Alert archive / Virginia / Flash Flood Warnings in 2021

Flash Flood Warning 18, NWS Baltimore/Washington

July 1, 20214 counties in Virginia

NWS Baltimore/Washington issued this flash flood warning at Jul 1, 2021, 3:14 PM EDT for 4 counties in Virginia. It was in force for 3 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, 3:14 PM EDT (19:14 UTC)
Expired
Jul 1, 2021, 6:15 PM EDT
In force
3 hr
Issued by
NWS Baltimore/Washington
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

Counties Arlington County, VA, City of Alexandria, VA, City of Falls Church, VA, Fairfax County, VA

The radar

The Sterling radar (KLWX), 35 km from the middle of the area, began a volume at 19:14 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

TimeReportWhereRemark
Jul 1, 3:40 PM EDTFLASH FLOODKenilworth, DCALL LANES OF NANNIE HELEN BURROUGHS AVENUE NORTHEAST WERE BLOCKED BY HIGH WATER AT DC-295 ANACOSTIA FREEWAY.
Jul 1, 4:05 PM EDTFLASH FLOOD1 Sw Kenilworth, DCALL LANES OF EAST CAPITOL STREET BLOCKED BY FLOODING AT DC-295 ANACOSTIA FREEWAY.

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 12:00Z, 7.2 hours before the alert went out and 27 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 2021-07-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 604 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 2021-07-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 61 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
604 J/kg
Mixed-layer CIN
-48 J/kg
Mixed-layer LCL
928 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
61 m²/s²
0-3 km storm-relative helicity
108 m²/s²
Significant tornado parameter
0.2
Supercell composite
1.2

Open this sounding in Storm Lab

The text

As transmitted.

793 
WGUS51 KLWX 011914
FFWLWX
DCC001-VAC013-059-510-610-012215-
/O.NEW.KLWX.FF.W.0018.210701T1914Z-210701T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Baltimore MD/Washington DC
314 PM EDT Thu Jul 1 2021

The National Weather Service in Sterling Virginia has issued a

* Flash Flood Warning for...
  District of Columbia...
  Arlington County in northern Virginia...
  East Central Fairfax County in northern Virginia...
  The City of Alexandria in northern Virginia...
  The City of Falls Church in northern Virginia...

* Until 615 PM EDT.

* At 314 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 0.5 and 1 inch of rain 
  has 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...                       Alexandria...
  Annandale...                       Springfield...
  Groveton...                        Falls Church...
  Huntington...                      Coral Hills...
  Crystal City...                    Rosslyn...
  Reagan National Airport...         Nationals Park...
  Howard University...               Gallaudet University...
  Fort Totten...                     RFK Stadium...
  Lincolnia...                       Franconia...
  Hybla Valley...                    Merrifield...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3890 7717 3899 7704 3889 7691 3875 7710
      3886 7724

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

KJP
2 follow-up statements
355 
WGUS71 KLWX 012120
FFSLWX

Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
520 PM EDT Thu Jul 1 2021

DCC001-VAC013-059-510-610-012215-
/O.CON.KLWX.FF.W.0018.000000T0000Z-210701T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Arlington VA-Fairfax VA-City of Alexandria
VA-City of Falls Church VA-
520 PM EDT Thu Jul 1 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 615 PM EDT THIS 
EVENING FOR ARLINGTON AND EAST CENTRAL FAIRFAX COUNTIES AND THE 
DISTRICT OF COLUMBIA, THE CITY OF ALEXANDRIA AND THE CITY OF FALLS 
CHURCH...

At 520 PM EDT, Doppler radar indicated that rainfall amounts of 1 to 
2 inches fell within an hour. Excess runoff from the heavy rainfall 
has led to high water on some roadways.

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...
Annandale...                       Springfield...
Groveton...                        Falls Church...
Huntington...                      Coral Hills...
Crystal City...                    Rosslyn...
Reagan National Airport...         Nationals Park...
Howard University...               Gallaudet University...
Fort Totten...                     RFK Stadium...
Lincolnia...                       Franconia...
Hybla Valley...                    Merrifield...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood 
deaths occur in vehicles.

