Alert archive / Tennessee / Flash Flood Warnings in 2021

Flash Flood Warning 82, NWS Memphis, TN

August 19, 2021Shelby County, Tennessee

NWS Memphis, TN issued this flash flood warning at Aug 19, 2021, 6:26 PM CDT for Shelby County, Tennessee. It was in force for 100 min. 2 reports 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 19, 2021, 6:26 PM CDT (23:26 UTC)
Expired
Aug 19, 2021, 8:06 PM CDT
In force
100 min
Issued by
NWS Memphis, TN
Area
Storm-based polygon
Flood severity
None

County Shelby County, TN

The radar

The Memphis radar (KNQA), 35 km from the middle of the area, began a volume at 23:27 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

TimeReportWhereRemark
Aug 19, 6:30 PM CDTFLASH FLOOD1 Wnw Collierville, TNESTIMATED 1 FOOT OF WATER COVERING BYHALIA ROAD SOUTH OF W POWELL ROAD.
Aug 19, 6:50 PM CDTFLASH FLOODCollierville, TNAT LEAST 6 INCHES OF WATER COVERING KING RIDGE DRIVE BETWEEN SIX CROWNS STREET AND KING RIDGE COVE.

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

The nearest sounding before it

Little Rock, AR (KLZK), launched 12:00Z, 11.4 hours before the alert went out and 34 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, Little Rock, AR at 12:00Z on 2021-08-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 319 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, Little Rock, AR at 12:00Z on 2021-08-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 40 square meters per square second.1939Sfc1 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
319 J/kg
Mixed-layer CIN
-86 J/kg
Mixed-layer LCL
839 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
40 m²/s²
0-3 km storm-relative helicity
52 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

843 
WGUS54 KMEG 192326
FFWMEG
TNC157-200215-
/O.NEW.KMEG.FF.W.0082.210819T2326Z-210820T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Memphis TN
626 PM CDT Thu Aug 19 2021

The National Weather Service in Memphis has issued a

* Flash Flood Warning for...
  Southeastern Shelby County in western Tennessee...

* Until 915 PM CDT.

* At 626 PM CDT, Doppler radar indicated thunderstorms producing 
  heavy rain across the warned area. Between 1 and 2 inches of rain 
  have fallen. Additional rainfall amounts of 1 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...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...
  Collierville, Germantown, Memphis, Piperton and White Station.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

&&

LAT...LON 3500 8968 3509 8994 3515 8991 3511 8964
      3510 8964 3507 8964 3504 8964 3500 8964

FLASH FLOOD...RADAR INDICATED

$$
1 follow-up statement
293 
WGUS74 KMEG 200106
FFSMEG

Flash Flood Statement
National Weather Service Memphis TN
806 PM CDT Thu Aug 19 2021

TNC157-200116-
/O.CAN.KMEG.FF.W.0082.000000T0000Z-210820T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Shelby TN-
806 PM CDT Thu Aug 19 2021

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

LAT...LON 3500 8968 3509 8994 3515 8991 3511 8964
      3510 8964 3507 8964 3504 8964 3500 8964

$$

SGW

The office that day

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

IssuedProductOfficeCountiesLasted
Aug 19, 6:10 PM CDTAreal Flood AdvisoryMEGShelby16 min

Nearby

Flash Flood Warnings in Tennessee, 2021Every 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.