Alert archive / Virginia / Flash Flood Warnings in 2021
Flash Flood Warning 45, NWS Baltimore/Washington
NWS Baltimore/Washington issued this flash flood warning at Aug 16, 2021, 11:32 PM EDT for Arlington County, Fairfax County, Virginia; Montgomery County, Maryland. It was in force for 3 hr. 3 reports came from inside the area while it was in force.
The area
The outline as issued, with what was reported inside it.
The facts
- Issued
- Aug 16, 2021, 11:32 PM EDT (03:32 UTC)
- Expired
- Aug 17, 2021, 2:17 AM EDT
- In force
- 3 hr
- Issued by
- NWS Baltimore/Washington
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties Montgomery County, MD, Arlington County, VA, Fairfax County, VA
The radar
The Sterling radar (KLWX), 38 km from the middle of the area, began a volume at 03:35 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 was reported inside it
| Time | Report | Where | Remark |
|---|---|---|---|
| Aug 17, 12:17 AM EDT | FLASH FLOOD | 1 W Rivercrest, VA | VA-689 CHESTERBROOK ROAD WAS CLOSED AT LITTLE PIMMIT RUN. |
| Aug 17, 12:21 AM EDT | FLASH FLOOD | 1 N National Zoo, DC | BROAD BRANCH ROAD NW CLOSED BOTH WAYS BETWEEN BRANDYWINE STREET NW & BEACH DRIVE NW DUE TO FLASH FLOODING. |
| Aug 17, 1:45 AM EDT | FLASH FLOOD | Colesville, MD | RAPID RISE OF NORTHERN BRANCH OF THE ANACOSTIA RIVER TO ABOVE MINOR BETWEEN 145-230 AM. MAXIMUM LEVEL REACHED 9.31' (MINOR: 9.00'). |
Local storm reports filed while the alert was in force, from inside its polygon or its counties.
The nearest sounding before it
Washington/Dulle, VA (KIAD), launched 00:00Z, 3.5 hours before the alert went out and 31 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
- 376 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 504 m above ground
- 0-6 km bulk shear
- 11 kt
- 0-1 km storm-relative helicity
- 24 m²/s²
- 0-3 km storm-relative helicity
- 34 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
632
WGUS51 KLWX 170332
FFWLWX
DCC001-MDC031-VAC013-059-170630-
/O.NEW.KLWX.FF.W.0045.210817T0332Z-210817T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Baltimore MD/Washington DC
1132 PM EDT Mon Aug 16 2021
The National Weather Service in Sterling Virginia has issued a
* Flash Flood Warning for...
Northwestern District of Columbia...
Southeastern Montgomery County in central Maryland...
Northwestern Arlington County in northern Virginia...
East Central Fairfax County in northern Virginia...
* Until 230 AM EDT.
* At 1132 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 0.5 and 1.5 inches of
rain have fallen. Additional rainfall amounts of 1 to 2 inches are
possible in the warned area. Flash flooding is ongoing or expected
to begin shortly.
HAZARD...Life threatening flash flooding. Thunderstorms
producing flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
* Some locations that will experience flash flooding include...
Arlington... Bethesda...
Langley Park... Fairland...
White Oak... Takoma Park...
Colesville... Kemp Mill...
Chevy Chase... North Kensington...
South Kensington... Forest Glen...
Hillandale... Martin's Additions...
North Chevy Chase... Friendship Village...
Wheaton-Glenmont... American University...
Georgetown... Ballston...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3892 7717 3900 7710 3906 7707 3909 7703
3912 7696 3911 7692 3909 7692 3900 7699
3899 7699 3886 7711 3890 7716
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
BJL2 follow-up statements
564
WGUS71 KLWX 170513
FFSLWX
Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
113 AM EDT Tue Aug 17 2021
DCC001-MDC031-VAC013-059-170630-
/O.CON.KLWX.FF.W.0045.000000T0000Z-210817T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Montgomery MD-Arlington VA-Fairfax VA-
113 AM EDT Tue Aug 17 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 230 AM EDT EARLY THIS
MORNING FOR SOUTHEASTERN MONTGOMERY, NORTHWESTERN ARLINGTON AND EAST
CENTRAL FAIRFAX COUNTIES AND THE NORTHWESTERN DISTRICT OF COLUMBIA...
At 113 AM EDT, Doppler radar indicated thunderstorms producing heavy
rain across the warned area. Between 1 and 1.5 inches of rain have
fallen. Additional rainfall amounts up to 0.5 inches are possible in
the warned area. Flash flooding is ongoing or expected to begin
shortly.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
Some locations that will experience flash flooding include...
