El Nino

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The El Nino weather pattern is bringing lots of rain and snow to Arizona this week. Arizona State University climatologist Randy Cerveny will fill us in.

Ted Simons: Coming up next on "Arizona Horizon," a EL Nino update as storms continue to pass through the state. And education advocates talk about what they expect to see from the legislature this session. Those stories next on "Arizona Horizon."

"Arizona Horizon" is made possible by contributions from the friends of Arizona PBS. Members of your PBS station. Thank you.

Ted Simons: Good evening and welcome to "Arizona Horizon." I'm Ted Simons. A state lawmaker plans to introduce a bill that allows Arizona to ignore president Obama's executive action on gun laws. The bill introduced by representative mark Finchem of Oro valley would bar Arizona state and local governments from using employees or finances to enforce or support a presidential action, a supreme court opinion, or a federal policy that, quote, is not in pursuance of the constitution and that has not been approved by Congress. The bill does not define who would have the authority to determine the constitutionality of laws, legal opinions, and orders.
Ted Simons: EL Nino, apparently, is here, the much anticipated weather pattern that promised an abundance of rain and snow in Arizona is pushing a succession of storms across the state this week. Here with an EL Nino update is ASU climatologist Randy Cerveny. Big El Nino, as far as we're concerned. Good to have you back here. We have been talking about this with you for a long time. And you were saying just watch a big one is brewing. A big one is here.

Randy Cerveny: A big one is here. Pattern has finally switched this last week, and this is probably the kind of situation that we're going to have off and on for the next three to four months. So, if you like this last few days, be prepared for a lot more coming.

Ted Simons: Let's define terms. What is El Nino.

Randy Cerveny: El Nino is not these storms. I have heard forecasters say El Nino is here as in the storms. Well, they are, but they're the result of El Nino. El Nino is going on in the middle of the Pacific ocean, warming of the Pacific ocean. When you warm the Pacific ocean, you change the circulation, change the storm track and jet stream. And that is causing storms that normally would come up and hit Oregon and Washington to come down here into Arizona and California.

Ted Simons: And we're seeing those effects. Is that part of the ocean warm right now or was it warm earlier and that is affecting things right now?

Randy Cerveny: Both. It has changed the pattern. It actually started all of the way last May. We were talking about that and had some of the storms in the monsoon as a result of El Nino warming. But it really has warmed up within the last couple of months to hit a peak about now. And so we are really going to see the effects coming for the next few months.

Ted Simons: Okay. When would the peak happen as far as the effects are concerned? In a few months? Sooner rather than later?

Randy Cerveny: What we are going to tend to have are these kind of storms. Not anything like a super hurricane type of storm, but we are going to get storm after storm after storm. And that is what has happened in the Pacific ocean, a train of storms, one coming in after another. That's likely to continue for the next few months.

Ted Simons: As far as the El Nino effects, we had it last year, late in arriving, but those effects got here. Is this a continuation of last year? Is it complete and separate from the El Nino from last year? How does that work?

Randy Cerveny: This is a continuation of what we had last year. It has been building. We expected it to build and hit a max last year, but it kind of held off, kind of just below the threshold of what we call El Nino. Finally by last May it started building up and now it hit its max within the last couple of weeks.

Ted Simons: Really this week, I think we have a graphic of how much rain we have. We have three storms moving through this week. This is -- that's a lot of rain.

Randy Cerveny: That is a lot of rain. Notice California is also getting those rains.

Ted Simons: Oh, yeah.

Randy Cerveny: This is just this week. Remember, this is going to be a pattern of storms. Not any individual storm. This kind of pattern is likely to happen next week and then we will have more situations within the next three to four weeks of this kind of strain -- train of storms.

Ted Simons: Are they forecasting something like this next week?

Randy Cerveny: We are going to dry out over the weekend. There is a good chance we will have storms by the middle of next week again.

Ted Simons: El Nino effects, is it like what we are seeing, a persistent moderate rain and snow as opposed to violent storms?

Randy Cerveny: Exactly. That's the kind of storms that we're going to get. And in terms of helping us out, they are the perfect kind of storms. When you get this slow, gentle rain, it's able to soak in the soil and really be drought busting. This is exactly what Arizona and California have been wishing for for the last four, five years.

Ted Simons: I notice the snow level, the level for, you know, from rain to snow, like 5,000, 6,000, sometimes maybe 4,000 when the weather -- that's not so bad. That is good snow pack.

Randy Cerveny: Very good. California already at over 100% of the normal snow cover. All of this will help. When we get the snow cover, that helps even more because it slowly gets into the reservoirs as opposed to being a big rush event. This is exactly what we needed to kill drought.

Ted Simons: That snow pack is fantastic as far as the high country is concerned and that means we might not, forecasting here, might not see such a bad fire season in the high country. However, in the lower deserts --

Randy Cerveny: All of this rain in the desert is going to create a massive amount of flowers. This will be a wonderful spring for flowers. Also going to be a horrible spring for allergy sufferers. We will have a lot of pollen. When that dries out in May and June, it becomes the perfect fuel for the potential for desert wildfires.

Ted Simons: El Nino winters, effect -- does it lead to a particular weather pattern for the spring? Can we look forward to something this summer because we're getting this now?

Randy Cerveny: Well, this is -- the linkage to the summer monsoon is pretty weak. The situation here is that this is such a strong warming of the Pacific. This is such a strong El Nino event that the effects aren't going to be easily gotten over. We usually have a El Nino event that might influence the January and February rainfall. This will go into March and probably April, causing above-normal rainfall here in Arizona.

Ted Simons: With that in mind, is it such a strong El Nino that it could drift over into next year or could we just have a monster La Nina next year? Too hard to tell right now.

Randy Cerveny: The forecast models are suggesting that by next summer, June, July, we will be knocking off the temperatures in the Pacific so that we probably won't have a repeat of this next winter. But this winter is going to probably be enough for most people that want to have a good sense of rain.

Ted Simons: And quickly, the impact on the rest of the country, the rest of the world, what are we seeing? Is it typical El Nino effects here?

Randy Cerveny: We're seeing different places are impacted differently. For example, we get a lot of rain during most EL Ninos. Australia is burning up. They are in drought and they are going to have some nasty wildfires over the next couple of months because their impact of El Nino's change in the wind patterns. Different parts of the world get impacted very differently. Argentina is having massive floods. Depends on where you are as to what kind of effect these changing weather patterns have.

Ted Simons: Before you go, I have been doing this for quite a while. I remember El Nino a topic -- but it seems within the last five years, maybe a little longer, this has really become a strong predictor of winter weather, hasn't it? I mean, this is coming through.

Randy Cerveny: Yeah, what's kind much interesting, we hear a lot of people saying well, you can't predict climate change. El Nino is a climate change that happens once every five to seven years. We have gotten really good at predicting it. We are starting to understand how our climate actually works.

Ted Simons: You have been telling us all along. Take a bow. You got it right there. Thanks for joining us.

Randy Cerveny: My pleasure.

Randy Cerveny:Arizona State University climatologist

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