NOAA’s Storm Prediction Center reports 716 tornadoes in the US in the first 5 months of 2015. Although most tornadoes occur in the American Midwest and South, vortex storms are not a US exclusive. They occur in many other countries and can be as destructive as in the US, if not more so.
A good example is the tornado that sank the Chinese cruise ship Eastern Star in the Yangtze River on June 1, 2015. According to the China Meteorological Centre, a supercell associated with a stalled storm front spawned an EF1 tornado with funnel wind speeds up to 109 mph (175km/h) in Hebei Province near the Yangtze. While crossing the river, the tornado struck the cruise ship, causing it to capsize. 434 people were confirmed dead in the tragedy.
In Brazil, on April 20, 2015, an EF2 tornado with wind speeds up to 135 mph (225km/h) struck the city of Xanxere, damaging 500 homes. 1 person died, 120 were injured, and 1,000 were left homeless. On May 5, 2015, an EF3 tornado with wind speeds to 165 mph (275kp/h), hit the German city of Bützow causing major structural damage to the city’s buildings. On the same date in Hamburg, straight-line thunderstorm winds killed 1 person and injured 30.
Worldwide tornado fatalities so far in 2015 total 463: including 434 in China, 14 in Mexico, 10 in the US, 3 in Myanmar, and 2 in Brazil.
In the US, on March 25, a waterspout developed over Keystone Lake near Sand Springs, Oklahoma. The spout became an EF2 tornado that moved through a mobile home park, resulting in 1 fatality, 30 injuries, and extensive property damage.
On April 8, an EF4 with wind speeds reaching 200 mph (330km/h) hit northern Illinois, killing 2 people and injuring 22. On May 9, a series of EF3 tornadoes killed 1 person near Cisco, Texas, 2 people in the town of Van, Texas, and another 2 in Nashville, Arkansas, making a total of 5 deaths on a single day.
Although tragic for those impacted by the storms, the 2015 tornado fatalities and property damage totals are somewhat less than those in prior years. For example, in 2011, 553 people died in a series of violent tornadoes. Alabama and Missouri were especially hard hit during that year. The average annual number of tornado deaths in the US is 109.
The reason given by NOAA for the lower than normal tornado activity in 2015 is the pattern of a long-term trough in the east that brought cooler temperatures to that part of the country, and a high-pressure ridge that has persisted in the west bringing warmer temperatures. The combination has reduced the number of thunderstorms and supercells over the middle part of the US. That pattern will change and there will be future years with above average tornado activity, and they may be stronger than ever due to global warming. If you live in a tornado prone area, be prepared.