Alert archive / Virginia / Tornado Watches in 2008

Tornado Watch 934

November 15, 20085 states

The Storm Prediction Center issued this tornado watch at Nov 15, 2008, 12:22 PM EST for 5 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Nov 15, 2008, 12:22 PM EST (17:22 UTC)
Expired
Nov 15, 2008, 7:00 PM EST
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 116 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Anne Arundel County, MD, Baltimore County, MD, Calvert County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, Charles County, MD, City of Baltimore, MD, Dorchester County, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Saint Mary's County, MD, Somerset County, MD, Talbot County, MD, Wicomico County, MD, Worcester County, MD, Atlantic County, NJ, Burlington County, NJ, Camden County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Mercer County, NJ, Monmouth County, NJ, Ocean County, NJ, Salem County, NJ, Adams County, PA, Berks County, PA, Bucks County, PA, Chester County, PA, Dauphin County, PA, Delaware County, PA, Lancaster County, PA, Lebanon County, PA, Montgomery County, PA, Philadelphia County, PA, York County, PA, Accomack County, VA, Amelia County, VA, Arlington County, VA, Brunswick County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Emporia, VA, City of Fairfax, VA, City of Falls Church, VA, City of Franklin, VA, City of Fredericksburg, VA, City of Hampton, VA, City of Hopewell, VA, City of Manassas, VA, City of Manassas Park, VA, City of Newport News, VA, City of Norfolk, VA, City of Petersburg, VA, City of Poquoson, VA, City of Portsmouth, VA, City of Richmond, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Williamsburg, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Gloucester County, VA, Goochland County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Isle of Wight County, VA, James City County, VA, King and Queen County, VA, King George County, VA, King William County, VA, Lancaster County, VA, Loudoun County, VA, Louisa County, VA, Lunenburg County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Richmond County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Westmoreland County, VA, York County, VA

The radar

The Sterling radar (KLWX), 83 km from the middle of the area, began a volume at 17:21 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
50%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
10%
One or more hailstones of 2 inches or more
5%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Nov 15, 1:37 PM ESTSevere Thunderstorm WarningRNKCampbell, Charlotte, Halifax, Pittsylvania38 min
Nov 15, 3:54 PM ESTSevere Thunderstorm WarningPHIBerks38 min
Nov 15, 4:15 PM ESTSevere Thunderstorm WarningPHINew Castle30 min
Nov 15, 4:15 PM ESTSevere Thunderstorm WarningPHIBerks, Bucks, Chester, Lehigh, Montgomery60 min
Nov 15, 4:18 PM ESTSevere Thunderstorm WarningPHIQueen Anne's27 min
Nov 15, 5:38 PM ESTSevere Thunderstorm WarningPHIKent, Sussex67 min
Nov 15, 5:55 PM ESTSevere Thunderstorm WarningPHIAtlantic, Cape May, Cumberland50 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

Washington/Dulle, VA (KIAD), launched 12:00Z, 5.4 hours before the alert went out and 75 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.

Skew-T log-pSkew-T log-p diagram, Washington/Dulle, VA at 12:00Z on 2008-11-15Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 13 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Washington/Dulle, VA at 12:00Z on 2008-11-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 330 square meters per square second.1939587897117Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
13 J/kg
Mixed-layer CIN
-110 J/kg
Mixed-layer LCL
443 m above ground
0-6 km bulk shear
77 kt
0-1 km storm-relative helicity
330 m²/s²
0-3 km storm-relative helicity
430 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000
WWUS20 KWNS 151724
SEL4  
SPC WW 151724
DCZ000-DEZ000-MDZ000-NJZ000-PAZ000-VAZ000-CWZ000-160000-

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 934
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM EST SAT NOV 15 2008

THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF 

       DISTRICT OF COLUMBIA
       DELAWARE
       MUCH OF MARYLAND
       ALL BUT NORTHERN NEW JERSEY
       PARTS OF SOUTHEASTERN PENNSYLVANIA
       MUCH OF EASTERN VIRGINIA
       COASTAL WATERS

EFFECTIVE THIS SATURDAY AFTERNOON AND EVENING FROM 1225 PM UNTIL
700 PM EST.

TORNADOES...HAIL TO 1 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 80 STATUTE
MILES EAST AND WEST OF A LINE FROM 25 MILES WEST NORTHWEST OF
TRENTON NEW JERSEY TO 20 MILES EAST SOUTHEAST OF SOUTH HILL
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.

DISCUSSION...VERY STRONG UPPER TROUGH AND ASSOCIATED WIND FIELDS
APPROACHING MID ATLANTIC STATES WHERE AIR MASS HAS CONTINUED TO WARM
AND DESTABILIZE THIS AM.  THUNDERSTORMS EXPECTED TO DEVELOP
ALONG/AHEAD OF COLD FRONT NOW MOVING E OF APPALACHIANS IN THE FORM
OF A SQUALL LINE.  IN ADDITION TO WIND DAMAGE...EMBEDDED SUPERCELLS
ARE POSSIBLE WITH TORNADO POTENTIAL.  ACTIVITY EXPECTED TO SPREAD
NEWD ACROSS THE WATCH AREA DURING THE AFTERNOON.

AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 1 INCH. EXTREME TURBULENCE AND SURFACE WIND
GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450.
MEAN STORM MOTION VECTOR 23045.


...HALES

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Nov 15, 11:07 AM ESTMesoscale DiscussionSPCKent, Sussex53 min
Nov 15, 6:15 PM ESTMesoscale DiscussionSPCKent, Sussex2 hr
Nov 15, 1:47 PM ESTMesoscale DiscussionSPCBergen, Essex, Hudson, Hunterdon, Morris, Passaic and 4 more58 min
Nov 15, 2:56 PM ESTTornado WatchSPCBergen, Essex, Hudson, Hunterdon, Middlesex, Morris and 5 more6 hr
Nov 15, 12:24 AM ESTTornado WatchSPCGreensville, Isle of Wight, Southampton, Surry, Sussex, York and 11 more9 hr
Nov 15, 3:10 AM ESTMesoscale DiscussionSPCBrunswick, Charles City, Dinwiddie, Gloucester, Greensville, Henrico and 26 more95 min
Nov 15, 4:10 AM ESTMesoscale DiscussionSPCCharles City, Gloucester, Greensville, Henrico, Isle of Wight, James City and 26 more65 min
Nov 15, 7:09 AM ESTMesoscale DiscussionSPCCity of Chesapeake, City of Franklin, City of Norfolk, City of Portsmouth, City of Suffolk, City of Virginia Beach66 min

Nearby

Tornado Watches in Virginia, 2008Tornado Watches in Maryland, 2008Tornado Watches in Pennsylvania, 2008Every tornado watch in 2008

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.