While the search for survivors of the nightmarish Joplin, Mo., tornado is still far from over, AccuWeather.com meteorologists are forecasting that another round of deadly storms is about to occur today.

As of Tuesday afternoon, the death toll had already raised to 118, ranking the event among the top 10 deadliest U.S. tornadoes of all time. So why has the weather been so active?

According to AccuWeather.com Senior Meteorologist Henry Margusity, one of the theories is the strong La Nina that occurred. La Nina is the colder-than-normal waters in the southern Pacific. That area of colder water has caused a shift in the jet stream that has resulted in a wild and extreme weather pattern across the United States since the winter; however, recent trends have shown the La Nina has weakened, but the residual effects on the jet stream are still causing extreme weather in the form of tornadoes. It will take another month or so for the weather pattern to finally shift to one that is not as extreme.

While it is unclear as to what has caused the extreme weather, one thing is sure, the severe weather season will go down in the record books for the United States, Margusity added.

Below is a list of facts about tornadoes, offering a quick reference of tornado records and stats. Keep checking back to AccuWeather.com for the latest watches and warnings.

Tornado Statistics

1. How many tornadoes hit the U.S. yearly?
Tornado reporting methods have changed a lot in the last several decades, so the officially recorded tornadoes are believed to be incomplete. Although the actual average is unknown, recent trends indicate the number is around 1,300. This year, the number of tornadoes is 1,151 reports which is on pace for a record season.

2. How many people are killed by tornadoes every year?
On average, about 60 people are killed by tornadoes every year, most from flying or falling debris.

3. What were the top 10 deadliest U.S. tornadoes in the past?
1) March 18, 1925, Tri-State (Mo./Ill./Ind.), 695 deaths

2) May 6, 1840, Natches, Miss., 317 deaths

3) May 27, 1896, St. Louis, Mo., 255 deaths

4) April 5, 1936, Tupelo, Miss., 216 deaths

5) April 6, 1936, Gainesville, Ga., 203 deaths

6) April 9, 1947, Woodward, Okla., 181 deaths

7) April 24, 1908, Amite, La.,/Purvis, Miss., 143 deaths

8) May 22, 2011, Joplin, Mo., 124 deaths (pending final totals)

9) June 12, 1899, New Richmond, Wis., 117 deaths

10) June 8, 1953, Flint, Mich., 115 deaths

4. What city has been hit by the most tornadoes?
Oklahoma City
. The exact count is not known, but the total is more than 100.

5. Which city/town holds the most tornado fatalities in a single city or town?
Murphysboro, Ill. - at least 234 people lost their lives during the March 1925 "Tri-state" tornado.

6. What was the deadliest U.S. tornado day?
The Dixie Alley tornado outbreak on April 27, 2011, set a record of 335 deaths.

7. What was the biggest outbreaks of tornadoes?
The Super Outbreak of April 3-4, 1974, spawned 148 confirmed tornadoes in 13 states and resulted in the second highest death toll (317) for a tornado outbreak in the United States.

The April 25-28, 2011, outbreak may exceed this number once the final number of tornadoes is counted. So far, there have been 492 tornado reports.

 8. What was the biggest known tornado?
The Hallam, Neb., tornado of May 22, 2004, had the peak width of nearly 2.5 miles, which is close to the maximum size for tornadoes.

9. What was the strongest tornado? What is the highest wind speed in a tornado?
Tornado wind speeds have only been recorded in weaker ones, since violent tornadoes could destroy weather instruments. The highest winds that have ever been found during a tornado were about 302 mph near Bridge Creek, Okla., on May 3, 1999.

10. What were the costliest tornadoes?
On June 8, 1966, the Topeka, Kan., tornado had a cost of about $1,680,136,978 in 2010 dollars.

From AccuWeather.com (find the original story here); reprinted with permission.