Alert archive / Virginia / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 418

June 22, 20124 states

The Storm Prediction Center issued this severe thunderstorm watch at Jun 22, 2012, 2:12 PM EDT for 4 states. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued: Jun 22, 2012, 2:12 PM EDT (18:12 UTC)
Expired: Jun 22, 2012, 9:00 PM EDT
In force: 7 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 65 kt

All 127 counties

Kent County, DE, New Castle County, DE, Sussex County, DE, Allegany County, MD, 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, Washington County, MD, Wicomico County, MD, Worcester County, MD, Atlantic County, NJ, Cape May County, NJ, Cumberland County, NJ, Gloucester County, NJ, Salem County, NJ, Accomack County, VA, Albemarle County, VA, Amelia County, VA, Amherst County, VA, Appomattox County, VA, Arlington County, VA, Augusta County, VA, Brunswick County, VA, Buckingham County, VA, Campbell County, VA, Caroline County, VA, Charles City County, VA, Charlotte County, VA, Chesterfield County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Chesapeake, VA, City of Colonial Heights, VA, City of Danville, 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 Harrisonburg, VA, City of Hopewell, VA, City of Lynchburg, VA, City of Manassas, VA, City of Martinsville, 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 Staunton, VA, City of Suffolk, VA, City of Virginia Beach, VA, City of Waynesboro, VA, City of Williamsburg, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Cumberland County, VA, Dinwiddie County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Fluvanna County, VA, Frederick County, VA, Gloucester County, VA, Goochland County, VA, Greene County, VA, Greensville County, VA, Halifax County, VA, Hanover County, VA, Henrico County, VA, Henry 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, Madison County, VA, Mathews County, VA, Mecklenburg County, VA, Middlesex County, VA, Nelson County, VA, New Kent County, VA, Northampton County, VA, Northumberland County, VA, Nottoway County, VA, Orange County, VA, Page County, VA, Pittsylvania County, VA, Powhatan County, VA, Prince Edward County, VA, Prince George County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockingham County, VA, Shenandoah County, VA, Southampton County, VA, Spotsylvania County, VA, Stafford County, VA, Surry County, VA, Sussex County, VA, Warren County, VA, Westmoreland County, VA, York County, VA

The radar

The Norfolk radar (KAKQ), 103 km from the middle of the area, began a volume at 18:14 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: 5%
One or more EF2 to EF5 tornadoes: 2%
Ten or more severe wind reports: 60%
One or more gusts of 65 knots or more: 30%
Ten or more severe hail reports: 20%
One or more hailstones of 2 inches or more: 10%
Six or more combined severe hail and wind reports: 80%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jun 22, 2:26 PM EDT	Severe Thunderstorm Warning	AKQ	Lancaster, Mathews, Middlesex	49 min
Jun 22, 2:38 PM EDT	Severe Thunderstorm Warning	RNK	Campbell, Charlotte, Halifax, Pittsylvania	67 min
Jun 22, 2:45 PM EDT	Severe Thunderstorm Warning	RNK	Halifax, Henry, Pittsylvania, City of Danville	60 min
Jun 22, 2:55 PM EDT	Severe Thunderstorm Warning	RNK	Appomattox, Buckingham	50 min
Jun 22, 3:07 PM EDT	Severe Thunderstorm Warning	AKQ	Cumberland, Fluvanna, Goochland	53 min
Jun 22, 3:30 PM EDT	Severe Thunderstorm Warning	LWX	King George, Spotsylvania, Stafford	45 min
Jun 22, 3:48 PM EDT	Severe Thunderstorm Warning	LWX	King George, Spotsylvania, Stafford, City of Fredericksburg	42 min
Jun 22, 4:00 PM EDT	Severe Thunderstorm Warning	AKQ	Chesterfield, Powhatan	45 min
Jun 22, 4:02 PM EDT	Severe Thunderstorm Warning	LWX	Charles	28 min
Jun 22, 4:08 PM EDT	Severe Thunderstorm Warning	LWX	Washington	52 min
Jun 22, 4:11 PM EDT	Severe Thunderstorm Warning	PHI	Cape May, Cumberland	44 min
Jun 22, 4:15 PM EDT	Severe Thunderstorm Warning	RNK	Halifax	30 min
Jun 22, 4:17 PM EDT	Severe Thunderstorm Warning	AKQ	Caroline, Essex, King and Queen, Richmond, Westmoreland	43 min
Jun 22, 4:23 PM EDT	Severe Thunderstorm Warning	AKQ	City of Chesapeake, City of Norfolk, City of Portsmouth, City of Virginia Beach	52 min
Jun 22, 4:36 PM EDT	Severe Thunderstorm Warning	LWX	Calvert	24 min
Jun 22, 4:39 PM EDT	Severe Thunderstorm Warning	LWX	Frederick, Washington	51 min
Jun 22, 4:40 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick, Shenandoah, Warren, City of Winchester	50 min
Jun 22, 4:48 PM EDT	Severe Thunderstorm Warning	LWX	Washington	42 min
Jun 22, 4:49 PM EDT	Severe Thunderstorm Warning	AKQ	Charles City, Hanover, Henrico, New Kent	30 min
Jun 22, 5:16 PM EDT	Severe Thunderstorm Warning	PHI	Atlantic, Burlington, Ocean	59 min
Jun 22, 5:20 PM EDT	Severe Thunderstorm Warning	LWX	Carroll, Frederick	40 min
Jun 22, 5:23 PM EDT	Severe Thunderstorm Warning	LWX	Calvert, Saint Mary's	52 min
Jun 22, 5:31 PM EDT	Severe Thunderstorm Warning	AKQ	Isle of Wight, City of Suffolk	44 min
Jun 22, 5:37 PM EDT	Severe Thunderstorm Warning	LWX	Clarke, Frederick, Loudoun, City of Winchester	53 min
Jun 22, 5:41 PM EDT	Severe Thunderstorm Warning	AKQ	Charles City, Prince George, Surry, Sussex	49 min
Jun 22, 5:47 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Frederick	43 min
Jun 22, 5:55 PM EDT	Severe Thunderstorm Warning	LWX	Harford	40 min
Jun 22, 6:10 PM EDT	Severe Thunderstorm Warning	LWX	Montgomery	50 min
Jun 22, 6:10 PM EDT	Severe Thunderstorm Warning	RNK	Amherst	65 min
Jun 22, 6:13 PM EDT	Severe Thunderstorm Warning	PHI	Cecil	62 min
Jun 22, 6:23 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Harford, City of Baltimore	37 min
Jun 22, 6:57 PM EDT	Severe Thunderstorm Warning	LWX	Montgomery	48 min
Jun 22, 7:03 PM EDT	Severe Thunderstorm Warning	LWX	Albemarle, City of Charlottesville	42 min
Jun 22, 7:04 PM EDT	Severe Thunderstorm Warning	PHI	Burlington, Camden, Gloucester	56 min
Jun 22, 7:06 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	54 min
Jun 22, 7:24 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Greene, Madison, Page, Rappahannock, Rockingham	51 min
Jun 22, 7:29 PM EDT	Severe Thunderstorm Warning	LWX	Howard, Montgomery, Prince George's	46 min
Jun 22, 7:42 PM EDT	Flash Flood Warning	PHI	New Castle	93 min
Jun 22, 7:43 PM EDT	Severe Thunderstorm Warning	LWX	Anne Arundel, Montgomery, Prince George's	47 min
Jun 22, 7:57 PM EDT	Severe Thunderstorm Warning	PHI	New Castle	69 min
Jun 22, 8:10 PM EDT	Severe Thunderstorm Warning	LWX	Culpeper, Greene, Madison, Orange	23 min
Jun 22, 8:15 PM EDT	Flash Flood Warning	PHI	Kent, New Castle	53 min
Jun 22, 8:19 PM EDT	Flash Flood Warning	PHI	Cumberland, Gloucester, Salem	70 min
Jun 22, 8:27 PM EDT	Severe Thunderstorm Warning	PHI	Kent, New Castle	45 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, 6.2 hours before the alert went out and 125 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 243 J/kg
Mixed-layer CIN: -153 J/kg
Mixed-layer LCL: 1563 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: -24 m²/s²
0-3 km storm-relative helicity: 115 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.2

