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El Niño weakens from strong to moderate

By: Dr. Jeff Masters, 2:32 PM GMT on February 03, 2010

El Niño is weakening. Ocean temperatures over the Eastern and Central Pacific have gradually cooled over the past few weeks, and it now appears that the El Niño event of 2009 - 2010 has peaked. Ocean temperatures in the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region", crossed below the 1.5°C threshold for a strong El Niño into the "moderate" range in mid-January, and were 1.2°C above average on January 31, according to the Australian Bureau of Meteorology. If temperatures decline further into the 0.5°C - 1.0°C above average range, this will be a "weak" El Niño. The peak warmth of this event appears to have been late December - early January (Figure 1).

Figure 1. Departure of sea surface temperature from average for the Equatorial Pacific Ocean from March 2009 (when La Niña conditions were present) to January 2010. The strongest El Niño conditions were observed December 2009 - January 2010, when temperatures as much as 2 - 2.5°C (dark orange colors) were observed between longitudes 150°W - 170°W. Image credit: NOAA Climate Prediction Center.

The El Niño forecast
Though El Niño appears to have peaked, the decline in SSTs over the Equatorial Pacific may slow and possibly reverse in February, thanks to a burst of stronger-than-average surface westerly winds that has developed near the Date Line. This westerly wind burst is driving a new Kelvin wave of sub-surface warm water towards the coast of South America, which will act to reinforce El Niño over the next month or so. This new Kelvin wave is not as strong as the previous one that propagated eastward over the last few months of 2009, which pushed El Niño over the "strong" threshold. Once the new Kelvin wave subsides in March, it is possible that there will be more westerly wind bursts that will act to drive new Kelvin waves that will reinforce El Niño into the summer. However, El Niño events typically die out in the spring, and most of the El Niño computer forecast models (Figure 2) are predicting an end to El Niño by summer. Note that the last time we had a strong El Niño event--the record El Niño of 1997 - 1998--the event ended very abruptly in May, and a La Niña event developed by the 1998 hurricane season. This resulted in a very active 1998 hurricane season (14 named storms, 10 hurricanes, and 3 major hurricanes, including Category 5 Hurricane Mitch). The recent weakening of El Niño is a likely sign that there will not be El Niño conditions for the coming hurricane season. Only once since 1950 has an El Niño event lasted through two full hurricane seasons, and I don't expect that will occur this time, either. Given that since 1995, the Atlantic has been in an active hurricane period, except for in El Niño years, a more active than normal hurricane season is likely in 2010.

Figure 2. Forecasts made in late January of El Niño from a suite of high-powered global dynamical models and simpler statistical models. Of the dynamical models, 5 are forecasting neutral El Niño conditions by hurricane season (ASO, August-September-October), 2 are forecasting La Niña, and only 1 is forecasting El Niño. For the statistical models, these numbers are 4 neutral, 1 La Niña, and 3 El Niño. Image credit: Columbia University's IRI.

Portlight looking for tents for Haiti
Portlight.org disaster-relief continues to make great progress in Haiti getting aid to those who need it. Portlight has managed to get $100,000 in donated durable medical equipment into Haiti so far, at a cost of just $4500. Paul Timmons, leader of the Portlight relief efforts, wrote this in the latest Portlight.org blog:

OK...gonna make this quick...but we...and by 'we' I mean all of us....have done something that the Federal government has not been able to do: we have opened a direct pipeline for the shipment, delivery and distribution of goods from our Atlanta warehouse directly to our secured location near Port-au-Prince...I have had two calls from USAID officials this morning asking "How'd ya do it?"...and "Can we use it?"

we are making a difference, y'all....

Figure 3. Paul Timmons of Portlight surveys medical beds and crutches being readied for shipment to Haiti.

So, please visit the Portlight.org blog to learn more and to donate. Floodman's blog has the latest info on Portlight's plan for Haitian relief. A few highlights:

Paul Timmons, head of Portlight, has been interviewed by NBC Nightly News at our Atlanta location for a story that will follow one of our shipments from the Atlanta warehouse to its distribution in Haiti. This story will be aired in several parts starting late this week. When scheduling information is given to us we will post it here; tune in and see Paul!

Ron will be on The Barometer Bob Show Thursday night outlining our ongoing efforts in Haiti. We here at Portlight want to thank Bob for his continuing support; he has been a good friend to Portlight and we appreciate his efforts!

On site:
Our primary site coordinator, Richard Lumarque, has been in Haiti for 5 days and has been moving fairly freely from the base at the Quisqueya University; he has been looking at properties that have been offered for tent cities in the Leogane area as well as making contact with a number of people that have been in contact with us here in the US about specific issues. He has contacted the village leaders at Dufort and is working to arrange food deliveries to them.

Further, the latest shipment is expected to be in the Dominican Republic on Thursday. Given the overland route required by the damage in Haiti, we hope to have this shipment in Haiti late in the day on Friday. The delivery and distribution of this shipment will be covered by NBC Nightly News as a part of the aforementioned piece.

We have several additional shipments queued up for transport, including the remainder of the donation from H&H Wholesalers and these will be sent in the next several days; we are investigating a number of additional shipping opportunities that will facilitate quicker lead and delivery times.

Paul will also be on KFPA radio in Berkley, CA at 2pm PST Friday. Tune into http://www.kpfa.org/pushing-limits to hear the show. Paul also appeared on WBAI in New York City on January. Check out their archives to hear the interview.

Next post
I'll have a new post on Friday.

Jeff Masters

The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.