TENNESSEE VALLEY – April 2011 stands as the most active month on record for tornado activity in Alabama.
Most recall the devastating, state-wide April 27, 2011 severe weather event, but if often overshadows the major tornado outbreak which occurred a few weeks prior on April 15.
The Tennessee Valley was not impacted in a big way compared to other parts of the state. Aside from a few damaging wind reports and a hail report, the severe weather was confined to areas south of Birmingham down to near the Gulf Coast.
The National Weather Service in Birmingham recounts the setup:
“A surface low, which had developed across the Central Plains on Thursday, the 14th, deepened as it moved into the Mid-Mississippi Valley. In response to this deepening, surface dew points in the middle to upper 60s surged northward into Central Alabama and deep vertical wind shear increased. By the morning of Friday the 15th, it was evident environmental conditions were going to be perfect for tornadic supercell development. The Storm Prediction Center issued the first Tornado Watch for Central Alabama prior to 8 am and supercell development began just after 11 a.m. across central Mississippi. These storms crept across the Mississippi and dropped multiple damaging tornadoes. The first tornado warning in central Alabama was issued at 11:52 a.m. in Marengo County and warnings were issued until 12:15 a.m. the next morning.”
The strongest tornadoes in Alabama were rated EF-3, with max winds as high as 150 miles per hour. Four tornadoes in Sumter, Tuscaloosa, Autauga and Marengo Counties were rated EF-3. Four deaths occurred as a result of these tornadoes– three in Autauga County near Boones Chapel, and one in Marengo County.
At the time, it was the deadliest tornado outbreak since the Super Tuesday outbreak in February 2008.
Several EF-3 tornadoes also occurred in Mississippi – a few of which stayed on the ground as they tracked into west Alabama.