Alert archive / Tennessee / Flash Flood Warnings in 1990

Flash Flood Warning 54, NWS Atlanta, GA

March 17, 1990Polk County, Tennessee

NWS Atlanta, GA issued this flash flood warning at Mar 17, 1990, 6:35 AM EST for Polk County, Tennessee. It was in force for 5 hr.

The area

The counties it named.

The facts

Issued
Mar 17, 1990, 6:35 AM EST (11:35 UTC)
Expired
Mar 17, 1990, 11:30 AM EST
In force
5 hr
Issued by
NWS Atlanta, GA
Area
Whole counties

County Polk County, TN

The radar

The WSR-88D network and its archive begin in 1991, so there is no radar volume for this alert.

The nearest sounding before it

Athens Municipal, GA (KAHN), launched 00:00Z, 11.6 hours before the alert went out and 172 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, Athens Municipal, GA at 00:00Z on 1990-03-17Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 60 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Athens Municipal, GA at 00:00Z on 1990-03-17The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 428 square meters per square second.1939587897Sfc1 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
60 J/kg
Mixed-layer CIN
-108 J/kg
Mixed-layer LCL
953 m above ground
0-6 km bulk shear
77 kt
0-1 km storm-relative helicity
428 m²/s²
0-3 km storm-relative helicity
525 m²/s²
Significant tornado parameter
0.0
Supercell composite
1.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000 
TTAA00 KCHA 171137
FFWCHA
TNC139-171630-
 
BULLETIN - EBS ACTIVATION REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE CHATTANOOGA TENNESSEE
635 AM EST SAT MAR 17 1990
 
THE NATIONAL WEATHER SERVICE IN CHATTANOOGA TENNESSEE HAS ISSUED A
FLASH FLOOD WARNING EFFECTIVE UNTIL 1130 AM EST
FOR PEOPLE IN THE FOLLOWING LOCATIONS
 
IN SOUTHEAST TENNESSEE
 
   ...POLK COUNTY
 
AT 630AM THE OCOEE RIVER IN COPPERHILL WAS SPREADING OVER ITS BANK AND
STARTING TO FLOW INTO STREETS. EVACUATIONS ARE STARTING AT THIS TIME.
 
 
A FLASH FLOOD WARNING MEANS THAT FLOODING IS OCCURRING OR IS
IMMINENT.  MOST FLASH FLOOD DEATHS OCCUR IN AUTOMOBILES.  DO NOT
ATTEMPT TO CROSS BRIDGES...DIPS...OR LOW SPOTS IF WATER COVERS
~THE ROADWAY.  NEVER TRY TO CROSS A FLOWING STREAM...EVEN A SMALL
ONE...ON FOOT.  TO ESCAPE RISING WATER MOVE UP TO HIGHER GROUND.

Nearby

Flash Flood Warnings in Tennessee, 1990Every flash flood warning in 1990

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.