Tornado counts are considered preliminary until final publication in the database of the National Centers for Environmental Information.
[1] Activity also tends to spread northward and westward in April compared to the cooler winter months and the Midwest and Great Plains tend to see increased activity, although the relative maxima remains in the southern states.
The shift northward and westward continues into May, as the maxima moves into the Midwest and the Great Plains as the springtime jet stream patterns tend to occur farther north (while the South begins to see decreasing activity), while the potential for tornadic activity also increases in the Northeastern United States.
[2] Overall, April saw near average levels of activity in the United States with 160 tornadoes being confirmed.
However, more consistent scattered to widespread tornadic activity began in the second part of the month, which included a moderate-sized outbreak between April 19–20.