Alert archive / Virginia / Severe Thunderstorm Watches in 2007
Severe Thunderstorm Watch 437
The Storm Prediction Center issued this severe thunderstorm watch at Jun 21, 2007, 5:10 PM EDT for 14 counties in Maryland; 20 counties in Virginia; 7 counties in West Virginia. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jun 21, 2007, 5:10 PM EDT (21:10 UTC)
- Expired
- Jun 21, 2007, 8:45 PM EDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 41 counties
Allegany County, MD, 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 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, Loudoun County, VA, Madison County, VA, Page County, VA, Prince William County, VA, Rappahannock County, VA, Shenandoah 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
The radar
The Sterling radar (KLWX), 57 km from the middle of the area, began a volume at 21:12 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
- 5%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 30%
- 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
- 70%
Warnings issued inside it
5 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 5:17 PM EDT | Severe Thunderstorm Warning | LWX | Howard, Montgomery | 35 min |
| Jun 21, 5:23 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, City of Baltimore | 33 min |
| Jun 21, 5:31 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel | 59 min |
| Jun 21, 5:43 PM EDT | Severe Thunderstorm Warning | LWX | Prince George's | 62 min |
| Jun 21, 7:30 PM EDT | Severe Thunderstorm Warning | LWX | Grant | 29 min |
The nearest sounding before it
Phillips Aaf/Abe, MD (KAPG), launched 12:00Z, 9.2 hours before the alert went out and 145 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1729 m above ground
- 0-6 km bulk shear
- 33 kt
- 0-1 km storm-relative helicity
- -57 m²/s²
- 0-3 km storm-relative helicity
- 13 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 21, 1:25 PM EDT | Mesoscale Discussion | SPC | Bradford, Lackawanna, Luzerne, Lycoming, Monroe, Pike and 5 more | 95 min |
| Jun 21, 2:12 PM EDT | Mesoscale Discussion | SPC | Allegheny, Armstrong, Beaver, Butler, Fayette, Indiana and 5 more | 93 min |
| Jun 21, 2:47 PM EDT | Severe Thunderstorm Watch | SPC | Bradford, Carbon, Lackawanna, Luzerne, Monroe, Pike and 3 more | 7 hr |
| Jun 21, 5:58 PM EDT | Mesoscale Discussion | SPC | Lackawanna, Monroe, Northampton, Pike, Susquehanna, Wayne | 62 min |
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.