May 13, 1998 transcript #: 233-3
Subject(s): El Nino, tornadoes
Title: EL NINO & TORNADOES
By now you've heard enough trashy El Nino melodrama to fill a week's worth of made-for-TV movies. But El Nino is not always the villain its made out to be. Hi Im Dave Thurlow for the Weather Notebook. Heres some of El Ninos good side.
The Atlantic Ocean tends to produce fewer hurricanes during El Nino years. It also seems that summer tornado outbreaks in the countrys mid section don't like El Nino either. Instead, they prefer La Nina, El Ninos alter ego. La Nina is the cooling of the same Pacific waters that are warmed during El Nino. It more or less alternates with El Nino over several years though there are fewer La Ninas than El Ninos. So why do summer hurricanes and tornadoes like to avoid El Nino? Because of El Ninos strong subtropical jet stream. This river of air helps keep the South stormy during an El Nino winter, as it did tragically this winter and early Spring. If El Nino lingers into summer, the strong jet tends to keep the juiciest tropical air locked across the Gulf of Mexico, away from Tornado Alley and points east, where it might clash with colder air masses to produce twisters. This same El Nino produced jet stream tends to blow Atlantic hurricanes apart before they really get going.
So as of now, El Nino is just barely hanging on, so this summer should be about normal for tornadoes and hurricanes nationwide. But please remember these are not specific forecasts. The atmosphere, on any given day, can cook up about anything it wants regardless of who is on the marquee in the Pacific Ocean. Todays show was written by Bob Henson and produced by Bryan Sejvar. Generous support for the Weather Notebook is provided by Subaru, the beauty of all wheel drive and by The National Science Foundation.