Alert archive / Tennessee / Flash Flood Warnings in 2021

Flash Flood Warning 57, NWS Nashville, TN

August 21, 2021Lewis County, Marshall County, Maury County, Tennessee

NWS Nashville, TN issued this flash flood warning at Aug 21, 2021, 7:43 PM CDT for Lewis County, Marshall County, Maury County, Tennessee. It was in force for 3 hr. 1 report 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 21, 2021, 7:43 PM CDT (00:43 UTC)
Expired: Aug 21, 2021, 10:45 PM CDT
In force: 3 hr
Issued by: NWS Nashville, TN
Area: Storm-based polygon
Flood severity: None

Counties Lewis County, TN, Marshall County, TN, Maury County, TN

The radar

The Nashville radar (KOHX), 95 km from the middle of the area, began a volume at 00:46 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 21, 8:28 PM CDT	FLASH FLOOD	Columbia, TN	SEVERAL ROADS FLOODED ACROSS MAURY COUNTY INCLUDING SNOW CREEK AT MINGO BRANCH...WILLIAMSPORT PIKE...LYNN CIRCLE...SNOW CREEK ROAD AT MERCANTILE...2635 ROY DODSON RD...AND ROBERTS BEND AT HIGHWAY 7

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The nearest sounding before it

Nashville Metro, TN (KBNA), launched 00:00Z, 0.7 hours before the alert went out and 83 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: 239 J/kg
Mixed-layer CIN: -69 J/kg
Mixed-layer LCL: 947 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 69 m²/s²
0-3 km storm-relative helicity: 60 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

As transmitted.

327 
WGUS54 KOHX 220043
FFWOHX
TNC101-117-119-220345-
/O.NEW.KOHX.FF.W.0057.210822T0043Z-210822T0345Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Nashville TN
743 PM CDT Sat Aug 21 2021

The National Weather Service in Nashville has issued a

* Flash Flood Warning for...
  Northeastern Lewis County in middle Tennessee...
  West Central Marshall County in middle Tennessee...
  Southern Maury County in middle Tennessee...

* Until 1045 PM CDT.

* At 743 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Flash flooding is ongoing or 
  expected to begin shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  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...
  Green Lick Creek, Big Bigby and Little Bigby Creek, Scotts Creek, 
  and areas near Columbia, Mount Pleasant, Culleoka, Williamsport 
  and Hampshire.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3556 8732 3559 8739 3563 8739 3569 8723
      3559 8680 3540 8685 3543 8706 3544 8709

FLASH FLOOD...RADAR INDICATED

$$

LaRosa

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 21, 7:03 PM CDT	Areal Flood Advisory	OHX	Giles, Hickman, Lawrence, Lewis, Marshall, Maury and 1 more	4 hr
Aug 21, 7:22 PM CDT	Special Weather Statement	OHX	Maury	38 min
Aug 21, 7:24 PM CDT	Flash Flood Warning	OHX	Marshall, Maury, Williamson	4 hr
Aug 21, 9:11 PM CDT	Areal Flood Advisory	OHX	Bedford, Cannon, Coffee, Marshall, Rutherford, Warren	3 hr
Aug 21, 9:59 PM CDT	River Flood Advisory	OHX	Hickman	14 hr
Aug 21, 10:34 PM CDT	Areal Flood Advisory	OHX	Dickson, Hickman, Houston, Humphreys	10 hr
Aug 22, 12:33 AM CDT	River Flood Advisory	OHX	Lawrence	6 hr

Nearby

Flash Flood Warnings in Tennessee, 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.