SOUTHWEST LOUISIANA TORNADO OUTBREAK
IN ASSOCIATION WITH TROPICAL STORM FRANCES

(STORM ASSESSMENT)

Robert B. Darby*

National Weather Service
Lake Charles, Louisiana**

INTRODUCTION

On September 11, 1998, four tornadoes occurred in Southwest Louisiana, in association with Tropical Storm Frances, which made landfall earlier that morning along the Central Texas coast, south of Matagorda Bay. Atmospheric conditions remained favorable for tornadic development well after the tropical storm had moved inland. The tornadic cells formed in the heavy rain bands that moved onshore from the Gulf of Mexico. Below is a map of Southwest Louisiana showing the tornado locations in Jeff Davis, Acadia, Evangeline and Allen Parishes. The Acadia and Evangeline Parish tornadoes were classified as F1 on the Fujita scale, while the Jeff Davis and Allen tornadoes were classified as F0.

PRODUCTS ISSUED BY THE NATIONAL WEATHER SERVICE IN LAKE CHARLES

The following are the tornado warnings and severe weather statements issued during this tornadic event:

1053 AM CDT - Tornado warning - Jefferson Davis Parish
1133 AM CDT - Severe weather statement - Jefferson Davis Parish
511 PM CDT - Tornado warning - Acadia Parish
535 PM CDT - Severe weather statement - Acadia Parish
542 PM CDT - Tornado warning - Eastern Jefferson Davis Parish
545 PM CDT - Tornado warning - Allen and Evangeline Parishes
604 PM CDT - Severe weather statement - Allen / Evangeline / Jefferson Davis and Acadia Parishes
622 PM CDT - Severe weather statement - Allen and Evangeline Parishes

Four out of the five tornado warnings issued by the National Weather Service verified with actual tornado touchdowns. All of the tornadoes were radar indicated by WSR-88D in Lake Charles. Lead times on the warnings ranged from 2 minutes to as high as 34 minutes. This gave residents time to seek shelter from the tornadic storms. Many Basile residents interviewed after the tornado, stated they knew the storm was coming well in advance. Fortunately, only a few minor injuries were reported.

RADAR IMAGES, DESCRIPTION AND DAMAGE:

Tornado - 4 West of Lake Arthur on Pom Roy Road - F0

WSR-88D Radar Images - Base Reflectivity and Storm Relative Velocity:

Base reflectivity taken near tornado touchdown

Associated storm relative velocity product

Tornado Damage:

The tornado 4 miles west of Lake Arthur was the first tornado, occurring around 1055 AM CDT. One small home near the lake was totally destroyed, down to the concrete slab (see damage pictures below). Debris from the home was strewn over a half mile to the northwest. Luckily, no one was home at the time, so there were no injuries. A large house next door had several windows blown out due to the high winds. Approximate damage from the tornado is expected to be around sixty thousand dollars.

Home totally destroyed (fog partially obscuring photo)

Part of the roof was lodged into the ground over half a mile away

*Author's current affiliation: National Weather Service, Tulsa OK

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