April was a busy month in Dixie Alley
By Skip Rigney
April often brings more tornadoes to the mid-South than any other month of the year, and April 2020 is living up to, and even exceeding, the historical averages.
Many people think of the “Tornado Alley” of the Great Plains of Texas, Oklahoma, and Kansas. However, in April tornado activity is often centered farther east and south in what meteorologists refer to as “Dixie Alley” comprising portions of Arkansas, Louisiana, Mississippi, Tennessee, Alabama, and Georgia.
During April strong low pressure systems often move eastward from Texas and Oklahoma into the mid-South. The wind circulation associated with these lows can cover areas 500 miles across. Within these large circulations there are sharp boundaries in temperature, humidity, and wind patterns. The clashes between different air masses can be especially violent during the spring as warm air from the south and near the surface makes a comeback, while the air aloft is quite cold.
This month three low pressure systems, the most recent on Wednesday, have tracked across Dixie Alley spawning over one hundred tornadoes in the region according to statistics compiled by the National Weather Service’s (NWS) Storm Prediction Center. The average number of April tornadoes in Dixie Alley is about 40.
The average number of April tornadoes in Mississippi is nine, but there is a wide range from year to year. In April 2011 there were over 100 tornadoes in the state, while none were reported in April 2015. This April, working off initial reports, which are plotted on the map shown here, nineteen tornadoes in Mississippi have been confirmed by NWS field survey teams. Two tornadoes crossed the same area in northeast Jones County. Four had winds of 150 miles per hour or greater.
Although Pearl River County is just south of Dixie Alley, we got in on the action last Sunday evening. A survey team from the NWS in Slidell found that a tornado touched down along I-59 just north of the McNeill exit. The storm moved southeast for three miles, snapping trees and causing minor structural damage. After crossing McNeill-Steephollow Road, the tornado either lifted off the ground or dissipated near Bouie Road. The team estimated maximum winds were 105 mph and that the tornado was about 200 yards at its widest.
Fortunately, chances of any more severe weather in south Mississippi appear slim as we close out the month of April. In general it looks to be a mostly sunny, warm spring week. An approaching front on Tuesday night or Wednesday may kick off a few showers, but the associated low pressure system and its energy is predicted to stay far to the north.