Alert archive / Virginia / Flash Flood Warnings in 2021

Flash Flood Warning 28, NWS Baltimore/Washington

July 24, 2021Nelson County, Virginia

NWS Baltimore/Washington issued this flash flood warning at Jul 24, 2021, 10:29 PM EDT for Nelson County, Virginia. It was in force for 91 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued: Jul 24, 2021, 10:29 PM EDT (02:29 UTC)
Expired: Jul 25, 2021, 12:00 AM EDT
In force: 91 min
Issued by: NWS Baltimore/Washington
Area: Storm-based polygon
Flood severity: None

County Nelson County, VA

The radar

The Roanoke radar (KFCX), 156 km from the middle of the area, began a volume at 02:31 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

Roanoke, VA (KRNK), launched 00:00Z, 2.5 hours before the alert went out and 87 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 565 J/kg
Mixed-layer CIN: -23 J/kg
Mixed-layer LCL: 974 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 32 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.7

Open this sounding in Storm Lab

The text

As transmitted.

762 
WGUS51 KLWX 250229
FFWLWX
VAC125-250530-
/O.NEW.KLWX.FF.W.0028.210725T0229Z-210725T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Baltimore MD/Washington DC
1029 PM EDT Sat Jul 24 2021

The National Weather Service in Sterling Virginia has issued a

* Flash Flood Warning for...
  Southeastern Nelson County in central Virginia...

* Until 130 AM EDT.

* At 1029 PM EDT, Doppler radar indicated heavy rain across the 
  warned area. Between 2 and 6 inches of rain have fallen. 
  Additional rainfall amounts of 0.5 to 1.5 inches are possible in 
  the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by heavy rain.

  SOURCE...Radar.

  IMPACT...Flash flooding of small creeks and streams, urban
           areas, highways, streets and underpasses as well as
           other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Wingina...

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 3764 7877 3768 7883 3773 7874 3770 7866
      3769 7864 3768 7865 3768 7866 3770 7868
      3770 7869 3769 7870 3768 7869 3767 7871
      3766 7872 3764 7871 3764 7872 3763 7874

FLASH FLOOD...RADAR INDICATED

$$

KJP

1 follow-up statement

427 
WGUS71 KLWX 250400
FFSLWX

Flash Flood Statement
National Weather Service Baltimore MD/Washington DC
1200 AM EDT Sun Jul 25 2021

VAC125-250410-
/O.CAN.KLWX.FF.W.0028.000000T0000Z-210725T0530Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Nelson VA-
1200 AM EDT Sun Jul 25 2021

...FLASH FLOOD WARNING FOR SOUTHEASTERN NELSON COUNTY HAS BEEN 
REPLACED WITH A FLOOD WARNING...

Rainfall has begun to exit the area impacted by the prior Flash 
Flood Warning. Some residual flooding concerns may remain where the 
heaviest rainfall occurred.

LAT...LON 3764 7877 3768 7883 3773 7874 3770 7866
      3769 7864 3768 7865 3768 7866 3770 7868
      3770 7869 3769 7870 3768 7869 3767 7871
      3766 7872 3764 7871 3764 7872 3763 7874

$$

BRO

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 25, 12:00 AM EDT	Areal Flood Warning	LWX	Nelson	78 min

Nearby

Flash Flood Warnings in Virginia, 2021 Every 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; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.