Alert archive / Virginia / Severe Thunderstorm Warnings in 2020

Severe Thunderstorm Warning 397, NWS Baltimore/Washington

August 25, 20204 counties in Virginia

NWS Baltimore/Washington issued this severe thunderstorm warning at Aug 25, 2020, 6:42 PM EDT for 4 counties in Virginia. It was in force for 48 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued
Aug 25, 2020, 6:42 PM EDT (22:42 UTC)
Expired
Aug 25, 2020, 7:30 PM EDT
In force
48 min
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Hail
0.75 in
Wind
60.0 mph

Counties Fauquier County, VA, Loudoun County, VA, Rappahannock County, VA, Warren County, VA

The radar

The Sterling radar (KLWX), 42 km from the middle of the area, began a volume at 22:43 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.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Aug 25, 3:34 PM EDTSevere Thunderstorm WatchSPC7 hr

The nearest sounding before it

Washington/Dulle, VA (KIAD), launched 12:00Z, 10.7 hours before the alert went out and 49 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 2020-08-25Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 573 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 2020-08-25The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 176 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
573 J/kg
Mixed-layer CIN
-96 J/kg
Mixed-layer LCL
1117 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
176 m²/s²
0-3 km storm-relative helicity
176 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.8

Open this sounding in Storm Lab

The office that day

Everything else NWS Baltimore/Washington issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 25, 10:18 AM EDTSevere Thunderstorm WarningLWXFrederick27 min
Aug 25, 11:27 AM EDTSevere Thunderstorm WarningLWXClarke, Fauquier, Loudoun33 min
Aug 25, 4:50 PM EDTSevere Thunderstorm WarningLWXFrederick40 min
Aug 25, 5:24 PM EDTSevere Thunderstorm WarningLWXClarke, Frederick51 min
Aug 25, 5:41 PM EDTSevere Thunderstorm WarningLWXFrederick, Shenandoah, City of Winchester49 min
Aug 25, 6:06 PM EDTSevere Thunderstorm WarningLWXClarke, Fauquier, Frederick, Loudoun, Warren, City of Winchester39 min
Aug 25, 6:27 PM EDTSevere Thunderstorm WarningLWXFairfax, Fauquier, Loudoun, Prince William, City of Manassas, City of Manassas Park48 min
Aug 25, 6:46 PM EDTSpecial Marine WarningLWX119 min
Aug 25, 6:57 PM EDTSevere Thunderstorm WarningLWXArlington, Fairfax, City of Alexandria, City of Fairfax, City of Falls Church48 min
Aug 25, 7:08 PM EDTSevere Thunderstorm WarningLWXCulpeper, Fauquier, Prince William, Stafford, City of Manassas, City of Manassas Park52 min
Aug 25, 7:36 PM EDTSevere Thunderstorm WarningLWXKing George, Prince William, Stafford, City of Fredericksburg39 min
Aug 25, 7:37 PM EDTSpecial Marine WarningLWX83 min
Aug 25, 4:12 PM EDTSevere Thunderstorm WarningLWXAllegany, Washington48 min
Aug 25, 4:52 PM EDTSevere Thunderstorm WarningLWXAllegany38 min
Aug 25, 5:44 PM EDTAreal Flood WarningLWXAllegany94 min
Aug 25, 7:11 PM EDTSevere Thunderstorm WarningLWXPrince George's49 min
Aug 25, 7:51 PM EDTSevere Thunderstorm WarningLWXAnne Arundel, Calvert, Prince George's39 min
Aug 25, 5:19 PM EDTSevere Thunderstorm WarningLWXHampshire41 min
Aug 25, 5:26 PM EDTSevere Thunderstorm WarningLWXGrant33 min
Aug 25, 5:27 PM EDTSevere Thunderstorm WarningLWXMineral18 min

Nearby

Severe Thunderstorm Warnings in Virginia, 2020Every severe thunderstorm warning in 2020

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.