This year's tornado season is now tied for the fifth deadliest on record. That ranking could climb even higher by the year's end, one meteorologist said.

"It's possible that by the end of the year we'll be the second deadliest on record," said meteorologist Harold Brooks, of the National Severe Storms Laboratory, in a press briefing on June 15.

So far this tornado season, the death toll stands at 537, making it the deadliest year for tornadoes since 1936, according to preliminary data from the Storm Prediction Center. Tornadoes also killed 537 people in 1896. [Related: The Top 5 Deadliest Tornado Seasons.]

The top five ranking was passed when officials recently reported that the monstrous tornado that hit Joplin killed 151 people. That tornado was classified as an EF-5, the most intensely damaging on the Enhanced Fujita tornado damage scale. The Joplin tornado is the deadliest single twister to strike the United States since 1953, when a tornado killed 116 people in Flint, Mich., according to National Oceanic and Atmospheric Administration (NOAA).

The season has slowed down in June, which may be a sign that the second half of the season will be quieter. In years past, most of the tornado-related deaths happened by the middle of June, with very few deaths in the second half, Brooks said. Most of the post-June deaths occur in November, the so-called second tornado season.

Regardless of the final ranking, the death toll from the 2011 tornado season hasn't been seen in 75 years, and looks like a typical year prior to 1925, Brooks said, when tornado warnings were virtually non-existent. To compare this year's count to other recent years, in 2010, tornadoes killed 45 people in the United States, and in 2009, 21 people.