Alert archive / Virginia / Tornado Watches in 2011
Tornado Watch 810
The Storm Prediction Center issued this tornado watch at Aug 27, 2011, 12:32 AM EDT for Somerset County, Wicomico County, Worcester County, Maryland; 20 counties in North Carolina; 21 counties in Virginia. It was in force for 10 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 27, 2011, 12:32 AM EDT (04:32 UTC)
- Expired
- Aug 27, 2011, 11:00 AM EDT
- In force
- 10 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 60 kt
All 44 counties
Somerset County, MD, Wicomico County, MD, Worcester County, MD, Beaufort County, NC, Bertie County, NC, Camden County, NC, Carteret County, NC, Chowan County, NC, Craven County, NC, Currituck County, NC, Dare County, NC, Gates County, NC, Hertford County, NC, Hyde County, NC, Jones County, NC, Martin County, NC, Northampton County, NC, Onslow County, NC, Pamlico County, NC, Pasquotank County, NC, Perquimans County, NC, Tyrrell County, NC, Washington County, NC, Accomack County, VA, City of Chesapeake, VA, City of Franklin, VA, City of Hampton, VA, City of Newport News, VA, City of Norfolk, VA, City of Portsmouth, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Gloucester County, VA, Isle of Wight County, VA, James City County, VA, Lancaster County, VA, Mathews County, VA, Middlesex County, VA, Northampton County, VA, Northumberland County, VA, Southampton County, VA, Surry County, VA, York County, VA
The radar
The Norfolk radar (KAKQ), 84 km from the middle of the area, began a volume at 04:36 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
- 80%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 10%
- One or more gusts of 65 knots or more
- 5%
- 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
- 20%
Warnings issued inside it
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 2:19 AM EDT | Tornado Warning | AKQ | Chowan, Perquimans | 26 min |
| Aug 27, 2:20 AM EDT | Tornado Warning | AKQ | Camden, Currituck | 25 min |
| Aug 27, 2:45 AM EDT | Tornado Warning | AKQ | Bertie, Chowan, Pasquotank, Perquimans | 30 min |
| Aug 27, 3:11 AM EDT | Tornado Warning | AKQ | Camden, Chowan, Gates, Pasquotank, Perquimans | 19 min |
| Aug 27, 3:11 AM EDT | Tornado Warning | AKQ | Bertie, Chowan, Hertford | 34 min |
| Aug 27, 3:37 AM EDT | Tornado Warning | AKQ | Camden, Currituck | 23 min |
| Aug 27, 4:34 AM EDT | Tornado Warning | AKQ | City of Chesapeake, City of Virginia Beach | 26 min |
| Aug 27, 6:21 AM EDT | Tornado Warning | AKQ | Gates | 13 min |
| Aug 27, 8:25 AM EDT | Tornado Warning | AKQ | City of Chesapeake, City of Virginia Beach | 35 min |
| Aug 27, 8:47 AM EDT | Tornado Warning | AKQ | City of Chesapeake, City of Norfolk, City of Portsmouth, City of Virginia Beach | 43 min |
| Aug 27, 10:44 AM EDT | Tornado Warning | AKQ | City of Chesapeake, City of Norfolk, City of Portsmouth, City of Virginia Beach | 31 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
Wallops Is Stn, VA (KWAL), launched 00:00Z, 4.5 hours before the alert went out and 136 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
- 901 J/kg
- Mixed-layer CIN
- -12 J/kg
- Mixed-layer LCL
- 737 m above ground
- 0-6 km bulk shear
- 6 kt
- 0-1 km storm-relative helicity
- -14 m²/s²
- 0-3 km storm-relative helicity
- 8 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
242
WWUS20 KWNS 270438
SEL0
SPC WW 270438
MDZ000-NCZ000-VAZ000-CWZ000-271500-
URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 810
NWS STORM PREDICTION CENTER NORMAN OK
1225 AM EDT SAT AUG 27 2011
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
THE LOWER EASTERN SHORE OF MARYLAND
FAR EASTERN NORTH CAROLINA
SOUTHEAST VIRGINIA
COASTAL WATERS
EFFECTIVE THIS SATURDAY MORNING FROM 1225 AM UNTIL 1100 AM EDT.
TORNADOES...HAIL TO 0.5 INCH IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 50 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES NORTH OF WALLOPS
VIRGINIA TO 40 MILES SOUTHEAST OF NEW BERN NORTH CAROLINA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU0).
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 809...
DISCUSSION...SHOWERS AND SCTD TSTMS EXPECTED TO PERSIST IN A W-E ARC
OF LOW LVL CONFLUENCE MOVING NWD ACROSS NE NC AND THE ADJACENT CSTL
WATERS ON NRN SIDE OF IMMEDIATE CIRCULATION OF HRCN IRENE. FARTHER
N...A SEPARATE BAND OF MORE INTERMITTENT ACTIVITY MAY PERSIST AND
MOVE NWD FROM OFF THE MOUTH OF CHESAPEAKE BAY.
INCREASING LOW TO MID LVL WIND FIELD WITH THE CONTINUED NWD MOVEMENT
OF IRENE...AND CONTINUED LOW LVL THETA-E ADVECTION AHEAD OF
STORM...WILL CREATE AN ENVIRONMENT INCREASINGLY FAVORABLE FOR LOW
LVL ROTATION/POSSIBLE TORNADOES NWD INTO TIDEWATER VA AND THE LWR
ERN SHORE OF MARYLAND THROUGH MID/LATE MORNING SATURDAY...WHILE
EXISTING THREAT PERSISTS OVER E CNTRL AND NE NC.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 0.5 INCH. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 12045.
...CORFIDISPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 3:06 AM EDT | Mesoscale Discussion | SPC | Somerset, Wicomico, Worcester | 114 min |
| Aug 27, 7:52 AM EDT | Mesoscale Discussion | SPC | Somerset, Wicomico, Worcester | 113 min |
| Aug 27, 10:31 AM EDT | Mesoscale Discussion | SPC | Somerset, Wicomico, Worcester | 29 min |
| Aug 27, 10:41 AM EDT | Tornado Watch | SPC | Calvert, Caroline, Dorchester, Kent, Queen Anne's, Saint Mary's and 4 more | 9 hr |
| Aug 27, 1:01 PM EDT | Mesoscale Discussion | SPC | Calvert, Caroline, Dorchester, Kent, Queen Anne's, Saint Mary's and 4 more | 119 min |
| Aug 27, 4:44 PM EDT | Mesoscale Discussion | SPC | Somerset, Wicomico, Worcester | 2 hr |
| Aug 27, 7:56 PM EDT | Tornado Watch | SPC | Caroline, Cecil, Kent, Queen Anne's, Talbot | 9 hr |
| Aug 26, 8:11 PM EDT | Tornado Watch | SPC | Beaufort, Brunswick, Carteret, Craven, Dare, Hyde and 6 more | 9 hr |
| Aug 26, 11:06 PM EDT | Mesoscale Discussion | SPC | Beaufort, Bertie, Bladen, Brunswick, Camden, Carteret and 36 more | 84 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.