Alert archive / Louisiana / Flash Flood Warnings in 1998

Flash Flood Warning 28, NWS New Orleans, LA

September 11, 1998Plaquemines Parish, Saint Bernard Parish, Louisiana

NWS New Orleans, LA issued this flash flood warning at Sep 11, 1998, 5:15 PM CDT for Plaquemines Parish, Saint Bernard 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 11, 1998, 5:15 PM CDT (22:15 UTC)
Expired: Sep 11, 1998, 8:15 PM CDT
In force: 3 hr
Issued by: NWS New Orleans, LA
Area: Whole counties

Counties Plaquemines Parish, LA, Saint Bernard Parish, LA

The nearest sounding before it

Slidell Radar S, LA (KSIL), launched 12:00Z, 10.3 hours before the alert went out and 61 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: 173 J/kg
Mixed-layer CIN: -30 J/kg
Mixed-layer LCL: 653 m above ground
0-6 km bulk shear: 26 kt
0-1 km storm-relative helicity: 220 m²/s²
0-3 km storm-relative helicity: 353 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.3

Open this sounding in Storm Lab

The text

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

000 
TTAA00 KNEW 112215
FFWNEW
LAC075-087-120115-

BULLETIN - IMMEDIATE BROADCAST REQUESTED
FLASH FLOOD WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
515 PM CDT FRI SEP 11 1998

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

* FLASH FLOOD WARNING FOR
   - ST BERNARD PARISH IN SOUTHEASTERN LOUISIANA
   - PLAQUEMINES PARISH IN SOUTHEASTERN LOUISIANA

* UNTIL 815 PM CDT

* AT 515 PM CDT...DOPPLER RADAR INDICATED ANOTHER AREA OF HEAVY RAIN
  MOVING NORTH ACROSS PLAQUEMINES AND ST. BERNARD PARISHES. RAINFALL
  AMOUNTS OF ONE TO TWO INCHES PER HOUR CAN BE EXPECTED FROM THIS
  BAND OF HEAVY RAIN.

BE ESPECIALLY CAUTIOUS AT NIGHT WHEN IT IS HARDER TO RECOGNIZE
THE DANGERS OF FLOODS AND FLASH FLOODS.  IF FLASH FLOODING IS
OBSERVED...ACT QUICKLY.  MOVE UP TO ESCAPE FLOOD WATERS.  DO
NOT STAY IN AREAS SUBJECT TO FLOODING WHEN WATER BEGINS RISING.

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

Local storm report, Sep 11, 4:52 PM CDT, 23 minutes before

PRELIMINARY LOCAL STORM REPORT...UPDATED INFORMATION...
NATIONAL WEATHER SERVICE OFFICE NEW ORLEANS LOUISIANA

452 PM CDT THU SEP 11 1998

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....PARISH LOCATION....

0540 PM    CUT OFF                   LA   TORNADO
09/10/98   LAFOURCHE                      *** 1 DEAD, 6 INJ ***
                                          A TORNADO CUT A 4 MILE
                                          PATH BETWEEN CUT OFF AND
                                          LAROSE DAMAGING 56
                                          RESIDENCES AND TWO
                                          BUSINESSES.

Local storm report, Sep 11, 4:52 PM CDT, 23 minutes before

PRELIMINARY LOCAL STORM REPORT...UPDATED INFORMATION...
NATIONAL WEATHER SERVICE OFFICE NEW ORLEANS LOUISIANA

452 PM CDT THU SEP 11 1998

TIME(CDT)  .....CITY LOCATION..... STATE  ...EVENT/REMARKS...
           ....PARISH LOCATION....

0540 PM    CUT OFF                   LA   TORNADO
09/10/98   LAFOURCHE                      *** 1 DEAD, 6 INJ ***
                                          A TORNADO CUT A 4 MILE
                                          PATH BETWEEN CUT OFF AND
                                          LAROSE DAMAGING 56
                                          RESIDENCES AND TWO
                                          BUSINESSES.

The office that day

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

Issued	Product	Office	Counties	Lasted
Sep 10, 7:06 PM CDT	Tornado Warning	LIX	Jefferson	29 min
Sep 10, 8:41 PM CDT	Tornado Warning	LIX	Saint Charles	34 min
Sep 11, 10:02 AM CDT	Severe Thunderstorm Warning	LIX	Orleans, Saint Tammany	43 min
Sep 11, 10:50 AM CDT	Flash Flood Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard, Saint Tammany	2 hr
Sep 11, 12:07 PM CDT	Tornado Warning	LIX	Plaquemines	33 min
Sep 11, 12:51 PM CDT	Flash Flood Warning	LIX	Jefferson, Orleans, Plaquemines, Saint Bernard	3 hr
Sep 11, 12:51 PM CDT	Flash Flood Warning	LIX	Saint Tammany	3 hr
Sep 11, 2:14 PM CDT	Tornado Warning	LIX	Orleans, Saint Bernard	36 min
Sep 11, 2:14 PM CDT	Tornado Warning	LIX	Orleans, Saint Bernard	41 min
Sep 11, 5:34 PM CDT	Flash Flood Warning	LIX	Jefferson, Orleans	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.