Alert archive / Virginia / Flash Flood Warnings in 2021
Flash Flood Warning 20, NWS Baltimore/Washington
NWS Baltimore/Washington issued this flash flood warning at Jul 1, 2021, 8:30 PM EDT for Montgomery County, Prince George's County, Maryland; 5 counties in Virginia. It was in force for 2 hr. 2 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
- Jul 1, 2021, 8:30 PM EDT (00:30 UTC)
- Expired
- Jul 1, 2021, 10:45 PM EDT
- In force
- 2 hr
- Issued by
- NWS Baltimore/Washington
- Area
- Storm-based polygon
- Damage threat
- Considerable
- Flood severity
- None
Counties Montgomery County, MD, Prince George's County, MD, Arlington County, VA, City of Alexandria, VA, City of Fairfax, VA, City of Falls Church, VA, Fairfax County, VA
The radar
The Sterling radar (KLWX), 27 km from the middle of the area, began a volume at 00:32 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 |
|---|---|---|---|
| Jul 1, 9:55 PM EDT | FLOOD | Stratmeade Springs, VA | STREAM GAUGE ON ACCOTINK CREEK REACHED MINOR FLOOD STAGE. |
| Jul 1, 9:55 PM EDT | FLOOD | Stratmeade Springs, VA | STREAM GAUGE ON DIFFICULT RUN REACHED MINOR FLOOD STAGE. |
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, 0.5 hours before the alert went out and 19 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
- 249 J/kg
- Mixed-layer CIN
- -11 J/kg
- Mixed-layer LCL
- 1099 m above ground
- 0-6 km bulk shear
- 37 kt
- 0-1 km storm-relative helicity
- -16 m²/s²
- 0-3 km storm-relative helicity
- 79 m²/s²
- Significant tornado parameter
- -0.0
- Supercell composite
- -0.7
The text
As transmitted.
802
WGUS51 KLWX 020030
FFWLWX
DCC001-MDC031-033-VAC013-059-510-600-610-020330-
/O.NEW.KLWX.FF.W.0020.210702T0030Z-210702T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Baltimore MD/Washington DC
830 PM EDT Thu Jul 1 2021
The National Weather Service in Sterling Virginia has issued a
* Flash Flood Warning for...
District of Columbia...
Southeastern Montgomery County in central Maryland...
Northwestern Prince Georges County in central Maryland...
Arlington County in northern Virginia...
Fairfax County in northern Virginia...
The City of Alexandria in northern Virginia...
The City of Fairfax in northern Virginia...
The City of Falls Church in northern Virginia...
* Until 1130 PM EDT.
* At 830 PM EDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Additional rainfall amounts of
2 to 3 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... Alexandria...
Centreville... Bethesda...
Reston... Annandale...
Clinton... Springfield...
College Park... Fort Washington...
Greenbelt... Fairfax...
Langley Park... Fort Hunt...
Vienna... Groveton...
Forestville... Falls Church...
Huntington... Largo...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3887 7748 3894 7740 3902 7713 3903 7702
3901 7696 3894 7687 3884 7682 3877 7687
3869 7716 3868 7726 3871 7730 3870 7733
3871 7732 3873 7736 3872 7737 3875 7739
3876 7742 3880 7745 3880 7747 3882 7751
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
BJL2 follow-up statements
065
WGUS71 KLWX 020154
FFSLWX
Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
954 PM EDT Thu Jul 1 2021
DCC001-MDC031-033-VAC013-059-510-600-610-020330-
/O.CON.KLWX.FF.W.0020.000000T0000Z-210702T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Montgomery MD-Prince Georges MD-Arlington VA-
Fairfax VA-City of Alexandria VA-City of Fairfax VA-City of Falls
Church VA-
954 PM EDT Thu Jul 1 2021
...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1130 PM EDT THIS
EVENING FOR SOUTHEASTERN MONTGOMERY, NORTHWESTERN PRINCE GEORGES,
ARLINGTON AND FAIRFAX COUNTIES AND THE DISTRICT OF COLUMBIA, THE
CITY OF ALEXANDRIA, THE CITY OF FAIRFAX AND THE CITY OF FALLS
CHURCH...
