Alert archive / Tennessee / Flash Flood Warnings in 2017

Flash Flood Warning 5, NWS Nashville, TN

April 18, 2017Williamson County, Tennessee

NWS Nashville, TN issued this flash flood warning at Apr 18, 2017, 8:02 PM CDT for Williamson 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: Apr 18, 2017, 8:02 PM CDT (01:02 UTC)
Expired: Apr 18, 2017, 11:15 PM CDT
In force: 3 hr
Issued by: NWS Nashville, TN
Area: Storm-based polygon
Flood severity: None

County Williamson County, TN

The radar

The Nashville radar (KOHX), 49 km from the middle of the area, began a volume at 01:03 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
Apr 18, 8:05 PM CDT	FLASH FLOOD	Fairview, TN	TEMPLE RD...OLD NATCHEZ TR ...AND OLD HILLSBORO RD ARE ALL FLOODED IN PLACES

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, 1.0 hours before the alert went out and 39 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: 366 J/kg
Mixed-layer CIN: -63 J/kg
Mixed-layer LCL: 723 m above ground
0-6 km bulk shear: 23 kt
0-1 km storm-relative helicity: 111 m²/s²
0-3 km storm-relative helicity: 132 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.7

Open this sounding in Storm Lab

The text

As transmitted.

979 
WGUS54 KOHX 190102
FFWOHX
TNC187-190415-
/O.NEW.KOHX.FF.W.0005.170419T0102Z-170419T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Nashville TN
802 PM CDT TUE APR 18 2017

The National Weather Service in Nashville has issued a

* Flash Flood Warning for...
  Northwestern Williamson County in Middle Tennessee...

* Until 1115 PM CDT

* At 801 PM CDT, Doppler radar indicated numerous showers and 
  isolated thunderstorms with the potential of producing additional 
  rainfall moving across northwestern portions of Williamson County 
  that have already experienced saturated ground conditions from 
  rainfall that has occurred over the last three hours. One, to 
  localized amounts in excess of three inches, of rainfall have 
  already occurred across locations southeast of Fairview, with the 
  heaviest amounts generally in the Ferndale area, with lesser 
  amounts down to one inch spreading northeastward to just west of 
  Brentwood. Additional rainfall amounts of one half to around one 
  inch will be possible across this area through the remainder of 
  the evening hours. Thus, flash flooding is expected to begin 
  shortly. 
  
  PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

A Flash Flood Warning means that flooding is imminent or occurring.
If you are in the warned area move to higher ground immediately.
Residents living along streams and creeks should take immediate
precautions to protect life and property.

&&

LAT...LON 3602 8675 3580 8705 3586 8721 3605 8718
      3604 8706 3598 8704 3605 8690

$$
31

1 follow-up statement

474 
WGUS74 KOHX 190257
FFSOHX

Flash Flood Statement
National Weather Service Nashville TN
957 PM CDT TUE APR 18 2017

TNC187-190415-
/O.CON.KOHX.FF.W.0005.000000T0000Z-170419T0415Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Williamson TN-
957 PM CDT TUE APR 18 2017

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 1115 PM CDT FOR
NORTHWESTERN WILLIAMSON COUNTY...

At 957 PM CDT, even though rainfall has ended across northwestern 
Williamson County, runoff potential still remains, and thus the 
flash flood warning will remain in effect until 1115 PM CDT.

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.

&&

LAT...LON 3602 8675 3580 8705 3586 8721 3605 8718
      3604 8706 3598 8704 3605 8690

$$
31

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 18, 7:18 PM CDT	Flash Flood Warning	OHX	Davidson	4 hr
Apr 18, 7:34 PM CDT	Areal Flood Advisory	OHX	Hickman	3 hr
Apr 18, 7:39 PM CDT	Special Weather Statement	OHX	Hickman	21 min

Nearby

Flash Flood Warnings in Tennessee, 2017 Every flash flood warning in 2017

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.