El Niño and what it means for San Diego weather

S1: Welcome in San Diego , it's Jade Hindman on today's show , the typical San Diego weather may not be so typical in the seasons ahead. Thanks to El Nino , we'll talk about how the weather may feel different. This is KPBS Midday Edition. Connecting our communities through conversation. The weather pattern we see every few years that makes San Diego feel more like Florida at times is here. Yes , it is called El Nino , and this year's system could be among the biggest on record here. To tell us more about what that means for us in San Diego and across the country is Alex Tardy. He's a former meteorologist with the National Weather Service , founder of Weather Echo , and our weather expert here on Midday Edition. Alex , welcome back to the show. Hi.

S2: Hi. Thanks for having me on.

S1: So glad to have you here. So El Nino changes so much in our atmosphere. The water is warmer at the beach. The rainstorms are more frequent. Um , when was the last El Nino we had? What happened then? Yeah.

S2: Yeah. So El Nino comes around every 3 or 4 years. The last one we had was 20 , 23 , 24 , but the last big one was 2015 , 2016. Uh , so that El Nino end up being very strong and the one that we're expecting to see develop , which is ongoing and just forming , is supposed to be nearly as strong as that. Wow.

S1: Wow. When it was so strong in 2015 , what did we experience like? Was there were there floods? Were there extremely hot temperatures? What was the what was that like?

S2: Well , that's the thing with El Nino. So it's not quite a weather pattern. It's a ocean anomaly. And what we mean by that , it's a condition along the equator , where we measure the water temperature and we measure it by cooler than normal or warmer than normal , which is El Nino. So why that's important is in the tropics that can change our jet stream. It can add energy. It can warm the water in a large part of the Pacific , not just the equator. So in 2015 , 2016 , that winter was actually an anomaly itself , meaning it did not pan out to be what we expected. Most of the storms went to the north even though the jet stream got excited active. Most of the storms went up into Seattle in Southern California that year in a very strong El Nino was actually below normal in rainfall.

S1: So what do El Nino conditions potentially mean for our summer here in San Diego?

S2: So in the short term , whenever you add warmer water and when you spread it out along our coast of Southern California , what you're doing is you're making it more muggy , more humid. You're adding moisture to the air. And you're also affecting our air conditioner , which is the Pacific Ocean , so that natural cooling is not as efficient. So you can end up with a little muggy or more sticky , humid type of summer and warmer conditions. Overall. When you see that warming going on at the Pacific for the short term now it also can affect the tropics in terms of hurricanes. It can make more of them in the Pacific , which seems intuitive , right? Warmer water , more energy , more hurricanes. But in the Atlantic it does the opposite. Because what's happening is not only are you warming the water , but you're exiting the jet stream or wind flow , which can interfere or prevent hurricanes in the Atlantic from forming. So that's the power of El Nino. It does different things across the globe. Wow.

S1: Wow. So , you know , with without that air conditioning , then how hot are you expecting temperatures to get this summer?

S2: Well , we are expecting conditions to be warmer than an average summer and just a few degrees of water that's warming in the equator , and equating that all the way up to along the Southern California coast , that can affect our temperatures , sometimes by ten degrees. In most cases , it's more subtle. 3 to 5°F is where we see warmer temperatures. When we see that warming of the water. Now , the key with all of this is how the atmosphere responds. So the ocean and the atmosphere. And this is really important with El Nino , with education and understanding of the science. And we're always reminding even scientists this that El Nino is an ocean condition. And that doesn't guarantee or necessarily mean it's going to talk and communicate with the atmosphere in a 1 to 1 fashion. So the atmosphere can still do different things. Even though we see a developing El Nino.

S1: You know , we're talking about the ocean warming up , but there's a huge impact When that happens , even if it is just a few degrees. Tell me a bit about what happens to the ecosystem in the ocean when this happens.

S2: Yeah , so it can affect fish. And that's actually how , um , El Nino was discovered years ago , half a century or more ago , fishermen noticed different types of fish in different areas along the South America coast. Uh , they didn't know why , but it was only occurring every few years. Every 3 to 4 years , sometimes every five years. So with that massive warming along the equator , and when that expands and spreads up along Central America and the Southern California coast and the Baja , uh , different species can be attracted to that , and other species can be , uh , against that where they go and try to avoid it. So it really can change the ecosystem of our fish along the coast and other type of species that live in that water. And that's a lot. So like in 20 1516 we were seeing some small crabs and other type of organisms along the coast that we don't normally see all the way up into Southern California because of that warming. Wow.

S1: Wow. And it's interesting because as we speak now , I see that there are flash flood alerts all along the Gulf Coast in Florida , Georgia , Mississippi , Louisiana and Texas. Um , just to to emphasize how this weather pattern impacts the country. Like , you know , many are referring to this year as a super El Nino , too. So what is particularly remarkable about that forecasters , about what forecasters rather are seeing this year? Yeah.

