Alert archive / Louisiana / Flash Flood Warnings in 1998

Flash Flood Warning 41, NWS New Orleans, LA

September 18, 1998Saint Charles Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Sep 18, 1998, 1:37 PM CDT for Saint Charles Parish, Louisiana. It was in force for 113 min. 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 18, 1998, 1:37 PM CDT (18:37 UTC)
Expired
Sep 18, 1998, 3:30 PM CDT
In force
113 min
Issued by
NWS New Orleans, LA
Area
Whole counties

County Saint Charles Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 6.6 hours before the alert went out and 74 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, Slidell Radar S, LA at 12:00Z on 1998-09-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 422 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, Slidell Radar S, LA at 12:00Z on 1998-09-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -2 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
422 J/kg
Mixed-layer CIN
-9 J/kg
Mixed-layer LCL
606 m above ground
0-6 km bulk shear
10 kt
0-1 km storm-relative helicity
-2 m²/s²
0-3 km storm-relative helicity
14 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KNEW 181836
FFWNEW
LAC089-182030-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
137 PM CDT FRI SEP 18 1998

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

* FLASH FLOOD WARNING FOR
   - ST CHARLES PARISH IN SOUTHEASTERN LOUISIANA

* UNTIL 330 PM CDT

* AT 130 PM CDT...DOPPLER RADAR INDICATED A THUNDERSTORM PRODUCING
  VERY HEAVY RAIN MOVING SLOWLY THROUGH ST. CHARLES PARISH. DOPPLER
  RADAR ESTIMATES AND ST. CHARLES EOC PERSONNEL INDICATE RAINFALL
  RATES OF TWO TO THREE INCHES PER HOUR WERE OCCURRING.

  SINCE THE GROUND IS ALREADY SATURATED DUE TO HEAVY RAINFALL
  DURING THE PAST WEEK...THE ADDITIONAL RAINFALL WILL LIKELY RESULT
  FLASH FLOODING.

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.

What forecasters said that day

The local office's own words before this flash flood warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

In the hours before

Special weather statement, Sep 18, 11:40 AM CDT, 1 hour 57 minutes before
LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-191730-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1140 AM CDT FRI SEP 18 1998

MOISTURE WILL CONTINUE TO INCREASE ACROSS THE LOCAL REGION UNDER
UNSTABLIZING AIR MASS. AREA COVERAGE OF SHOWERS WILL GRADUALLY
INCREASE THROUGH TONIGHT AND SATURDAY. A FEW THUNDERSTORMS ARE
EXPECTED WITH LOCALLY HEAVY DOWNPOURS THROUGH SATURDAY.
HOWEVER...SEVERE THUNDERSTORMS ARE NOT EXPECTED.
Special weather statement, Sep 18, 11:40 AM CDT, 1 hour 57 minutes before
LAZ034>040-046>050-056>070-MSZ068>071-077-080>082-191730-

THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE NEW ORLEANS LA
1140 AM CDT FRI SEP 18 1998

MOISTURE WILL CONTINUE TO INCREASE ACROSS THE LOCAL REGION UNDER
UNSTABLIZING AIR MASS. AREA COVERAGE OF SHOWERS WILL GRADUALLY
INCREASE THROUGH TONIGHT AND SATURDAY. A FEW THUNDERSTORMS ARE
EXPECTED WITH LOCALLY HEAVY DOWNPOURS THROUGH SATURDAY.
HOWEVER...SEVERE THUNDERSTORMS ARE NOT EXPECTED.

The office that day

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

IssuedProductOfficeCountiesLasted
Sep 18, 3:40 PM CDTFlash Flood WarningLIXJefferson, Plaquemines2 hr
Sep 18, 4:33 PM CDTFlash Flood WarningLIXLafourche, Terrebonne3 hr

Nearby

Flash Flood Warnings in Louisiana, 1998Every 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.