Alert archive / Tennessee / Flash Flood Warnings in 2021

Flash Flood Warning 29, NWS Morristown, TN

July 9, 2021Knox County, Tennessee

NWS Morristown, TN issued this flash flood warning at Jul 9, 2021, 4:12 PM EDT for Knox County, Tennessee. It was in force for 111 min. 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: Jul 9, 2021, 4:12 PM EDT (20:12 UTC)
Expired: Jul 9, 2021, 6:03 PM EDT
In force: 111 min
Issued by: NWS Morristown, TN
Area: Storm-based polygon
Flood severity: None

County Knox County, TN

The radar

The Knoxville radar (KMRX), 42 km from the middle of the area, began a volume at 20:12 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
Jul 9, 4:39 PM EDT	FLASH FLOOD	Halls, TN	FLOODING OCCURRING AT MAYNARDVILLE PIKE AND NORRIS FREEWAY INTERSECTION IN KNOXVILLE, TN.

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 12:00Z, 8.2 hours before the alert went out and 247 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: 1159 J/kg
Mixed-layer CIN: -27 J/kg
Mixed-layer LCL: 690 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 53 m²/s²
0-3 km storm-relative helicity: 69 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.4

Open this sounding in Storm Lab

The text

As transmitted.

012 
WGUS54 KMRX 092012
FFWMRX
TNC093-092315-
/O.NEW.KMRX.FF.W.0029.210709T2012Z-210709T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Morristown TN
412 PM EDT Fri Jul 9 2021

The National Weather Service in Morristown has issued a

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

* Until 715 PM EDT.

* At 412 PM EDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 2 and 2.5 inches of 
  rain have fallen in the last hour and thunderstorms continue to 
  build over these same areas. Additionally, reports of water over 
  roads have already come in along Brown Gap road just northeast of 
  Fountain City. 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...
  Knoxville, Halls, Maloneyville and Mascot.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3609 8396 3613 8393 3608 8377 3605 8369
      3600 8374 3602 8384 3605 8392

FLASH FLOOD...RADAR INDICATED

$$

CD

1 follow-up statement

310 
WGUS74 KMRX 092203
FFSMRX

Flash Flood Statement
National Weather Service Morristown TN
603 PM EDT Fri Jul 9 2021

TNC093-092213-
/O.CAN.KMRX.FF.W.0029.000000T0000Z-210709T2315Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Knox TN-
603 PM EDT Fri Jul 9 2021

...FLASH FLOOD WARNING IS CANCELLED FOR NORTHEASTERN KNOX COUNTY...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat. Please continue to heed remaining road closures.

LAT...LON 3609 8396 3613 8393 3608 8377 3605 8369
      3600 8374 3602 8384 3605 8392

$$

CD

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 9:30 AM EDT	Special Weather Statement	MRX	Blount, McMinn, Monroe	45 min
Jul 9, 9:51 AM EDT	Areal Flood Advisory	MRX	Bledsoe	114 min
Jul 9, 9:54 AM EDT	Areal Flood Advisory	MRX	Loudon, Monroe	2 hr
Jul 9, 10:00 AM EDT	Special Weather Statement	MRX	Bradley	45 min
Jul 9, 10:54 AM EDT	Special Weather Statement	MRX	Hamilton, Marion, Sequatchie	51 min
Jul 9, 11:25 AM EDT	Special Weather Statement	MRX	Bradley	35 min
Jul 9, 11:31 AM EDT	Areal Flood Advisory	MRX	Hamilton, Marion	119 min
Jul 9, 11:56 AM EDT	Special Weather Statement	MRX	Bradley, Polk	34 min
Jul 9, 12:24 PM EDT	Areal Flood Advisory	MRX	Bradley, Polk	3 hr
Jul 9, 12:35 PM EDT	Special Weather Statement	MRX	Polk	40 min
Jul 9, 2:41 PM EDT	Special Weather Statement	MRX	Washington	49 min
Jul 9, 3:25 PM EDT	Areal Flood Advisory	MRX	Bledsoe	2 hr
Jul 9, 3:46 PM EDT	Special Weather Statement	MRX	Knox	29 min

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.