IRI’s Climate Briefing for February

My first attempt at live-blogging. I hope to do this once a month. The International Research Institute for Climate and Society has its climate briefings on the third Wednesday of each month. The forecasts presented at the briefing are made available on the net assessment page usually by the following Thursday morning.

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.

• IRI’s Climate Briefing for March (0)
• A decade of multiseasonal climate forecasts (0)