NOAA's National Centers for Environmental Information
April is usually the beginning of the active tornado season for the central areas of the United States. Storm systems moving across the country interact with the warm temperatures and a moist atmosphere that accompany the arrival of spring. The number of tornadoes during the January–March period during 2010 was much below average, getting the year off to a slow start. The first three weeks of April were also extremely slow with only 19 tornado reports between the 1st and 21st of the month. The last nine days of April were extremely active with several tornado outbreaks associated with 176 preliminary tornado reports, bringing the number of tornado reports during the month to 195. This ranks April 2010 as the eighth busiest April since reliable records began in 1950, if all preliminary reports are confirmed. Including 2010, four of the ten top April tornado counts have occurred since 2000 (2006(second), 2009(third), 2008(ninth). The location of tornado occurrence was similar to the past few months, with the typically active 'tornado-alley' receiving fewer tornados than the Southeast and Gulf Coast regions.
The tornado outbreaks which occurred between April 22nd and April 24th were associated with a slow–moving extra tropical cyclone. The storm system moved eastward from the Rocky Mountains bringing strong winds, damaging hail and killer tornadoes from Colorado to North Carolina. One hundred thirty six tornadoes were reported over the course of three days. The most active day was April 24th, with 77 preliminary tornado reports, mainly in the Southeast. The deadliest tornado of 2010, and first EF–4 of the year, occurred on this day, when a tornado touched down in eastern Louisiana and tracked eastward into Mississippi with a 149-mile (240 km) track and a maximum width of 1.75 miles (2.8 km). This track length is one of the longest tornado track on record. Yazoo and Holmes counties were particular hard hit when the tornado reached its maximum strength with estimated winds of 170 mph (274 km/hr). Across the two states at least 10 people were killed and 146 injured. One unusual characteristic of this tornado was the time of day it formed and dissipated—11:06 am and 1:52 pm, respectively. Most long lasting and damaging tornadoes occur between early evening and nighttime.
The second significant outbreak for the month occurred on the 30th and extended into the first few days of May. On the 30th, 29 tornadoes were reported along the Mississippi Valley from Arkansas to Wisconsin. The tornadoes occurred within thunderstorms that were associated with a frontal system moving across the middle of the country. One death was reported in Scotland, Arkansas when an EF–3 tornado destroyed a house. At least two dozen others were injured across Arkansas (Source: NWS). Excessive rainfall was also associated with the event which brought flooding to central and northern parts of the state.