October 18, 2013
Pacific Ocean Temperatures Could Predict Where Tornadoes May Strike
[WATCH VIDEO: Predicting Tornadoes]
Brett Smith for redOrbit.com - Your Universe Online
When and where a tornado will strike is extremely hard to predict, but weather researchers from the University of Missouri-Columbia have found temperatures in the Pacific Ocean could be used to predict where tornado-causing storms might strike.
According to the research team of Laurel McCoy, a graduate student researcher, and Tony Lupo, a meteorology professor and chair of atmospheric science in MU’s College of Agriculture, Food and Natural Resources, when surface temperatures in the Pacific were warmer than average, the US saw over 20 percent more tornadoes that were rated EF-2 to EF-5 on the Enhanced Fujita scale, which rates the power of tornadoes based on the damage they cause.
The team also saw that when surface temperatures were above average, tornadoes usually touched down to the west and north of tornado alley, a north-south area of the Midwest from northern Texas to Nebraska that is known for having more tornadoes than any other area in the US. The team said lower surface temperatures tended to send tornadoes away from southern states like Alabama, and into Tennessee, Illinois and Indiana.
"Differences in sea temperatures influence the route of the jet stream as it passes over the Pacific and, eventually, to the United States," McCoy explained. "Tornado-producing storms usually are triggered by, and will follow, the jet stream. This helps explain why we found a rise in the number of tornados and a change in their location when sea temperatures fluctuated."
For their study, which was presented at the National Weather Association Conference this week, the team looked at over 56,000 tornado-like events from 1950 to 2011. They found clear evidence linking tornado activity and a climate trend called the Pacific Decadal Oscillation (PDO). PDO periods, which were uncovered in the mid-1990s, are long-standing temperature developments that can last nearly 30 years.
According to NASA scientists, the PDO has just entered into a "cool" phase.
"PDO cool phases are characterized by a cool wedge of lower than normal sea-surface ocean temperatures in the eastern Pacific and a warm horseshoe pattern of higher than normal sea-surface temperatures extending into the north, west and southern Pacific," McCoy said. "In the warm phase, which lasted from 1977 to 1999, the west Pacific Ocean became cool and the wedge in the east was warm."
The researchers suggested their findings could be used to improve public safety during storm seasons. In 2011, over 550 people died and more than $28 billion was lost in property damage as a result of tornadoes, according to the National Oceanic and Atmospheric Administration.
McCoy said her findings could help public officials to save lives in the future.
"Now that we know the effects of PDO cool and warm phases, weather forecasters have another tool to predict dangerous storms and inform the public of impending weather conditions," McCoy said.
In another recent study presented in June at 12th Americas Conference on Wind Engineering, University of Arkansas researchers used 3-D computer models to show how the lower levels of a tornado's vortex are significantly disrupted if it passes over a hill with a height equal to or greater than the radius of the vortex. The researchers said their findings could be used to identify safe areas for construction.