&&

LAT...LON 3890 7717 3899 7704 3889 7691 3875 7710
      3886 7724

FLASH FLOOD...RADAR INDICATED
FLASH FLOOD DAMAGE THREAT...CONSIDERABLE

$$

BJL
100 
WGUS71 KLWX 012214
FFSLWX

Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
614 PM EDT Thu Jul 1 2021

DCC001-VAC013-059-510-610-012224-
/O.EXP.KLWX.FF.W.0018.000000T0000Z-210701T2215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
District of Columbia DC-Arlington VA-Fairfax VA-City of Alexandria
VA-City of Falls Church VA-
614 PM EDT Thu Jul 1 2021

...FLASH FLOOD WARNING WILL EXPIRE AT 615 PM EDT THIS EVENING FOR 
ARLINGTON AND EAST CENTRAL FAIRFAX COUNTIES AND THE DISTRICT OF 
COLUMBIA, THE CITY OF ALEXANDRIA AND THE CITY OF FALLS CHURCH...

Flood waters have receded. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

A Flash Flood Watch remains in effect until 800 AM EDT Friday for 
portions of DC, Maryland and Virginia.

LAT...LON 3890 7717 3899 7704 3889 7691 3875 7710
      3886 7724

$$

BJL

The office that day

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

IssuedProductOfficeCountiesLasted
Jul 1, 1:03 PM EDTSevere Thunderstorm WarningLWX42 min
Jul 1, 1:44 PM EDTSevere Thunderstorm WarningLWX46 min
Jul 1, 2:43 PM EDTSevere Thunderstorm WarningLWX47 min
Jul 1, 1:08 PM EDTSpecial Marine WarningLWX97 min
Jul 1, 1:36 PM EDTSpecial Marine WarningLWX54 min
Jul 1, 1:36 PM EDTSevere Thunderstorm WarningLWXSpotsylvania, Stafford, City of Fredericksburg39 min
Jul 1, 1:47 PM EDTSevere Thunderstorm WarningLWXSpotsylvania43 min
Jul 1, 1:53 PM EDTSevere Thunderstorm WarningLWXLoudoun52 min
Jul 1, 2:11 PM EDTSevere Thunderstorm WarningLWXCulpeper, Fairfax, Fauquier, Loudoun, Prince William, Stafford and 2 more49 min
Jul 1, 2:13 PM EDTSpecial Marine WarningLWX92 min
Jul 1, 2:21 PM EDTSpecial Marine WarningLWX84 min
Jul 1, 2:25 PM EDTSevere Thunderstorm WarningLWXKing George19 min
Jul 1, 2:28 PM EDTSpecial Marine WarningLWX102 min
Jul 1, 2:28 PM EDTSevere Thunderstorm WarningLWXFairfax, Loudoun47 min
Jul 1, 2:50 PM EDTSpecial Marine WarningLWX115 min
Jul 1, 3:00 PM EDTSpecial Marine WarningLWX2 hr
Jul 1, 3:31 PM EDTFlash Flood WarningLWXFairfax, City of Fairfax, City of Falls Church3 hr
Jul 1, 3:32 PM EDTSpecial Marine WarningLWX70 min
Jul 1, 4:52 PM EDTSpecial Marine WarningLWX73 min
Jul 1, 5:23 PM EDTSpecial Marine WarningLWX41 min
Jul 1, 6:10 PM EDTSpecial Marine WarningLWX95 min
Jul 1, 7:29 PM EDTSmall Craft AdvisoryLWX14 hr
Jul 1, 7:29 PM EDTSmall Craft AdvisoryLWX48 hr
Jul 1, 7:37 PM EDTAreal Flood WarningLWXShenandoah, Warren2 hr

Nearby

Flash Flood Warnings in Virginia, 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.