Arlington... Bethesda...
Langley Park... Fairland...
White Oak... Takoma Park...
Colesville... Kemp Mill...
Chevy Chase... North Kensington...
South Kensington... Forest Glen...
Hillandale... Martin's Additions...
North Chevy Chase... Friendship Village...
Wheaton-Glenmont... American University...
Georgetown... Ballston...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
Be especially cautious at night when it is harder to recognize the
dangers of flooding.
&&
LAT...LON 3892 7717 3900 7710 3906 7707 3909 7703
3912 7696 3911 7692 3909 7692 3900 7699
3899 7699 3886 7711 3890 7716
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
BRO599
WGUS71 KLWX 170617
FFSLWX
Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
217 AM EDT Tue Aug 17 2021
DCC001-MDC031-VAC013-059-170627-
/O.CAN.KLWX.FF.W.0045.000000T0000Z-210817T0630Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Montgomery MD-Arlington VA-Fairfax VA-
217 AM EDT Tue Aug 17 2021
...FLASH FLOOD WARNING FOR SOUTHEASTERN MONTGOMERY, NORTHWESTERN
ARLINGTON AND EAST CENTRAL FAIRFAX COUNTIES AND THE NORTHWESTERN
DISTRICT OF COLUMBIA HAS BEEN REPLACED WITH A FLOOD WARNING...
LAT...LON 3892 7717 3900 7710 3906 7707 3909 7703
3912 7696 3911 7692 3909 7692 3900 7699
3899 7699 3886 7711 3890 7716
$$The office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 16, 8:17 PM EDT | Areal Flood Warning | LWX | Albemarle, Nelson | 7 hr |
| Aug 16, 8:57 PM EDT | Areal Flood Warning | LWX | Albemarle, Greene, Madison, Rappahannock | 6 hr |
| Aug 16, 9:10 PM EDT | Flash Flood Warning | LWX | Nelson | 3 hr |
| Aug 16, 9:21 PM EDT | Flash Flood Warning | LWX | Albemarle, Greene, Madison, Rappahannock | 3 hr |
| Aug 16, 11:47 PM EDT | Special Marine Warning | LWX | 88 min | |
| Aug 17, 12:09 AM EDT | Areal Flood Warning | LWX | Loudoun | 4 hr |
| Aug 17, 1:10 AM EDT | Special Marine Warning | LWX | 50 min | |
| Aug 17, 1:59 AM EDT | Special Marine Warning | LWX | 86 min | |
| Aug 17, 2:17 AM EDT | Areal Flood Warning | LWX | Arlington, Fairfax | 4 hr |
| Aug 17, 2:20 AM EDT | Special Marine Warning | LWX | 65 min | |
| Aug 17, 8:07 AM EDT | Special Marine Warning | LWX | 83 min | |
| Aug 17, 8:34 AM EDT | Small Craft Advisory | LWX | 5 hr | |
| Aug 17, 8:50 AM EDT | Special Marine Warning | LWX | 115 min | |
| Aug 17, 9:31 AM EDT | Special Marine Warning | LWX | 85 min | |
| Aug 17, 1:18 PM EDT | Small Craft Advisory | LWX | 33 hr | |
| Aug 17, 1:54 PM EDT | Flash Flood Watch | LWX | Albemarle, Amherst, Arlington, Augusta, Clarke, Culpeper and 26 more | 27 hr |
| Aug 17, 6:10 PM EDT | Special Marine Warning | LWX | 70 min | |
| Aug 17, 2:37 AM EDT | Coastal Flood Advisory | LWX | 2 hr | |
| Aug 17, 6:40 PM EDT | Coastal Flood Advisory | LWX | 11 hr | |
| Aug 16, 8:47 PM EDT | Flash Flood Warning | LWX | Washington | 2 hr |
| Aug 16, 9:04 PM EDT | Flash Flood Warning | LWX | Allegany | 2 hr |
| Aug 17, 12:39 AM EDT | Coastal Flood Advisory | LWX | Anne Arundel | 100 min |
| Aug 17, 8:54 AM EDT | Flash Flood Watch | LWX | Anne Arundel, Baltimore, Cecil, Harford, City of Baltimore | 9 hr |
Nearby
Flash Flood Warnings in Virginia, 2021Flash Flood Warnings in Maryland, 2021Flash Flood Warnings in District of Columbia, 2021Every flash flood warning in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.