Alert archive / Virginia / Severe Thunderstorm Watches in 2014

Severe Thunderstorm Watch 416

July 13, 20145 states

The Storm Prediction Center issued this severe thunderstorm watch at Jul 13, 2014, 7:49 PM EDT for 5 states. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
Jul 13, 2014, 7:49 PM EDT (23:49 UTC)
Expired
Jul 14, 2014, 12:00 AM EDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1 in
Strongest gust expected
60 kt
All 51 counties

Kent County, DE, New Castle County, DE, Anne Arundel County, MD, Baltimore County, MD, Caroline County, MD, Carroll County, MD, Cecil County, MD, City of Baltimore, MD, Harford County, MD, Howard County, MD, Kent County, MD, Montgomery County, MD, Prince George's County, MD, Queen Anne's County, MD, Talbot County, MD, Burlington County, NJ, Camden County, NJ, Cumberland County, NJ, Gloucester County, NJ, Hunterdon County, NJ, Mercer County, NJ, Middlesex County, NJ, Morris County, NJ, Salem County, NJ, Somerset County, NJ, Sussex County, NJ, Warren County, NJ, Berks County, PA, Bucks County, PA, Carbon County, PA, Chester County, PA, Delaware County, PA, Lehigh County, PA, Monroe County, PA, Montgomery County, PA, Northampton County, PA, Philadelphia County, PA, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Loudoun County, VA, Prince William County, VA, Warren County, VA

The radar

The Philadelphia radar (KDIX), 132 km from the middle of the area, began a volume at 23:49 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
10%
One or more EF2 to EF5 tornadoes
2%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
5%
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
70%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 13, 8:07 PM EDTSevere Thunderstorm WarningLWXCarroll, Frederick, Washington38 min
Jul 13, 8:24 PM EDTSevere Thunderstorm WarningLWXCarroll, Frederick, Howard, Montgomery36 min
Jul 13, 8:33 PM EDTSevere Thunderstorm WarningPHICarbon, Lehigh, Monroe, Northampton57 min
Jul 13, 9:04 PM EDTSevere Thunderstorm WarningPHIBerks, Lehigh56 min
Jul 13, 9:17 PM EDTSevere Thunderstorm WarningLWXAnne Arundel, Baltimore, Howard, Montgomery, Prince George's28 min
Jul 13, 9:33 PM EDTSevere Thunderstorm WarningPHIWarren57 min
Jul 13, 9:44 PM EDTSevere Thunderstorm WarningPHIBerks, Bucks, Lehigh, Northampton46 min
Jul 13, 10:05 PM EDTSevere Thunderstorm WarningLWXBaltimore, Harford40 min
Jul 13, 10:14 PM EDTSevere Thunderstorm WarningPHINew Castle46 min
Jul 13, 10:27 PM EDTSevere Thunderstorm WarningPHIHunterdon, Morris, Somerset, Sussex, Warren47 min
Jul 13, 10:48 PM EDTSevere Thunderstorm WarningPHIKent, New Castle37 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, 11.8 hours before the alert went out and 221 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 2014-07-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 74 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 2014-07-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 158 square meters per square second.1939Sfc1 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
74 J/kg
Mixed-layer CIN
-162 J/kg
Mixed-layer LCL
1097 m above ground
0-6 km bulk shear
20 kt
0-1 km storm-relative helicity
158 m²/s²
0-3 km storm-relative helicity
82 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jul 13, 1:17 PM EDTSevere Thunderstorm WatchSPCGarrett7 hr
Jul 13, 4:06 PM EDTSevere Thunderstorm WatchSPCAllegany, Frederick, Washington6 hr
Jul 13, 5:49 PM EDTMesoscale DiscussionSPCBergen, Essex, Hunterdon, Morris, Passaic, Sussex and 1 more86 min
Jul 13, 7:06 PM EDTMesoscale DiscussionSPCHunterdon, Mercer, Morris, Somerset, Sussex, Warren84 min
Jul 13, 3:10 PM EDTMesoscale DiscussionSPCBroome, Chemung, Steuben, Tioga2 hr
Jul 13, 6:25 PM EDTSevere Thunderstorm WatchSPCColumbia, Dutchess, Orange, Putnam, Ulster4 hr
Jul 13, 12:37 PM EDTMesoscale DiscussionSPCAllegheny, Armstrong, Beaver, Butler, Clarion, Crawford and 10 more53 min
Jul 13, 6:18 PM EDTMesoscale DiscussionSPCAllegheny, Fayette, Greene, Washington, Westmoreland87 min

Nearby

Severe Thunderstorm Watches in Virginia, 2014Severe Thunderstorm Watches in Maryland, 2014Severe Thunderstorm Watches in New Jersey, 2014Every severe thunderstorm watch in 2014

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.