Alert archive / Louisiana / Flash Flood Warnings in 1998

Flash Flood Warning 30, NWS New Orleans, LA

September 12, 1998Ascension Parish, Assumption Parish, Saint James Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Sep 12, 1998, 6:31 AM CDT for Ascension Parish, Assumption Parish, Saint James Parish, 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: Sep 12, 1998, 6:31 AM CDT (11:31 UTC)
Expired: Sep 12, 1998, 9:25 AM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Whole counties

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

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 00:00Z, 11.5 hours before the alert went out and 120 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: 72 J/kg
Mixed-layer CIN: -21 J/kg
Mixed-layer LCL: 747 m above ground
0-6 km bulk shear: 30 kt
0-1 km storm-relative helicity: 164 m²/s²
0-3 km storm-relative helicity: 276 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KNEW 121131
FFWNEW
LAC005-007-057-093-109-121425-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
631 AM CDT SAT SEP 12 1998

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

* FLASH FLOOD WARNING FOR
   - 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 925 AM CDT

* NATIONAL WEATHER SERVICE RADAR INDICATED A BROAD BAND OF MODERATE
  TO HEAVY RAIN MOVING SLOWLY EAST ACROSS THE PARISHES FROM
  DONALDSONVILE SOUTH TO HOUMA AND INTO THE GULF. THIS AREA OF
  MODERATE TO HEAVY RAIN DRIFTING EAST ABOUT 5 TO 10 MILES AN
  HOUR. RADAR RAINFALL RATES RANGE FROM 2 TO 3 INCHES PER HOUR.
  DURING THE PAST 3 HOURS OVER 4 INCHES OF RAIN HAS FALLEN.
  SHERIFFS OFFICES IN ASSUMPTION AND ASCENSION PARISHES REPORTED
  VERY HEAVY RAIN DURING THE PAST TWO HOURS WITH WATER OVER MANY
  ROADS AND HIGHWAYS WITH SOME ROADWAYS CLOSED DUE TO HIGH WATER
  AND OTHERS NEARLY IMPASSABLE.  PERSONS ARE ADVISED TO STAY
  HOME AND AVOID TRAVELING IF POSSIBLE.

 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
Sep 12, 6:31 AM CDT	Flash Flood Warning	LIX	Lafourche, Terrebonne	3 hr
Sep 12, 8:48 AM CDT	Flash Flood Warning	LIX	Orleans, Plaquemines, Saint Bernard	2 hr
Sep 12, 8:48 AM CDT	Flash Flood Warning	LIX	Jefferson, Saint Charles, Saint John the Baptist	2 hr
Sep 12, 11:03 AM CDT	Flash Flood Warning	LIX	Saint Tammany	3 hr
Sep 12, 11:03 AM CDT	Flash Flood Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	3 hr
Sep 12, 1:28 PM CDT	Flash Flood Warning	LIX	Plaquemines	3 hr

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.