Alert archive / Virginia / Severe Thunderstorm Watches in 2006

Severe Thunderstorm Watch 613

July 18, 200612 counties in Maryland; 34 counties in Virginia; 8 counties in West Virginia

The Storm Prediction Center issued this severe thunderstorm watch at Jul 18, 2006, 4:27 PM EDT for 12 counties in Maryland; 34 counties in Virginia; 8 counties in West Virginia. It was in force for 5 hr.

The area

The outline as issued.

The facts

Issued
Jul 18, 2006, 4:27 PM EDT (20:27 UTC)
Expired
Jul 18, 2006, 9:23 PM EDT
In force
5 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 54 counties

Allegany County, MD, Anne Arundel County, MD, Baltimore County, MD, Carroll County, MD, Charles County, MD, City of Baltimore, MD, Frederick County, MD, Harford County, MD, Howard County, MD, Montgomery County, MD, Prince George's County, MD, Washington County, MD, Albemarle County, VA, Arlington County, VA, Augusta County, VA, City of Alexandria, VA, City of Charlottesville, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Harrisonburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Staunton, VA, City of Waynesboro, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, Greene County, VA, Highland County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Nelson County, VA, Orange County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Rockingham County, VA, Shenandoah County, VA, Spotsylvania County, VA, Stafford County, VA, Warren 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), 67 km from the middle of the area, began a volume at 20:26 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
30%
One or more gusts of 65 knots or more
20%
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
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Jul 18, 4:48 PM EDTSevere Thunderstorm WarningLWXRockingham57 min
Jul 18, 4:49 PM EDTSevere Thunderstorm WarningLWXPrince George's27 min
Jul 18, 4:57 PM EDTSevere Thunderstorm WarningLWXMorgan48 min
Jul 18, 5:09 PM EDTSevere Thunderstorm WarningLWXHampshire66 min
Jul 18, 5:14 PM EDTSevere Thunderstorm WarningLWXShenandoah, Warren56 min
Jul 18, 5:40 PM EDTSevere Thunderstorm WarningLWXMadison, Page, Rappahannock65 min
Jul 18, 5:43 PM EDTSevere Thunderstorm WarningLWXRockingham, City of Harrisonburg25 min
Jul 18, 5:45 PM EDTSevere Thunderstorm WarningLWXFrederick, City of Winchester60 min
Jul 18, 5:57 PM EDTSevere Thunderstorm WarningLWXCarroll, Frederick, Washington63 min
Jul 18, 6:23 PM EDTFlash Flood WarningLWXMorgan3 hr
Jul 18, 6:26 PM EDTSevere Thunderstorm WarningLWXAllegany49 min
Jul 18, 6:37 PM EDTSevere Thunderstorm WarningLWXBaltimore, Harford38 min
Jul 18, 6:53 PM EDTSevere Thunderstorm WarningLWXBerkeley, Morgan67 min
Jul 18, 7:06 PM EDTSevere Thunderstorm WarningLWXFrederick54 min
Jul 18, 7:15 PM EDTSevere Thunderstorm WarningLWXBaltimore45 min
Jul 18, 7:26 PM EDTSevere Thunderstorm WarningLWXCarroll, Howard40 min
Jul 18, 7:28 PM EDTSevere Thunderstorm WarningLWXHarford47 min
Jul 18, 8:14 PM EDTSevere Thunderstorm WarningLWXHarford46 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, 8.5 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 2006-07-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1430 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 2006-07-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -56 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
1430 J/kg
Mixed-layer CIN
-125 J/kg
Mixed-layer LCL
1578 m above ground
0-6 km bulk shear
16 kt
0-1 km storm-relative helicity
-56 m²/s²
0-3 km storm-relative helicity
-7 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 18, 3:15 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Calvert, Carroll, Charles, Frederick and 7 more60 min
Jul 18, 6:37 PM EDTSevere Thunderstorm WatchSPCCaroline, Cecil, Kent, Queen Anne's, Talbot6 hr

Nearby

Severe Thunderstorm Watches in Virginia, 2006Severe Thunderstorm Watches in Maryland, 2006Severe Thunderstorm Watches in West Virginia, 2006Every severe thunderstorm watch in 2006

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.