This storm was an oddball.
You might expect a volley of violent tornadoes in the Plains or the South, but not in Pennsylvania and surrounds. This event stands out for the country as a whole, and was truly exceptional for where it occurred.
Now matter how you slice it, the first full week of May 2015 was a big one for tornadoes.
This outbreak had some issues, but it still ended up performing quite strongly. Several dozen tornadoes dropped across the southern and central Plains on May 9 with more further to the east on May 10.
The first significant tornado outbreak of 2015 brought tornado activity to a region spanning from Nebraska to Texas.
Like tornado season, the odds of the biggest tornado day of the year historically peak in May. Those days offer some other clues as well.
On April 11, 1965, and over a time span of approximately 12 hours, one of the most infamous tornado events in United States history took place.