Open this sounding in Storm Lab

The text

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

185 
WWUS20 KWNS 221816
SEL8
SPC WW 221816
DCZ000-DEZ000-MDZ000-NJZ000-VAZ000-CWZ000-230100-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 418
NWS STORM PREDICTION CENTER NORMAN OK
215 PM EDT FRI JUN 22 2012

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

       DISTRICT OF COLUMBIA
       DELAWARE
       MARYLAND EXCEPT PANHANDLE
       SOUTHERN NEW JERSEY
       CENTRAL AND EASTERN VIRGINIA
       COASTAL WATERS

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 215 PM UNTIL 900
PM EDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 95
STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES SOUTH
SOUTHWEST OF SOUTH HILL VIRGINIA TO 5 MILES NORTHWEST OF
WILMINGTON DELAWARE.  FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 417...

DISCUSSION...TSTMS FCST TO CONTINUE INCREASING IN COVERAGE/INTENSITY
THROUGH REMAINDER AFTERNOON AHEAD OF SFC COLD FRONT...AMIDST
1000-2500 J/KG MLCAPE AND 20-30 KT EFFECTIVE SHEAR MAGNITUDES.  THIS
WILL SUPPORT PRIMARILY MULTICELLULAR CONVECTIVE MODES AND THREAT FOR
DAMAGING DOWNDRAFTS.  ISOLATED LARGE HAIL ALSO IS POSSIBLE.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 27025.


...EDWARDS

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 22, 12:18 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	2 hr
Jun 22, 4:10 PM EDT	Mesoscale Discussion	SPC	Kent, Sussex	2 hr
Jun 22, 6:42 PM EDT	Mesoscale Discussion	SPC	Kent, New Castle, Sussex	63 min
Jun 22, 1:41 PM EDT	Severe Thunderstorm Watch	SPC	Bergen, Burlington, Camden, Essex, Hudson, Hunterdon and 10 more	7 hr
Jun 22, 4:33 PM EDT	Mesoscale Discussion	SPC	Bergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more	87 min

Nearby

Severe Thunderstorm Watches in Virginia, 2012 Severe Thunderstorm Watches in Maryland, 2012 Severe Thunderstorm Watches in New Jersey, 2012 Every severe thunderstorm watch in 2012

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.