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July 20th, 2009
12:43 PM ET

El Niño making a comeback – what it means

No matter where you live in the country, chances are you've seen some strange weather this summer. The experts say that it might have something to do with the weather phenomenon known as El Niño. It's making a comeback.

Gene Norman worked on weather monitoring technology for NASA and is now the chief meteorologist at KHOU-TV in Houston. Norman spoke to John Roberts on CNN’s “American Morning” Monday.

John Roberts: We know how much you love El Niño. Explain what happens here in an El Niño year.

Gene Norman: The way to think about El Niño is it's kind of like a pendulum out in the Pacific Ocean. The water temperatures fluctuate between being warmer than normal and being cooler than normal. Now we are back into an El Niño phase. We’re monitoring abnormally warm water out there and what that tends to do is shift the pattern of jet streams. It intensifies the subtropical jet streams so it brings that tropical air from the Pacific out across the southern United States. That should lead to a wetter winter and stormier spring for us here in the South. And with Texas being in a drought for the last two years, that's great news. Across the Northern Plains and over to the Great Lakes and the Northeast, we're looking for a somewhat warmer winter with perhaps less snowfall than you all have been experiencing.

The other thing that El Niño does by shifting the jet streams, it brings them over the Caribbean and the tropical Atlantic, introducing more shear into the atmosphere, and that helps reduce the overall number of tropical storms. Now it doesn't mean we're not going to have any tropical systems this particular summer, but what it does mean is we'll probably see fewer of them. Back in 1983, we had an El Niño season and, of course, we had Alicia. We’ll never forget that here in the Houston area. That was a summer we only had four total named storms. 1992 was another El Niño season and, of course, we had Andrew, a very powerful hurricane in south Florida. But in that year, there were only seven named storms. So the overall number of storms could be less, but there might be one big one that gets you. So you can't rest on the fact that El Niño's going on. But it could be good news.

Roberts: I remember back in 1992, when Andrew was, and that upper level wind shear was keeping it disorganized. Then it jumped north of that subtropical jet and wound up into a monster category 5. But we all remember the El Niño year of '97 and '98 where there was so much devastation to the California coastline. When we talk about an El Niño brewing this year, how strong might it be? And also in terms of less precipitation, warmer temperatures in the northern tier of the country – in Vancouver this winter, we've got some Olympics. Are they going to get any snow there? Talk to us about California and talk to us about snow in British Columbia.

Norman: Well, that's going to be a little bit dicey for snow in British Columbia. It'll all depend on when we start to see the drop of the surge of the polar jet stream. That brings the cold air out of Canada. As far as Southern California and as far as the South, again, we could see more stormy weather. It all depends on how deep the El Niño gets. They have about 70 buoys that are out in the Pacific constantly monitoring the water temperatures out there, and that tells us what's going on as far as how deep that warm water is going. And we're still getting a sense of what that’s looking like. I don't know that it's going to rival the '97, '98 El Niño, but it might come close.

Roberts: In terms of hurricanes, is there enough of an El Niño now that to keep the hurricanes a little more disorganized than they might normally be in a typical year?

Norman: Well so far we are seeing more shear out in the Atlantic. At the same time last year we already had three named storms. So the fact we're seeing more shear – some of those tropical waves coming off the west coast of Africa have not had a chance to intensify. So that’s good news early on in the season. But of course, things will start to heat up by the time we get to August and early September.


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