New Research Connects Tornadoes, Ocean Temperatures & ENSO
Weather forecasters are working on the ability to predict tornado outbreaks, including when and where they may occur, and providing more advanced warnings of severe weather that could produce tornado outbreaks. Current research may have found a link between El Nino–Southern Oscillation (ENSO) events and tornado outbreaks that helps improve these efforts.
Current Severe Weather Prediction Abilities
According to a report published in IOPScience's Environmental Research Letters, the current capacity to predict severe weather, including tornadoes, is approximately seven days. The report also suggests that by providing more advance notice, communities across the nation would be better prepared. Such advance warnings would also assist local, state, and federal agencies with preparedness and response efforts, helping protect communities and possibly reducing the economic impact of these severe weather systems.
Analysis for the report was conducted by a group of researchers from the University of Miami and the National Oceanic and Atmospheric Administration (NOAA) who focused on four variations of the ENSO events that may have an impact on tornado outbreaks across the United States.
ENSO and Regional Weather Systems
ENSO has two phases: El Niño, which causes an increase in warm sea surface temperatures of the middle to eastern region of the Pacific Ocean, and La Niña, which produces cooler sea surface temperatures in that same area. These shifting temperatures produce an increasingly amplified affect on the atmospheric processes across the U.S. that are conducive to tornado outbreaks.
Specifically, the researchers focused on springtime phases of ENSO and noted that it impacts the "North American low-level jets, which influence US tornado activity by controlling low-level vertical wind shear and moisture availability."
In particular, the research found correlations with persistent and strong La Niñas to the the 1974 and 2011 tornado Super Outbreaks.
2011 Tornado Outbreaks
The historic 2011 tornado outbreaks shattered records - a total of 199 tornadoes killed 316 people across 5 states, causing an estimated $21.7 billion in damages.
Five of the deadliest tornadoes included three EF-5 and two EF-4 tornadoes, and produced 208 of the 316 fatalities. Many of the tornadoes also damaged or destroyed weather radio towers or knocked out power to weather forecasting offices, interrupting transmission of future watches and warnings.
Caution Advised by Researchers
The report cautioned that the research is in its early stages and although a correlation has been found for springtime months, tornado outbreaks can occur anywhere and at anytime across the U.S., so residents should be prepared. This is especially true for communities at risk for severe weather on a routine basis - whose residents should always be prepared, and ready to heed watches and warnings.
Researchers are hoping that extended forecasting beyond seven days will allow additional time for preparedness, which might increase warning times, protect infrastructure, and save lives.