Alert archive / Louisiana / Flash Flood Warnings in 1998

Flash Flood Warning 49, NWS New Orleans, LA

October 6, 19985 parishes in Louisiana

NWS New Orleans, LA issued this flash flood warning at Oct 6, 1998, 8:21 PM CDT for 5 parishes in Louisiana. It was in force for 3 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Oct 6, 1998, 8:21 PM CDT (01:21 UTC)
Expired: Oct 6, 1998, 11:15 PM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Whole counties

Counties Ascension Parish, LA, Assumption Parish, LA, Lafourche Parish, LA, Saint James Parish, LA, Terrebonne Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 1.4 hours before the alert went out and 118 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: 446 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 892 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 106 m²/s²
0-3 km storm-relative helicity: 119 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 3.8

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KNEW 070118
FFWNEW
LAC005-007-057-063-091-093-105-109-070415-

URBAN AND SMALL STREAM FLOOD ADVISORY
NATIONAL WEATHER SERVICE NEW ORLEANS LA
821 PM CDT TUE OCT 6 1998

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS LA HAS ISSUED A...

* URBAN AND SMALL STREAM FLOOD ADVISORY FOR
   - ST HELENA PARISH IN SOUTHEASTERN LOUISIANA
   - LIVINGSTON PARISH IN SOUTHEASTERN LOUISIANA
   - TANGIPAHOA PARISH IN SOUTHEASTERN LOUISIANA
   - ASCENSION PARISH IN SOUTHEASTERN LOUISIANA
   - ASSUMPTION PARISH IN SOUTHEASTERN LOUISIANA
   - ST JAMES PARISH IN SOUTHEASTERN LOUISIANA
   - TERREBONNE PARISH IN SOUTHEASTERN LOUISIANA
   - LAFOURCHE PARISH IN SOUTHEASTERN LOUISIANA

* UNTIL 1115 PM CDT

* AT 800 PM CDT NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED
  AREAS OF HEAVY RAINFALL OVER PARISHES WEST OF THE NEW ORLEANS
  METRO AREA.

  RADAR ESTIMATED 3 INCHES OF RAINFALL IN THE PAST 2-3 HOURS OVER
  NORTHERN TANGIPAHOA..PARTS OF ST HELENA..WESTERN LIVINGSTON..PARTS
  OF ASCENSION..ASSUMPTION AND ST JAMES PARISHES AS WELL AS
  NORTHWEST LAFOURCHE AND WESTERN TERREBONNE PARISHES. THIS
  RAINFALL WILL LIKELY CAUSE EXTENSIVE STREET FLOODING AND
  FLOODING OF LOW LYING AREAS.

DO NOT DRIVE YOUR VEHICLE INTO AREAS WHERE THE WATER COVERS THE
ROADWAY.  THE WATER DEPTH MAY BE TOO GREAT TO ALLOW YOUR CAR TO
CROSS SAFELY.  VEHICLES CAUGHT IN RISING WATER SHOULD BE
ABANDONED QUICKLY.  MOVE TO HIGHER GROUND.

The office that day

Everything else NWS New Orleans, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Oct 6, 7:04 PM CDT	Severe Thunderstorm Warning	LIX	Ascension	46 min
Oct 6, 8:21 PM CDT	Flash Flood Warning	LIX	Livingston, Saint Helena, Tangipahoa	3 hr
Oct 6, 9:26 PM CDT	Severe Thunderstorm Warning	LIX	Washington	44 min

Nearby

Flash Flood Warnings in Louisiana, 1998 Every flash flood warning in 1998

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.