Alert archive / Virginia / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 528

July 26, 20125 states

The Storm Prediction Center issued this severe thunderstorm watch at Jul 26, 2012, 5:54 PM EDT for 5 states. It was in force for 6 hr.

The area

The outline as issued.

The facts

Issued: Jul 26, 2012, 5:54 PM EDT (21:54 UTC)
Expired: Jul 26, 2012, 11:38 PM EDT
In force: 6 hr
Issued by: the Storm Prediction Center
Largest hail expected: 1.5 in
Strongest gust expected: 60 kt

All 68 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, Salem County, NJ, Arlington County, VA, Caroline County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Essex County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Richmond County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Westmoreland 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 Sterling radar (KLWX), 12 km from the middle of the area, began a volume at 21:54 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: 20%
One or more EF2 to EF5 tornadoes: 5%
Ten or more severe wind reports: 70%
One or more gusts of 65 knots or more: 40%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 20%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

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

Issued	Product	Office	Counties	Lasted
Jul 26, 7:13 PM EDT	Severe Thunderstorm Warning	LWX	Allegany	47 min
Jul 26, 7:57 PM EDT	Severe Thunderstorm Warning	LWX	Allegany, Washington	48 min
Jul 26, 8:31 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Frederick, Harford	44 min
Jul 26, 9:26 PM EDT	Severe Thunderstorm Warning	LWX	Baltimore, Carroll, Harford, Howard, City of Baltimore	49 min
Jul 26, 9:48 PM EDT	Severe Thunderstorm Warning	LWX	Fauquier, Loudoun, Prince William	15 min
Jul 26, 9:56 PM EDT	Flash Flood Warning	LWX	Baltimore, Carroll, Harford, City of Baltimore	3 hr

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, 9.9 hours before the alert went out and 20 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: 1172 J/kg
Mixed-layer CIN: -226 J/kg
Mixed-layer LCL: 985 m above ground
0-6 km bulk shear: 29 kt
0-1 km storm-relative helicity: 180 m²/s²
0-3 km storm-relative helicity: 170 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

172 
WWUS20 KWNS 262155
SEL8  
SPC WW 262155
DCZ000-DEZ000-MDZ000-NJZ000-VAZ000-WVZ000-CWZ000-270500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 528
NWS STORM PREDICTION CENTER NORMAN OK
555 PM EDT THU JUL 26 2012

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

       DISTRICT OF COLUMBIA
       DELAWARE
       MARYLAND
       SOUTHERN NEW JERSEY
       NORTHERN VIRGINIA
       WEST VIRGINIA PANHANDLE
       COASTAL WATERS

EFFECTIVE THIS THURSDAY AFTERNOON AND FRIDAY MORNING FROM 555 PM
UNTIL 100 AM EDT.

HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 55 MILES NORTHWEST
OF STAUNTON VIRGINIA TO 50 MILES EAST SOUTHEAST OF DOVER
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 524...WW 525...WW
526...WW 527...

DISCUSSION...TRAILING PORTION OF EXPANSIVE QLCS ONGOING FROM THE
LOWER HUDSON VALLEY INTO UPPER OH VALLEY IS EXPECTED TO PROGRESS
SEWD ACROSS WATCH AREA THIS EVENING.  AMBIENT INFLOW AIR MASS IS HOT
AND MOIST WITH MLCAPE OF 2000-3000+ J/KG.  WHEN COUPLED WITH A
UNIDIRECTIONAL...WLY WIND FIELD...SETUP WILL REMAIN SUPPORTIVE OF
FORWARD PROPAGATION OF QLCS WITH AN ATTENDANT RISK FOR DAMAGING
WINDS AND SOME HAIL.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 30035.


...MEAD

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 26, 3:08 PM EDT	Mesoscale Discussion	SPC	Kent, Sussex	2 hr
Jul 26, 3:37 PM EDT	Mesoscale Discussion	SPC	New Castle	113 min
Jul 26, 1:16 PM EDT	Severe Thunderstorm Watch	SPC	Garrett	9 hr
Jul 26, 6:06 PM EDT	Mesoscale Discussion	SPC	Garrett	84 min
Jul 26, 3:57 PM EDT	Severe Thunderstorm Watch	SPC	Bergen, Burlington, Camden, Essex, Gloucester, Hudson and 11 more	6 hr
Jul 26, 6:04 PM EDT	Mesoscale Discussion	SPC	Bergen, Burlington, Camden, Essex, Hudson, Hunterdon and 10 more	86 min
Jul 26, 7:28 PM EDT	Mesoscale Discussion	SPC	Bergen, Burlington, Camden, Essex, Hudson, Hunterdon and 10 more	92 min
Jul 26, 6:26 PM EDT	Severe Thunderstorm Watch	SPC	Buchanan, Dickenson	7 hr
Jul 26, 4:31 AM EDT	Mesoscale Discussion	SPC	Brooke, Doddridge, Hancock, Harrison, Marion, Marshall and 8 more	89 min
Jul 26, 12:26 PM EDT	Mesoscale Discussion	SPC	Brooke, Hancock, Ohio	2 hr
Jul 26, 4:57 PM EDT	Mesoscale Discussion	SPC	Boone, Logan, Mingo, Wayne	2 hr

Nearby

Severe Thunderstorm Watches in Virginia, 2012 Severe Thunderstorm Watches in Maryland, 2012 Severe Thunderstorm Watches in West Virginia, 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.