Alert archive / Tennessee / Flash Flood Warnings in 2021

Flash Flood Warning 37, NWS Morristown, TN

August 31, 2021Knox County, Tennessee

NWS Morristown, TN issued this flash flood warning at Aug 31, 2021, 6:41 PM EDT for Knox County, Tennessee. It was in force for 2 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 31, 2021, 6:41 PM EDT (22:41 UTC)
Expired: Aug 31, 2021, 9:05 PM EDT
In force: 2 hr
Issued by: NWS Morristown, TN
Area: Storm-based polygon
Flood severity: None

County Knox County, TN

The radar

The Knoxville radar (KMRX), 67 km from the middle of the area, began a volume at 22:43 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 31, 6:51 PM EDT	FLASH FLOOD	Farragut, TN	SOCIAL MEDIA IMAGE OF WATER PONDING IN BACKYARD OF HOME.

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

The nearest sounding before it

Peachtre/Fal Fld, GA (KFFC), launched 12:00Z, 10.7 hours before the alert went out and 284 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: 209 J/kg
Mixed-layer CIN: -42 J/kg
Mixed-layer LCL: 708 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 283 m²/s²
0-3 km storm-relative helicity: 351 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.5

Open this sounding in Storm Lab

The text

As transmitted.

250 
WGUS54 KMRX 312241
FFWMRX
TNC093-010115-
/O.NEW.KMRX.FF.W.0037.210831T2241Z-210901T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Morristown TN
641 PM EDT Tue Aug 31 2021

The National Weather Service in Morristown has issued a

* Flash Flood Warning for...
  Central Knox County in east Tennessee...

* Until 915 PM EDT.

* At 641 PM EDT, local law enforcement reported storms producing 
  heavy rain across the warned area. Up to 2 inches of rain have 
  fallen. Additional rainfall amounts up to 2 inches are possible in 
  the warned area. Flash flooding is ongoing or expected to begin 
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Law enforcement reported.

  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...
  Knoxville, Oak Ridge, Farragut, Louisville, Halls, Bearden, Powell 
  and Karns.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3611 8391 3601 8378 3585 8408 3584 8411
      3583 8412 3585 8413 3585 8414 3584 8415
      3583 8414 3581 8416 3591 8427

FLASH FLOOD...OBSERVED

$$

19

2 follow-up statements

504 
WGUS74 KMRX 010014
FFSMRX

Flash Flood Statement
National Weather Service Morristown TN
814 PM EDT Tue Aug 31 2021

TNC093-010115-
/O.CON.KMRX.FF.W.0037.000000T0000Z-210901T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Knox TN-
814 PM EDT Tue Aug 31 2021

...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 915 PM EDT THIS 
EVENING FOR CENTRAL KNOX COUNTY...

At 814 PM EDT, local law enforcement reported flooding in west 
Knoxville. Up to 2.5 inches of rain have fallen. Even though the 
heaviest rain will be ending soon it will take some time for the 
flood waters to drain away.

HAZARD...Flash flooding caused by heavy rain.

SOURCE...Law enforcement reported.

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...
  Knoxville, Oak Ridge, Farragut, Louisville, Halls, Bearden, Powell 
  and Karns.

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.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 3611 8391 3601 8378 3585 8408 3584 8411
      3583 8412 3585 8413 3585 8414 3584 8415
      3583 8414 3581 8416 3591 8427

FLASH FLOOD...OBSERVED

$$

19

488 
WGUS74 KMRX 010105
FFSMRX

Flash Flood Statement
National Weather Service Morristown TN
905 PM EDT Tue Aug 31 2021

TNC093-010115-
/O.CAN.KMRX.FF.W.0037.000000T0000Z-210901T0115Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Knox TN-
905 PM EDT Tue Aug 31 2021

...FLASH FLOOD WARNING FOR CENTRAL KNOX COUNTY HAS BEEN REPLACED 
WITH A FLOOD ADVISORY...

LAT...LON 3611 8391 3601 8378 3585 8408 3584 8411
      3583 8412 3585 8413 3585 8414 3584 8415
      3583 8414 3581 8416 3591 8427

$$

19

The office that day

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

Issued	Product	Office	Counties	Lasted
Aug 30, 8:01 PM EDT	Special Weather Statement	MRX	Anderson, Campbell, Morgan, Scott	59 min
Aug 30, 8:25 PM EDT	Special Weather Statement	MRX	Grainger, Jefferson, Knox, Sevier, Union	65 min
Aug 30, 8:42 PM EDT	Areal Flood Advisory	MRX	Anderson, Blount, Campbell, Cocke, Grainger, Jefferson and 5 more	2 hr
Aug 31, 9:39 AM EDT	River Flood Warning	MRX	Hamilton	20 hr
Aug 31, 10:23 AM EDT	Areal Flood Advisory	MRX	Bradley, Loudon, McMinn, Monroe, Polk	3 hr
Aug 31, 12:44 PM EDT	Areal Flood Advisory	MRX	Monroe, Polk	9 hr
Aug 31, 2:08 PM EDT	Special Weather Statement	MRX	Sequatchie	22 min
Aug 31, 2:10 PM EDT	Special Weather Statement	MRX	Bradley	20 min
Aug 31, 2:32 PM EDT	Special Weather Statement	MRX	Bledsoe	28 min
Aug 31, 3:07 PM EDT	Special Weather Statement	MRX	Meigs	23 min
Aug 31, 3:23 PM EDT	Special Weather Statement	MRX	Rhea	37 min
Aug 31, 3:48 PM EDT	Special Weather Statement	MRX	Rhea	27 min
Aug 31, 4:43 PM EDT	Areal Flood Advisory	MRX	Hamilton, Marion, Sequatchie	2 hr
Aug 31, 5:16 PM EDT	Areal Flood Advisory	MRX	Knox	85 min
Aug 31, 5:24 PM EDT	Areal Flood Advisory	MRX	McMinn, Monroe, Polk	5 hr
Aug 31, 6:12 PM EDT	Areal Flood Advisory	MRX	Blount, Knox, Loudon, Monroe	4 hr
Aug 31, 6:20 PM EDT	Special Weather Statement	MRX	Carter, Johnson	40 min
Aug 31, 6:53 PM EDT	Areal Flood Advisory	MRX	Anderson, Knox	5 hr
Aug 31, 7:02 PM EDT	Areal Flood Advisory	MRX	Loudon, Monroe, Roane	3 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.