Alert archive / Virginia / Flash Flood Warnings in 2020
Flash Flood Warning 38, NWS Baltimore/Washington
NWS Baltimore/Washington issued this flash flood warning at Aug 12, 2020, 4:07 AM EDT for 4 counties in Virginia. It was in force for 118 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 12, 2020, 4:07 AM EDT (08:07 UTC)
- Expired
- Aug 12, 2020, 6:05 AM EDT
- In force
- 118 min
- Issued by
- NWS Baltimore/Washington
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties City of Manassas, VA, City of Manassas Park, VA, Fairfax County, VA, Prince William County, VA
The radar
The Sterling radar (KLWX), 24 km from the middle of the area, began a volume at 08:08 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 nearest sounding before it
Washington/Dulle, VA (KIAD), launched 00:00Z, 8.1 hours before the alert went out and 20 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
- 1124 J/kg
- Mixed-layer CIN
- -15 J/kg
- Mixed-layer LCL
- 1414 m above ground
- 0-6 km bulk shear
- 14 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 88 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
What forecasters said that day
The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Baltimore/Washington wrote its last area forecast discussion before this flash flood warning went out at Aug 11, 9:25 PM EDT, 6 hours 42 minutes earlier.
Area forecast discussion, Aug 11, 9:25 PM EDT, 6 hours 42 minutes before
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</html>Hazardous weather outlook, Aug 11, 3:25 PM EDT, 12 hours 42 minutes before
Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 325 PM EDT Tue Aug 11 2020 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-121000- Chesapeake Bay north of Pooles Island MD- Chesapeake Bay from Pooles Island to Sandy Point MD- Chesapeake Bay from Sandy Point to North Beach MD- Chesapeake Bay from North Beach to Drum Point MD- Chesapeake Bay from Drum Point MD to Smith Point VA- Tidal Potomac from Key Bridge to Indian Head MD- Tidal Potomac from Indian Head to Cobb Island MD- Tidal Potomac from Cobb Island MD to Smith Point VA- Patapsco River including Baltimore Harbor- Chester River to Queenstown MD-Eastern Bay- Choptank River to Cambridge MD and the Little Choptank River- Patuxent River to Broomes Island MD- Tangier Sound and the inland waters surrounding Bloodsworth Island-District of Columbia-Southern Baltimore-Prince Georges- Anne Arundel-Charles-St. Marys-Calvert-Southeast Harford- Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 325 PM EDT Tue Aug 11 2020 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and adjacent counties in central Maryland and northern Virginia as well as the District of Columbia. .DAY ONE...This Afternoon and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday A Flash Flood Watch is in effect from Wednesday afternoon through Wednesday evening. Showers and thunderstorms are likely Thursday through Saturday, some of which will produce locally heavy rainfall. A few storms could cause isolated instances of flash flooding. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-121000- Washington-Frederick MD-Carroll-Northern Baltimore- Extreme Western Allegany-Central and Eastern Allegany- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke- Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Highland- Eastern Highland-Western Loudoun-Eastern Loudoun- Northern Virginia Blue Ridge-Central Virginia Blue Ridge- Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant- Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 325 PM EDT Tue Aug 11 2020 This Hazardous Weather Outlook is for eastern West Virginia, northern and central Virginia, and central and western Maryland with the exception of Garrett County. .DAY ONE...This Afternoon and Tonight No hazardous weather is expected at this time. .DAYS TWO THROUGH SEVEN...Wednesday through Monday A Flash Flood Watch is in effect from Wednesday afternoon through Wednesday evening. Showers and thunderstorms are likely Thursday through Saturday, some of which will produce locally heavy rainfall. A few storms could cause isolated instances of flash flooding. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time.
The office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 11, 9:16 PM EDT | Severe Thunderstorm Warning | LWX | Albemarle, Greene, Rockingham | 30 min |
| Aug 12, 2:01 AM EDT | Areal Flood Warning | LWX | Greene, Madison, Rockingham | 4 hr |
| Aug 12, 3:30 AM EDT | Areal Flood Warning | LWX | Nelson | 6 hr |
| Aug 12, 3:55 AM EDT | Areal Flood Warning | LWX | Fairfax, Prince William, City of Manassas, City of Manassas Park | 8 hr |
| Aug 12, 6:05 AM EDT | Areal Flood Warning | LWX | Fairfax, Prince William | 6 hr |
| Aug 12, 6:19 AM EDT | Areal Flood Warning | LWX | Fairfax | 8 hr |
| Aug 12, 7:21 AM EDT | Flash Flood Warning | LWX | Prince William | 109 min |
| Aug 12, 2:08 PM EDT | Special Marine Warning | LWX | 22 min | |
| Aug 12, 2:22 PM EDT | Special Marine Warning | LWX | 31 min | |
| Aug 12, 5:10 PM EDT | Special Marine Warning | LWX | 60 min | |
| Aug 12, 5:27 PM EDT | Special Marine Warning | LWX | 63 min | |
| Aug 12, 5:39 PM EDT | Special Marine Warning | LWX | 32 min | |
| Aug 12, 5:49 PM EDT | Severe Thunderstorm Warning | LWX | Highland | 41 min |
| Aug 12, 6:26 PM EDT | Flash Flood Warning | LWX | Albemarle, Nelson | 4 hr |
| Aug 12, 6:37 PM EDT | Special Marine Warning | LWX | 83 min | |
| Aug 12, 6:54 PM EDT | Flash Flood Warning | LWX | Fairfax, Loudoun | 2 hr |
| Aug 12, 7:08 PM EDT | Areal Flood Warning | LWX | Albemarle, Augusta, Rockingham, City of Waynesboro | 3 hr |
| Aug 12, 7:22 PM EDT | Special Marine Warning | LWX | 56 min | |
| Aug 12, 7:53 PM EDT | Areal Flood Warning | LWX | Loudoun | 2 hr |
| Aug 12, 1:30 PM EDT | Areal Flood Warning | LWX | Baltimore, Howard | 57 min |
| Aug 12, 4:23 PM EDT | Flash Flood Warning | LWX | Harford | 3 hr |
| Aug 12, 4:54 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel | 36 min |
| Aug 12, 5:05 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Baltimore, Howard | 40 min |
| Aug 12, 5:13 PM EDT | Flash Flood Warning | LWX | Anne Arundel | 4 hr |
| Aug 12, 5:23 PM EDT | Severe Thunderstorm Warning | LWX | Baltimore, Howard, City of Baltimore | 38 min |
| Aug 12, 5:35 PM EDT | Areal Flood Warning | LWX | Baltimore, Howard, City of Baltimore | 7 hr |
| Aug 12, 5:42 PM EDT | Flash Flood Warning | LWX | Baltimore, Howard, City of Baltimore | 3 hr |
| Aug 12, 5:49 PM EDT | Flash Flood Warning | LWX | Howard, Montgomery, Prince George's | 3 hr |
| Aug 12, 6:10 PM EDT | Flash Flood Warning | LWX | Anne Arundel, Baltimore, City of Baltimore | 3 hr |
| Aug 12, 6:50 PM EDT | Areal Flood Warning | LWX | Frederick | 108 min |
Nearby
Flash Flood Warnings in Virginia, 2020Every flash flood 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.