Alert archive / Tennessee / Flash Flood Watches in 2021

Flash Flood Watch 6, NWS Nashville, TN

August 20, 202116 counties in Tennessee

NWS Nashville, TN issued this flash flood watch at Aug 20, 2021, 4:55 PM CDT for 16 counties in Tennessee. It took effect at Aug 21, 2021, 1:00 AM CDT. It was in force for 22 hr.

The area

The counties it named.

The facts

Issued
Aug 20, 2021, 4:55 PM CDT (21:55 UTC)
In effect from
Aug 21, 2021, 1:00 AM CDT
Expired
Aug 21, 2021, 10:47 PM CDT
In force
22 hr
Issued by
NWS Nashville, TN
Flood severity
None

Counties Bedford County, TN, Cheatham County, TN, Dickson County, TN, Giles County, TN, Hickman County, TN, Houston County, TN, Humphreys County, TN, Lawrence County, TN, Lewis County, TN, Marshall County, TN, Maury County, TN, Montgomery County, TN, Perry County, TN, Stewart County, TN, Wayne County, TN, Williamson County, TN

The radar

The Nashville radar (KOHX), 85 km from the middle of the area, began a volume at 21:58 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

Nashville Metro, TN (KBNA), launched 12:00Z, 9.9 hours before the alert went out and 76 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, Nashville Metro, TN at 12:00Z on 2021-08-20Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 892 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Nashville Metro, TN at 12:00Z on 2021-08-20The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 18 square meters per square second.19395878Sfc1 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
892 J/kg
Mixed-layer CIN
-10 J/kg
Mixed-layer LCL
556 m above ground
0-6 km bulk shear
19 kt
0-1 km storm-relative helicity
18 m²/s²
0-3 km storm-relative helicity
66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

691 
WGUS64 KOHX 202155
FFAOHX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Nashville TN
455 PM CDT Fri Aug 20 2021

TNZ005-006-023>026-056>061-075-093>095-211800-
/O.NEW.KOHX.FF.A.0006.210821T0600Z-210821T1800Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Stewart-Montgomery-Houston-Humphreys-Dickson-Cheatham-Perry-Hickman-
Lewis-Williamson-Maury-Marshall-Bedford-Wayne-Lawrence-Giles-
Including the cities of McEwen, Clarksville, Pulaski, Linden, 
Waverly, Columbia, Brentwood, Kingston Springs, Ashland City, 
Dickson, Waynesboro, New Johnsonville, Franklin, Lewisburg, 
Tennessee Ridge, Dover, Lawrenceburg, Lobelville, Clifton, Erin, 
Hohenwald, Centerville, and Shelbyville
455 PM CDT Fri Aug 20 2021

...FLASH FLOOD WATCH IN EFFECT FROM 1 AM CDT SATURDAY THROUGH 
SATURDAY AFTERNOON...

The National Weather Service in Nashville has issued a

* Flash Flood Watch for a portion of Middle Tennessee, including the 
  following areas, Bedford, Cheatham, Dickson, Giles, Hickman, 
  Houston, Humphreys, Lawrence, Lewis, Marshall, Maury, Montgomery, 
  Perry, Stewart, Wayne and Williamson.

* From 1 AM CDT Saturday through Saturday afternoon.

* 2 To 5 inches of rain have fallen across many locations in the 
  watch area over the past few days. Additional showers and 
  thunderstorms are expected to develop after midnight tonight 
  through the morning hours Saturday, resulting in an additional 2 
  to 4 inches of rain possible. Higher amounts may be possible with 
  training of heavier showers and storms.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Barnwell
4 follow-up statements
842 
WGUS64 KOHX 210640
FFAOHX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Nashville TN
140 AM CDT Sat Aug 21 2021

TNZ005-006-023>026-056>061-075-093>095-211445-
/O.EXT.KOHX.FF.A.0006.000000T0000Z-210821T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Stewart-Montgomery-Houston-Humphreys-Dickson-Cheatham-Perry-Hickman-
Lewis-Williamson-Maury-Marshall-Bedford-Wayne-Lawrence-Giles-
Including the cities of McEwen, Clarksville, Pulaski, Linden, 
Waverly, Columbia, Brentwood, Kingston Springs, Ashland City, 
Dickson, Waynesboro, New Johnsonville, Franklin, Lewisburg, 
Tennessee Ridge, Dover, Lawrenceburg, Lobelville, Clifton, Erin, 
Hohenwald, Centerville, and Shelbyville
140 AM CDT Sat Aug 21 2021

...FLASH FLOOD WATCH NOW IN EFFECT THROUGH 3 PM CDT THIS AFTERNOON...

The Flash Flood Watch is now in effect for

* A portion of Middle Tennessee, including the following areas, 
  Bedford, Cheatham, Dickson, Giles, Hickman, Houston, Humphreys, 
  Lawrence, Lewis, Marshall, Maury, Montgomery, Perry, Stewart, 
  Wayne and Williamson.

* Through this afternoon.

