Trouble Ahead (image) The Earth Institute at Columbia University Share Print E-Mail Caption A tornado brews near El Reno, Okla., May 2013. A new study links the frequency of tornadoes and hailstorms in parts of the southern United States to ENSO, a cyclic temperature pattern in the Pacific Ocean. Credit John Allen Usage Restrictions Credit must be given Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.