S2: Yeah. Believe it or not , with El Nino , the the occurrence of the water and the warming and cooling of the water , that is actually relatively easy to predict. Um , it's a large area. It's slow moving , it's slow developing. It evolves over time , months. So in this scenario coming up , we are predicting very strong , uh , NOAA , National Oceanic and Atmospheric Administration. They just updated their rankings and they call it relative um , relative ocean Nino index. It's a mouthful. So the r o and I is a measure of that El Nino , and we've only seen about five of them that have been very strong. And the one we're predicting coming up is also very strong. So you go back to 82 , 83 , 97 , 98 , for example , and of course 2015 , 2016 , all of those were very strong. So they were over two degrees Celsius , which again doesn't sound like much , but an ocean. The heat capacity of water is huge. Uh , so that kind of change is massive. So we are expecting similar over 2.0 Celsius. And that puts it in the very strong category. And the confidence is really high because again , predicting the ocean condition along the equator is relatively easy. It's predicting the effects of that or the impacts of that such as the storms , the rain , the snow and everything that comes afterwards.

S1: We talked about what this means for our summer , but what does this year's El Nino mean for fall and winter as well?

S2: So we've seen a lot of times with El Nino that you don't necessarily have an early onset of rain , and that's really important for fire weather conditions. Um , and you don't also miss out on Santa Ana , which is very important for fire weather season. So you can still get big Santa Ana wind events in the fall , and you can still have very warm , dry periods in the fall. And this affects our fire weather season. So we also have seen that you can get more thunderstorms over our mountains and the deserts during the summer and early fall , which is good for the Colorado River area , which is really stressed. They need all the rain they can get. Um , but you still have to deal with the normal dry periods of the summer. You still have to deal with the wind or the Santa Ana in the fall. And what we've seen a lot with these big El Ninos is when it develops , when it sets in there , um , it really can be active for a prolonged period. For example , January and February , uh , are really seem to be loaded a lot of times in some of these big , very strong El Nino years.

S1: What's the connection between climate change and this year's El Nino?

S2: Well , that's one thing that a lot of scientists , including in our backyard in Scripps at UC San Diego , are looking at because in general , we all kind of agree that even when you have an El Nino , that you're not seeing the same response in the atmosphere and the circulations and the storms that go around the globe. So in other words , what we once thought 20 , 30 , 40 years ago with El Nino , it's not translating the same. And we think that's partly or even significantly , largely due to the fact that we have overall warming in the Atlantic and , of course , the Pacific , and that warming of the ocean and the land as well. But the warming of the ocean is influencing some of the effects that El Nino used to produce and how it interacts with the jet stream or the atmosphere. So we're not seeing that same correlation , and it makes it even more challenging to predict the actual storms or weather patterns down the road. Even when you see El Nino forming , as we do right now from space , or when you measure it with a buoy.

S1: You mentioned wildfires. Have we , you know , seen and we've seen a number actually in our area over the last couple of weeks. They've been quickly put out , I should add. But what are our current conditions? What are our current wildfire conditions like here? And how might El Nino impact that?

S2: Yeah , with fire weather , especially in Southern California. But really we're seeing this in Northern California , too. You have three seasons , so you have this spring early summer season where , you know , it rained over the winter and Southern California actually did well with rainfall. It was normal to even above normal. Even though we only had 3 or 4 storms , they all came at once. Uh , Northern California , not quite as lucky , but after a normal winter or even above normal winter , you see this period where the grass cures out , it dries out. It's called annual grasses , and it's very normal. And so you tend to get a lot of brush and grass fires in May and June , and then it sometimes settles down and then you're really relying on heat waves. So if we have big heat waves in July and August that will set up your second wildfire season. And that is a little more dangerous because it can spread into larger trees and burn longer and and faster and longer in terms of its coverage as well. So when you get those big fuels involved , it can last a long time. Now then you have the third season , which is the fall. That's the Santa Ana season where you've just had a hot , dry summer and anything is flammable in terms of vegetation.

S1: And there is a possibility that we may see more atmospheric river storms from El Nino , too , right?

S2: Yeah , that's a good comment. So whenever you excite the jet stream or the storm track that normally pays a visit in the winter , whenever you are able to bring that jet stream into California , you're more likely going to tap into that tropical moisture , not hurricanes , but tropical moisture near the equator , which is the source of the atmospheric rivers. We saw that even last year. And that's why last year's storms , we only had a few , but they packed the punch in November , December , and then again in February and a little bit in March. So the more opportunity you have with a storm track and and precipitation moving into California , the more likelihood that you're going to tap into some really rich tropical moisture or what we call atmospheric rivers.

S1: I've been speaking with Alex Tardy , founder of Weather Echo and formerly of the National Weather Service. Alex , thanks so much for breaking this down for us.

S2: Thank you very much. Very important topic.

S1: That's our show for today. I'm your host , Jade Hindman. Thanks for tuning in to Midday Edition. Be sure to have a great day on purpose , everyone.