* 2 To 5 inches of rain have fallen across many locations in the 
  watch area over the past few days. Additional showers and 
  thunderstorms are expected to develop after midnight tonight 
  through the morning hours Saturday, resulting in an additional 2 
  to 4 inches of rain possible. Higher amounts may be possible with 
  training of heavier showers and storms.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

07
449 
WGUS64 KOHX 211500
FFAOHX

Flood Watch
National Weather Service Nashville TN
1000 AM CDT Sat Aug 21 2021

TNZ005-006-023>026-056>061-075-093>095-212000-
/O.CON.KOHX.FF.A.0006.000000T0000Z-210821T2000Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Stewart-Montgomery-Houston-Humphreys-Dickson-Cheatham-Perry-Hickman-
Lewis-Williamson-Maury-Marshall-Bedford-Wayne-Lawrence-Giles-
Including the cities of McEwen, Clarksville, Pulaski, Linden, 
Waverly, Columbia, Brentwood, Kingston Springs, Ashland City, 
Dickson, Waynesboro, New Johnsonville, Franklin, Lewisburg, 
Tennessee Ridge, Dover, Lawrenceburg, Lobelville, Clifton, Erin, 
Hohenwald, Centerville, and Shelbyville
1000 AM CDT Sat Aug 21 2021

...FLASH FLOOD WATCH REMAINS IN EFFECT UNTIL 3 PM CDT THIS 
AFTERNOON...

The Flash Flood Watch continues for

* A portion of Middle Tennessee, including the following areas, 
  Bedford, Cheatham, Dickson, Giles, Hickman, Houston, Humphreys, 
  Lawrence, Lewis, Marshall, Maury, Montgomery, Perry, Stewart, 
  Wayne and Williamson.

* Until 3 PM CDT this afternoon.

* A total of 6 to 12 inches of rain has already fallen in portions 
  of the Flash Flood Watch causing catastrophic flooding including 
  closed and washed out roads, water rescues, and homes and business 
  inundated with water.  Another 2 to possibly 4 inches of rain is 
  expected in portions of the watch area.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Hurley
038 
WGUS64 KOHX 211932
FFAOHX

URGENT - IMMEDIATE BROADCAST REQUESTED
Flood Watch
National Weather Service Nashville TN
232 PM CDT Sat Aug 21 2021

TNZ005-006-023>026-056>061-075-093>095-220500-
/O.EXT.KOHX.FF.A.0006.000000T0000Z-210822T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Stewart-Montgomery-Houston-Humphreys-Dickson-Cheatham-Perry-Hickman-
Lewis-Williamson-Maury-Marshall-Bedford-Wayne-Lawrence-Giles-
Including the cities of McEwen, Clarksville, Pulaski, Linden, 
Waverly, Columbia, Brentwood, Kingston Springs, Ashland City, 
Dickson, Waynesboro, New Johnsonville, Franklin, Lewisburg, 
Tennessee Ridge, Dover, Lawrenceburg, Lobelville, Clifton, Erin, 
Hohenwald, Centerville, and Shelbyville
232 PM CDT Sat Aug 21 2021

...FLASH FLOOD WATCH NOW IN EFFECT UNTIL MIDNIGHT CDT TONIGHT...

The Flash Flood Watch is now in effect for

* A portion of Middle Tennessee, including the following areas, 
  Bedford, Cheatham, Dickson, Giles, Hickman, Houston, Humphreys, 
  Lawrence, Lewis, Marshall, Maury, Montgomery, Perry, Stewart, 
  Wayne and Williamson.

* Until Midnight CDT tonight.

* A total of 8 to 14 inches of rain has fallen in portions of the 
  Flash Flood Watch, causing catastrophic flooding. Flash flooding 
  has washed out roads, inundated homes and businesses, and led to 
  numerous water rescues. Storms that redevelop over similar 
  locations this evening could produce an additional 1 to 2 inches 
  with locally higher amounts. Additional rainfall in areas where 
  significant flooding is still occurring will exacerbate the flash 
  flood threat.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

You should monitor later forecasts and be prepared to take action 
should Flash Flood Warnings be issued.

&&

$$

Schaper
824 
WGUS64 KOHX 220347
FFAOHX

Flood Watch
National Weather Service Nashville TN
1047 PM CDT Sat Aug 21 2021

TNZ005-006-023>026-056>061-075-093>095-220500-
/O.CAN.KOHX.FF.A.0006.000000T0000Z-210822T0500Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Stewart-Montgomery-Houston-Humphreys-Dickson-Cheatham-Perry-Hickman-
Lewis-Williamson-Maury-Marshall-Bedford-Wayne-Lawrence-Giles-
Including the cities of McEwen, Clarksville, Pulaski, Linden, 
Waverly, Columbia, Brentwood, Kingston Springs, Ashland City, 
Dickson, Waynesboro, New Johnsonville, Franklin, Lewisburg, 
Tennessee Ridge, Dover, Lawrenceburg, Lobelville, Clifton, Erin, 
Hohenwald, Centerville, and Shelbyville
1047 PM CDT Sat Aug 21 2021

...FLASH FLOOD WATCH IS CANCELLED...

The Flash Flood Watch for a portion of Middle Tennessee, including 
the following areas, Bedford, Cheatham, Dickson, Giles, Hickman, 
Houston, Humphreys, Lawrence, Lewis, Marshall, Maury, Montgomery, 
Perry, Stewart, Wayne and Williamson has been cancelled.

Additional rainfall is not expected overnight, but ponding on roads 
and standing water will remain for many areas into Sunday. Creeks, 
streams, and rivers will likely remain elevated overnight and into 
Sunday, but will slowly recede. Please continue to heed remaining 
road closures.

$$

Barnwell

The office that day

Everything else NWS Nashville, TN issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 19, 7:17 PM CDTAreal Flood AdvisoryOHXLawrence3 hr

Nearby

Flash Flood Watches in Tennessee, 2021Every flash flood watch 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.