[1] Activity spreads northward and westward in May, with the maxima moving 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] In June, tornadoes are commonly focused across the Midwest and the central and northern Great Plains, and occasionally the Northeast, all due to their proximity to the late spring/early summer jet stream which continues to retreat farther north.
[3] Although some moderate outbreaks occurred, May was significantly below average with 237 tornadoes.
June was even less active with only 123 tornadoes confirmed, which is about half the amount of the month has on average.
The two months broke the above-average trend that had been observed at the beginning of the year.