNK | Carroll, Patrick | 27 min |
| Sep 5, 10:09 PM EDT | Flash Flood Warning | RNK | Floyd, Franklin, Roanoke | 6 hr |
| Sep 5, 10:19 PM EDT | Flash Flood Warning | RNK | Surry | 6 hr |
| Sep 5, 10:50 PM EDT | Severe Thunderstorm Warning | RNK | Buckingham | 25 min |
| Sep 5, 10:52 PM EDT | Flash Flood Warning | RNK | Bedford, Campbell, Franklin, City of Lynchburg | 6 hr |
| Sep 5, 11:04 PM EDT | Flash Flood Warning | RNK | Carroll, Floyd, Franklin, Patrick | 6 hr |
| Sep 5, 11:22 PM EDT | Flash Flood Warning | RNK | Amherst | 6 hr |
| Sep 6, 12:17 AM EDT | Flash Flood Warning | RNK | Alleghany, Surry, Wilkes | 6 hr |
| Sep 6, 1:10 AM EDT | Severe Thunderstorm Warning | RNK | Appomattox, Buckingham | 65 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
Greensboro/Hi Pt, NC (KGSO), launched 12:00Z, 10.5 hours before the alert went out and 67 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
- 109 J/kg
- Mixed-layer CIN
- -38 J/kg
- Mixed-layer LCL
- 689 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 62 m²/s²
- 0-3 km storm-relative helicity
- 48 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
164
WWUS20 KWNS 052232
SEL4
SPC WW 052232
NCZ000-VAZ000-060800-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 844
NWS STORM PREDICTION CENTER NORMAN OK
630 PM EDT MON SEP 5 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
NORTHWESTERN NORTH CAROLINA
SOUTH-CENTRAL THROUGH WEST-CENTRAL VIRGINIA
EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 630 PM UNTIL
400 AM EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 75 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 65 STATUTE
MILES EAST AND WEST OF A LINE FROM 20 MILES SOUTHWEST OF
GREENSBORO NORTH CAROLINA TO 35 MILES NORTH OF LYNCHBURG
VIRGINIA. FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU4).
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 840...WW 841...WW
842...WW 843...
DISCUSSION...TORNADIC SUPERCELL POTENTIAL...WITH FAVORABLE
JUXTAPOSITION OF LOW-LEVEL MOISTURE AND SHEAR...SHOULD SPREAD/SHIFT
NEWD ACROSS WW AREA THROUGH EVENING AND OVERNIGHT HOURS. INCREASE
IN LOW-LEVEL SHEAR AND SRH SHOULD OCCUR IN STEP WITH NEWD
TRANSLATION OF REMNANTS OF T.D. LEE ALONG QUASISTATIONARY LOW-LEVEL
BAROCLINIC ZONE. THAT FRONTAL ZONE EFFECTIVELY DEMARCATES WRN RIM
OF THREAT...AND OF WW...W OF WHICH INSTABILITY WILL DIMINISH
CONSIDERABLY.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 65 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
550. MEAN STORM MOTION VECTOR 22030.
...EDWARDSSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 5, 3:42 PM EDT | Tornado Watch | SPC | Alexander, Burke, Cabarrus, Caldwell, Catawba, Cleveland and 11 more | 7 hr |
| Sep 5, 5:48 PM EDT | Mesoscale Discussion | SPC | Bladen, Brunswick, Columbus, Craven, Cumberland, Duplin and 19 more | 87 min |
| Sep 5, 5:52 PM EDT | Mesoscale Discussion | SPC | Alamance, Alleghany, Ashe, Caswell, Chatham, Durham and 13 more | 53 min |
| Sep 5, 6:12 PM EDT | Severe Thunderstorm Watch | SPC | Anson, Cumberland, Harnett, Hoke, Lee, Montgomery and 5 more | 4 hr |
| Sep 5, 7:37 PM EDT | Mesoscale Discussion | SPC | Alamance, Alexander, Burke, Cabarrus, Caldwell, Caswell and 24 more | 113 min |
Nearby
Tornado Watches in Virginia, 2011Tornado Watches in North Carolina, 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.