The new set of forecasts show that conditions are expected to be neutral–as opposed to favoring another La Niña or an El Niño–through at least spring of next year.

I don’t have time to prep a more full report, as I’m getting ready for a reporting trip to the Philippines and Indonesia next month. However, I did want to highlight the flood data from the Dartmouth Flood Observatory that Ale Giannini showed us this afternoon. I had never heard of this valuable resource before, and certainly would have used it in my days as an infographics editor. Ale first put up a composite map of all the floods which have been recorded in 2008 (show here June events are numbered 62-75; click on the image to load the larger version).

Then she showed how a few rainfall anomaly plots for June compared:

Check out all of IRI’s forecasts here.

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How does La Niña—a cooling of the eastern Pacific Ocean—affect plant growth on the other side of the globe in Africa? La Niña occurs when strong trade winds blow across the Pacific Ocean. The winds push sun-warmed surface water west towards Australia. Cool water rises to replace the surface water in the east. As a result, the Pacific Ocean is cooler than normal in the east off South America and warmer in the west off Australia. Warm, moist air rises over the pool of warm water in the western Pacific, where it generates abundant rain in eastern Australia and Indonesia. The rising air travels east in the upper atmosphere, drops as cool, dry air over the eastern Pacific, and then blows west as the strong trade winds that drive La Niña.

Click for additional excerpt…

This circulation pattern is so large that it influences circulation the world over. Echoing the circulation over the Pacific, an identical pattern drives wind and rain in the Indian Ocean. Warm, moist air rises in the west, while cool, dry air sinks in the east. The effects of the Indian Ocean circulation pattern are evident in these images. The warm, moist air dropped heavy rain over southern Africa, where plants responded with gusto.

Reason I start with this is that for the last few months the IRI team has been forecasting a strong-to-moderate continuation of the phenomenon. This image, and one of Australia, also featured in NASA’s story, helps us to understand the real world effects of teleconnections. In Africa at least, the effects aren’t limited to greener landscapes. The increased chance of rains worried the World Health Organization enough to issue an alert in January for higher-than-normal number of malaria outbreaks in the region. You can read more about climate and malaria here.

Anyway, the briefing is starting. Let’s see what Tony and the gang have for us this month….

Brad starts it off. Wants to talk a bit about how difficult it is to communicate science topics, as they relate to climate.

Ecuador has been flooding, but it is it La Niña related? How about the southwest U.S., where there has been above average rainfall as well?

We don’t usually associate these with La Niña. And yet, for example, in a recent situation report issued by the United Nations Office for the Coordination of Humanitarian Affairs, the first line says

Due the La Nina phenomenon, over the past weeks, floods in Ecuador have increased, affecting 11 provinces or 50% of the territory.

Yowsa. This isn’t a very accurate statement. El Niño is usually responsible for such flooding. So he did a little back-of-the-envelope calculation. Brad looked at the past 50 years to see when it has been wet in this area and how this coincided with ENSO/La Niña. He found nine La Niña events that showed dryness in this region, and five that showed above average rains. So the current situation isn’t really that far from the norm in terms of the last half century.

Another story talks about looming drought in East Africa. So he looked at the climate outlook forum results from the region, and saw that the forecast showed predominantly near normal-conditions for the next three months (MAM). To take it a little further, we know the forecast skill is quite high for this region for OND. But for MAM, it’s not so good. So it seems a bit of a stretch to be making headlines like this.

Judy was at the COF where the forecast was given. She says the scientists didn’t say anything about drought in the region. But there was a large number of press present. In their minds, the yellow on the map meant very dry, very hot. Green means wet, lush. And that’s the message they took home. So it’s a problem of graphical interpretation, it’s a problem for us who provide the climate information, she says.

Now Tony steps up to the mic. His first slide says it all. “Moderate/Strong La Niña begins to weaken”.

La Niña is causing enhanced probability for below normal number of tropical cyclones in the northeast Pacific.

Visit the IRI’s net assessment page for the full spectrum of forecasts.

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Bear with me folks, I’m sure my speed writing will improve in time! Here goes…

Michael Bell starts with an overview for January…

• By Jan 2008 we saw a moderate La Niña event compared to past events.
• Negative SST anomalies in the west and central Pacific have strengthened but weakened in the eastern Pacific.
• Surface air temperature-in January very strong cold anomaly in central and southwest Asia. Some of these are in the lowest 10% of the climatological distribution for the regions. For example, the publicized cold snap in Afghanistan has resulted in 882 deaths and 130,000 livestock deaths as of Feb 14th. Also a rise in acute respiratory infections. We also see a pretty strong warm anomaly over eastern Canada, extending into northeast U.S.
• Precipitation anomalies- In indian Ocean we now see a strong negative anomaly whereas in December it was positive.

(He shows a cool animated graphic of outgoing longwave radiation.)

• On to precipitation teleconnections. How does it compare to patterns we normally associate with La Niña? In South America, we see below normal precipitation anomalies. Above normal in southern Africa, a hint of below normal in East Africa. Australia we see above normal precipitation in the east, drier in the west. In North America, we see dry conditions in southeastern U.S. We don’t see much going on in northern South America, where there’s usually a strong wet signal.

Now Tony with the forecasts…his title is “Moderate-Strong La Niña continue”

• Monthly average is -1.8 for Nino 3.4, which is strong according to NOAA’s definition.
• Last three months we see La Niña expanding to the west quite strongly. Very canonical looking pattern.
• This La Niña is on par strength-wise with those of the late 1990s and early 2000s, but not as strong as the 1988-89 one.
• Instead of seeing enhanced trade winds, we see winds radiating outward from the cold anomalies.
• There’s also a slug of deeper warmer water coming in from the west. Could this mean the end of La Niña? Not sure, because we also see a reinforcement of the cold anomalies in the east.
• Shuhua shows us that most of the modes showing strong-to-moderate La Niña for next few seasons.
• The probabilistic forecast for February shows a 95% chance for La Niña for the February-March-April season and by the middle of the year (June-July-August), we’re looking at a 45% chance for La Niña, 45% for neutral and a 10% chance for an El Nino.
• We see a typical La Niña signature in the seasonal climate forecast: dry in southeast Asia, slightly wet in northeastern Brazil, dry in southern U.S., dry in northeast Africa and west Asia.
• For precipitation forecasts, we start to see an above normal Sahel precipitation pattern for JJA season. So we see somewhat of a La Niña condition climate persisting into the next ENSO cycle.
• We also see a strong above-normal signal for temperatures in the southwestern U.S. that extends into the summer months.

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La Niña conditions continue in the central and eastern equatorial Pacific. Below-average sea surface temperatures (SSTs) exist from the west coast of South America to west of the dateline. Based on the latest observations and forecasts, there is a 96% probability of maintaining La Niña conditions over the coming season.

La Niña is characterized by unusually cold temperatures in the equatorial Pacific Ccean, and thus the opposite of El Niño, which is defined by unusually warm ocean temperatures in the same region.

IRI also has temperature and precipitation forecasts here.

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• IRI’s Climate Briefing for March (0)
• IRI’s Climate Briefing for February (0)