And is the custom in many of these air mass clashes, Louisiana and the Gulf South are the battleground. Since a lot of us didn't go to weather school, the National Weather Service defines a "Severe Thunderstorm" as a storm that produces quarter-sized hail or larger and wind gusts of 58 miles per hour or more. What Parts of Louisiana are at Risk For Flooding and Severe Storms? The extreme northern and northwestern sections of the state could experience severe weather as soon as this afternoon or evening. But the majority of the state will be at risk for strong to severe storms on Wednesday.