Page 5 of WeatherReady

A Recap of the Spring and Summer Convective Weather Season across the Four State Region

Photo Courtesy of Robert Firth

The spring of 2006 across the Four State Region was relatively benign when it came to severe weather compared to some recent spring severe weather outbreaks this region has experienced. Typically as we transition into spring and we get the influx of Gulf of Mexico moisture into the region combined with warmer days, we get the development of strong to severe thunderstorms as storm systems move out of the plains into the Lower Mississippi Valley. The four-state region only experienced five of these widespread wind and hail events through the months of March, April and May. The spring convective weather season across the four state region is also well know for its tornado outbreaks but during the spring of 2006, only 3 tornadoes were reported across the region while tornado climatology says that during the spring months, an average of 15 tornadoes is more likely. This severe decline in the number of widespread, convective outbreaks across the four state region during the spring of 2006 can be directly related to an unusual northward shift of the jet stream stemming from high pressure aloft which remained anchored across much of the southern plains and a deep trough of low pressure which persisted across the Great Lakes into the New England states. This type of weather pattern resulted in a lack of deep moisture moving northward from the Gulf of Mexico into the four state region which in turn resulted in sparse thunderstorm development as storm systems moved into the region.

When the region experienced enough available moisture for storm systems to act upon, we did see a few widespread convective events during the spring of 2006. These events occurred on March 9th, April 7th as well as May 4th, May 10th and May 14th. These events were mostly characterized as widespread wind and hail events which affected northeast Texas, southeast Oklahoma, southwest Arkansas and northwest Louisiana. One of the more notable events resulted in a tornado which touched down near Lockesburg, Arkansas on March 9th. This tornado was rated an F0 in intensity (40-72 mph winds) resulting in a few large trees downed near the community. Another tornado, F1 in intensity, (73-112 mph winds) also touched down in Center Point, Arkansas on March 9th. This tornado was on the ground for nearly 11 miles resulting in numerous downed trees with a barn destroyed and minor roof damage to two homes. The third tornado of the spring touched down near Linville, Louisiana on April 7th and was rated an F0 in intensity. While this was rated a weak tornado, its damage consisted of roof damage to the local school in Linville and a large tree which fell on a mobile home. Fortunately there were no injuries reported with any of these tornadoes. Also worth mentioning was a thunderstorm which produced four inch diameter hail near the town of Sterlington, Louisiana on May 10th. This storm obviously did quite a bit of damage to area homes, businesses and vehicles. A squall line which moved across southeast Oklahoma on May 4th resulted in a measured wind gust of 91 mph near Idabel, Oklahoma. This wind gust ranked in the top 5 for one of the highest wind gusts ever recorded by the Oklahoma Mesonet wind recording sites in the entire state of Oklahoma.

The summer of 2006 across the four-state region was characterized by its abnormally dry conditions for the second consecutive summer. While June can be quite an active month when it comes to severe weather outbreaks, June was no different than the previous months of March, April and May when it came to its lack of widespread thunderstorm activity across the region. Instead, one heat related death was observed in June when a young man in Bossier Parish succumbed to the heat while working in his yard. The region did experience a widespread convective wind event on July 19th when much of northwest Louisiana and northeast Texas saw power outages from downed trees across power lines. What made this event unusual was that the convective storm system moved from east to west instead of the more traditional west to east movement we typically see from widespread convective storm systems. As we moved into the warmer months of August and September, severe weather typically ceases from being widespread and becomes more isolated in the form of damaging downbursts type events. Downbursts occur when a thunderstorm is unable to sustain its updraft therefore the downdraft becomes dominant and winds can reach 70 mph or greater but over a more isolated area. We saw these conditions on August 16th when several parishes in northwest Louisiana saw downed trees and power lines.

It's important to note that the four state region typically sees a second severe weather season beginning late in October and continuing through early December. While this season is typically not as pronounced as the spring severe weather season, the four state region can see its share of widespread convective wind and hail events as well as a few tornado events during this second severe weather season. The National Weather Service urges you to keep an eye to the sky and to remember your storm preparedness rules as we transition into this second severe weather season.