Alert archive / Virginia / Severe Thunderstorm Watches in 2007

Severe Thunderstorm Watch 301

May 27, 200713 counties in Maryland; 22 counties in Virginia; Berkeley County, Jefferson County, Morgan County, West Virginia

The Storm Prediction Center issued this severe thunderstorm watch at May 27, 2007, 4:43 PM EDT for 13 counties in Maryland; 22 counties in Virginia; Berkeley County, Jefferson County, Morgan County, West Virginia. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued
May 27, 2007, 4:43 PM EDT (20:43 UTC)
Expired
May 27, 2007, 8:48 PM EDT
In force
4 hr
Issued by
the Storm Prediction Center
Largest hail expected
1.5 in
Strongest gust expected
60 kt
All 38 counties

Anne Arundel County, MD, Baltimore County, MD, Calvert 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, Saint Mary's County, MD, Washington County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, City of Fredericksburg, VA, City of Manassas, VA, City of Manassas Park, VA, City of Winchester, VA, Clarke County, VA, Culpeper County, VA, Fairfax County, VA, Fauquier County, VA, Frederick County, VA, King George County, VA, Loudoun County, VA, Madison County, VA, Orange County, VA, Prince William County, VA, Rappahannock County, VA, Spotsylvania County, VA, Stafford County, VA, Warren County, VA, Berkeley County, WV, Jefferson County, WV, Morgan County, WV

The radar

The Sterling radar (KLWX), 12 km from the middle of the area, began a volume at 20:43 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
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
60%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
May 27, 4:55 PM EDTSevere Thunderstorm WarningLWXFauquier51 min
May 27, 5:10 PM EDTSevere Thunderstorm WarningLWXClarke31 min
May 27, 5:17 PM EDTSevere Thunderstorm WarningLWXLoudoun73 min
May 27, 5:19 PM EDTSevere Thunderstorm WarningLWXPrince William, City of Manassas, City of Manassas Park45 min
May 27, 5:51 PM EDTSevere Thunderstorm WarningLWXFairfax, City of Fairfax, City of Falls Church54 min
May 27, 6:08 PM EDTSevere Thunderstorm WarningLWXMontgomery53 min
May 27, 6:19 PM EDTSevere Thunderstorm WarningLWXArlington, City of Alexandria44 min
May 27, 6:38 PM EDTSevere Thunderstorm WarningLWXCarroll67 min
May 27, 6:43 PM EDTSevere Thunderstorm WarningLWXPrince George's47 min
May 27, 6:55 PM EDTSevere Thunderstorm WarningLWXHarford50 min
May 27, 7:09 PM EDTSevere Thunderstorm WarningLWXAnne Arundel51 min
May 27, 7:11 PM EDTSevere Thunderstorm WarningLWXBaltimore49 min
May 27, 7:48 PM EDTSevere Thunderstorm WarningLWXHarford42 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, 8.7 hours before the alert went out and 15 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 2007-05-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 224 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 2007-05-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 9 square meters per square second.193958Sfc1 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
224 J/kg
Mixed-layer CIN
-196 J/kg
Mixed-layer LCL
1384 m above ground
0-6 km bulk shear
21 kt
0-1 km storm-relative helicity
9 m²/s²
0-3 km storm-relative helicity
14 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
May 27, 4:30 PM EDTMesoscale DiscussionSPCBaltimore, Carroll, Charles, Frederick, Howard, Montgomery and 3 more60 min
May 27, 6:56 PM EDTMesoscale DiscussionSPCAnne Arundel, Baltimore, Calvert, Carroll, Cecil, Charles and 10 more2 hr
May 27, 12:45 PM EDTMesoscale DiscussionSPCBrooke, Hancock, Marshall, Ohio, Pleasants, Tyler and 1 more90 min
May 27, 1:52 PM EDTSevere Thunderstorm WatchSPCBrooke, Hancock, Marshall, Ohio6 hr

Nearby

Severe Thunderstorm Watches in Virginia, 2007Severe Thunderstorm Watches in Maryland, 2007Severe Thunderstorm Watches in West Virginia, 2007Every severe thunderstorm watch in 2007

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.