ST. JOHN: You're listening to Midday Edition on KPBS. I'm Alison St. John in for Maureen Cavanaugh. What's up with the weather? This has been quite an interesting winter. We have had very little rain. It's been more like summer. What does that mean for the year ahead, and what does it bode for the fire season? We have Alex Tardy, who is warning coordination meteorologist for NOA, the national weather service here in San Diego. TARDY: Thanks for having me. ST. JOHN: We hear a lot of people saying that the weather in San Diego this winter is pretty weird. It's been warm and sunny. Mostly it's been dry. Are we right? Is this unusual? TARDY: It's a little bit unusual. Most people that live or visit San Diego don't expect a lot of weather, and usually don't see a lot of weather when they come to the city. And the main reason why they're living here is for the lack of weather. But across the whole country, you can kind of say the same thing. The weather has been extreme with tornadoes in the mid-west last spring, carrying all the way through. We actually had an early wet season. We were 300% our normal in November for San Diego. So we started off really wet, went very dry. The bigger issue is the state in general has been dry, and that could have implications on the water fly and the fire potential. ST. JOHN: What would you say is the cause of all this? TARDY: We like to pin it to one phenomenon across the globe, but we can't blame this all on La Niña. We are in a moderate La Niña, which means cooler than normal sea surface temperatures in the Pacific ocean. But really, there's multiple connections going on across the globe. We call it the north Atlantic oscillation, which is cold air in the north atlantic and Canada, which has been altering the jet stream across the United States. There's a reason why Alaska got three of foot, and England got tremendous rainstorms earlier this year. The jet stream was pushed way farther north than it usually is. That's not the blame of La Niña. There's other things going on globally in our temperatures. We expect this type of extreme weather to be more common, if you will, in the next several years because of climate change and variability. ST. JOHN: Why? TARDY: Well, climate change or variability, we expect things to be dryer, longer dryer periods, hotter stretches, more heat waves. Then at the same time, other parts of the country will be having wetter than normal times, maybe even snowier than normal. This year has been on the other end, where most of the state, if not most of the country has really seen a lack of snow overall. Skiing has really suffered across the west in general up until the storm we had this past week, which really saved us with three to 5 feet of new snow. But before that, we were mostly dry. The gesturing was well north. British Columbia, Alaska, and across England and the northern Atlantic ocean. ST. JOHN: We're speaking with Alex tardy, who is the warning coordination meteorologist here in San Diego. And if you have a question for him, we're always wondering how it's going to affect us next, you can call us at 1-888-895-5727. So what is the difference between La Niña and El Niño? TARDY: Yeah, the thing for California is precipitation tends to be associated with one or the other. La Niña is a cooler than normal sea surface temperatures in the Pacific ocean, and we're not talking much. We're talking one to two degrees Celsius cooler. But over a large area of the equatorial Pacific, but that alters the jet stream. It has enough influence to either suppress precipitation or increase precipitation on either end. And that alters the jet stream and tends it shift it a little further north. Now, El Niño is the one we commonly associate with wet, right? We usually say El Niño, good! A lot of precipitation, maybe too much. Of that's above normal temperatures in the ocean. And we're only talking a couple degrees, but that can have a significant impact in enhancing the jet stream, pulling it further south. Last year, we were in a La Niña, and it was one of the wettest Decembers ever. And October, November, December was 2010 was very wet. Then we dried out, and things shut off for a while. We kind of saw that this year too. Not nearly as wet. We're not able to associate La Niña or El Niño with a one-on-one correlation. It's not working out. ST. JOHN: How do you mean by that? TARDY: We're not able to say when you have an El Niño you have a significantly above normal precipitation. Now, there has been years where that's worked out really good. But the scientists are finding out that these other connections like the north Atlantic oscillation, the arctic oscillation, basically the polar jet stream and how that interacts with the subtropical jet stream, we're still learning about how these interact because what happens downstream or upstream, the atmosphere is like a big river. When you send something down stream, it has an impact either way. ST. JOHN: How long have been looking at El Niño and La Niña? TARDY: We really started looking at it hard in the 90s. NOA spent a lot of money on putting buoys deep in the water to see how much the reservoir of water cooler than normal or above normal temperatures were. And it started way before that. Fishermen in South America noticed that the fish population and type changed, a little bit cooler water, they had different species. A little bit warmer water, it wasn't good. So that goes back 100 years. But scientifically, we've been looking at it really closely 20, 25 years. But we're -- it's a little bit frustrating because not every La Niña and El Niño is the same. They have brothers and sisters that are quite different. ST. JOHN: That's quite a long period of time to be watching it. When you look at what's happening in the last few years, and this is your job to keep an eye on this all the time, is there a significant shift in one direction or the other? TARDY: We're seeing a period where we have normal La Niñas back to back. This year is back to back, and around 200 zero there was more in a row. And wee seeing more change, flip flop from El Niño to La Niña, back and forth. Usually there's a period where it's neutral or not much change. So we are seeing variability. And that may be why we're seeing such variable weather as well across the country. ST. JOHN: Okay. So, now, is it possible for you to predict what the coming year is going to be like from what's happened so far? TARDY: We're not very good at that. We look at it statistically. And you could say -- I've had people telling me this November was really wet, so that means the winter is going to be wet. Well, are it doesn't quite work out that well. It's not that easy. We can predict very good seven to ten days using numerical weather prediction or computer models. Not so good when we're talking about a month to two months. Of that's mostly statistical. So we look -- we correlate it and see if there's any relationship between the state of the sea surface temperatures or the atmosphere as a whole, and what that's resulted in the past in terms of precipitation, temperature, things like that. ST. JOHN: So what is the prognosis for our water supply bearing in mind what's happening this winter? It doesn't seem like we've seen a lot of rain. TARDY: That's a good question. Most of the Sierra Nevada, where we get a lot of our water from, and the Colorado river where we get a lot of our water from, and may take for granted, they're 30 to 50% of normal. And that means well, be we're halfway through the winter. These are the west months. So if we're going to get storm, this is the time of year we need them, because these are the ones that will have a big impact like the one last week. So it's looking in a nutshell, try conditions in the spring, a higher concern for fire weather, especially when we get off-shore events, Santa Ana-type winds, and our water supply is doing really well because of last year, a record-breaking winter season, despite it being a La Niña. ST. JOHN: So it broke all the patterns. TARDY: Yes. It was the wettest in this area since 1933, including Southern California. And the wettest December ever. So all that water we captured, we actually had too much water last year. Now the reservoirs are doing very well. But the problem is, when you have a dryer than normal season like it's looking like this year for most of the state, it catches up to you. You start draining resources. The impact probably won't be felt until later this summer or this fall because we aren't able to fill the reservoirs all the way back up and top them off like last year. ST. JOHN: So our system is basically relying on a certain amount of rain every year. So it's not going to see us through to the end of this year. TARDY: That's true. Our water system tends to respond 6-12 months. When you're talking aquifers and groundwater, it takes longer, might be 2, thee, four years. When we're talking short term storage in our small reservoirs, those can be an impact that you visibly see in a matter of 6-12 months. So after a drier like this year, I'm not going to say we're going into a drought, but it can lead to drought-type situations if you don't replenish that water. ST. JOHN: Okay. Now, the rain that we've just had, you know, sometimes in San Diego the deserts burst into bloom, and Torrey Pines is a delight to walk through. Is it going to be one of those years? TARDY: We have had just enough rain, November, a little bit in December, then we dried out for four weeks around Christmas and into January. Just enough rain that things have greened up, flowers are starting to bloom. So the normal January, February, early spring that we have here in Southern California shouldn't be impacted much. It should be just as beautiful as it normally is. Maybe not quite as good as it was last year because it was so welt for the first half of the winter, so widespread, but we're already starting to see it now with flowers. And we've been lucky. Southern California is the only place where there's been above normal precipitation up until December. ST. JOHN: Really. So we have had more than the rest of the -- TARDY: Yeah, the jet stream has been so erratic that it's been split. Everything's been coming down to Southern California or going north into Washington. ST. JOHN: So we should be grateful. TARDY: We should be grateful that we've gotten quite a bit of precipitation compared to the rest of the region. ST. JOHN: Great. Well, thank you very much for coming in. TARDY: Thank you for having me.
San Diegans are getting used to wondering what happened to summer. For the past couple of years, June gloom had edged into July and even August. Beach-goers shivered well into the summer months, and tourists probably felt ripped-off. This winter is unusual, too. The weather has been unseasonably warm at times, with high-pressure keeping the days warm, the nights cold and the air dry.
There is an explanation for weather phenomena, of course, and this year it's called La Nina. We are in the midst, in fact, of back-to-back La Nina conditions.