At 954 PM EDT, Doppler radar indicated that 1 to 2 inches of rain
has fallen within an hour across much of the warned area. Additional
rainfall amounts up to a half inch are possible. Excess runoff from
the rain will continue to cause creeks and streams to rise.
HAZARD...Life threatening flash flooding. Thunderstorms producing
flash flooding.
SOURCE...Radar.
IMPACT...Life threatening flash flooding of creeks and streams,
urban areas, highways, streets and underpasses.
Some locations that will experience flash flooding include...
Arlington... Alexandria...
Centreville... Bethesda...
Reston... Annandale...
Clinton... Springfield...
College Park... Fort Washington...
Greenbelt... Fairfax...
Langley Park... Fort Hunt...
Vienna... Groveton...
Forestville... Falls Church...
Huntington... Largo...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.
&&
LAT...LON 3887 7748 3894 7740 3902 7713 3903 7702
3901 7696 3894 7687 3884 7682 3877 7687
3869 7716 3868 7726 3871 7730 3870 7733
3871 7732 3873 7736 3872 7737 3875 7739
3876 7742 3880 7745 3880 7747 3882 7751
FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE
$$
BJL528
WGUS71 KLWX 020245
FFSLWX
Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
1045 PM EDT Thu Jul 1 2021
DCC001-MDC031-033-VAC013-059-510-600-610-020255-
/O.CAN.KLWX.FF.W.0020.000000T0000Z-210702T0330Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Montgomery MD-Prince Georges MD-Arlington VA-
Fairfax VA-City of Alexandria VA-City of Fairfax VA-City of Falls
Church VA-
1045 PM EDT Thu Jul 1 2021
...FLASH FLOOD WARNING FOR SOUTHEASTERN MONTGOMERY, NORTHWESTERN
PRINCE GEORGES, ARLINGTON AND FAIRFAX COUNTIES AND THE DISTRICT OF
COLUMBIA, THE CITY OF ALEXANDRIA, THE CITY OF FAIRFAX AND THE CITY
OF FALLS CHURCH HAS BEEN REPLACED WITH A FLOOD WARNING...
LAT...LON 3887 7748 3894 7740 3902 7713 3903 7702
3901 7696 3894 7687 3884 7682 3877 7687
3869 7716 3868 7726 3871 7730 3870 7733
3871 7732 3873 7736 3872 7737 3875 7739
3876 7742 3880 7745 3880 7747 3882 7751
$$
JMGThe office that day
Everything else NWS Baltimore/Washington issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 1, 8:47 PM EDT | Severe Thunderstorm Warning | LWX | Montgomery, Prince George's | 43 min |
| Jul 1, 8:58 PM EDT | Tornado Warning | LWX | Prince George's | 32 min |
| Jul 1, 9:11 PM EDT | Severe Thunderstorm Warning | LWX | Anne Arundel, Calvert, Prince George's | 49 min |
| Jul 1, 9:13 PM EDT | Tornado Warning | LWX | Prince George's | 21 min |
| Jul 1, 10:45 PM EDT | Areal Flood Warning | LWX | Montgomery, Prince George's | 3 hr |
| Jul 1, 8:17 PM EDT | Special Marine Warning | LWX | 79 min | |
| Jul 1, 8:26 PM EDT | Severe Thunderstorm Warning | LWX | Fairfax, Loudoun, Prince William, City of Fairfax, City of Manassas, City of Manassas Park | 37 min |
| Jul 1, 8:56 PM EDT | Special Marine Warning | LWX | 111 min | |
| Jul 1, 9:46 PM EDT | Special Marine Warning | LWX | 71 min | |
| Jul 1, 11:36 PM EDT | Special Marine Warning | LWX | 84 min | |
| Jul 2, 12:04 PM EDT | Small Craft Advisory | LWX | 31 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.