el nino

The Climate Prediction Center (CPC), established by the National Weather Service (NWS), provides operational predictions of climate variability, real-time monitoring of climate and the required data bases, and assessments of the origins of major climate anomalies. The products cover time scales from a week to seasons, extending into the future as far as technically feasible, and cover the land, the ocean, and the atmosphere, extending into the stratosphere. The CPC is best known for its climate forecasts based on El Niño and La Niña conditions in the tropical Pacific.

Synopsis: El Niño is expected to strengthen and last through the Northern Hemisphere winter 2009-2010.

A majority of the model forecasts for the Niño-3.4 SST index suggest El Niño will reach at least moderate strength during the Northern Hemisphere fall (3-month Niño-3.4 SST index of +1.0oC or greater). Many model forecasts even suggest a strong El Niño (3-month Niño-3.4 SST index in excess of +1.5oC) during the fall and winter, but current observations and trends indicate that El Niño will most likely peak at moderate strength. Therefore, current conditions, trends, and model forecasts favor the continued development of a weak-to-moderate strength El Niño into the Northern Hemisphere fall 2009, with the likelihood of at least a moderate strength El Niño during the winter 2009-10.

Expected El Niño impacts during September-November 2009 include enhanced precipitation over the west-central tropical Pacific Ocean and the continuation of drier-than-average conditions over Indonesia. Temperature and precipitation impacts over the United States are typically weak during the Northern Hemisphere summer and early fall, generally strengthening during the late fall and winter.

In July 2009, the National Oceanic and Atmospheric Administration (NOAA) Climate Prediction Center reported that ocean temperatures in the central and eastern Pacific had shifted into El Niño—anomalously warm—conditions. El Niño conditions are evident in this sea surface temperature anomaly image based on data from the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) on NASA’s Aqua satellite on 26 July 2009. The current data are compared to long-term average temperatures (1985-1997) measured by the Advanced Very High Resolution Radiometers that have flown on several NOAA missions.

Places where temperatures were near normal are cream-colored, places where temperatures were warmer than normal are red, and places where temperatures were cooler than normal are blue. An area of dark red occupies the eastern Pacific off the coast of Peru and Ecaudor (north of Peru), indicating temperatures were much warmer than average. Meanwhile, across the Pacific, ocean temperatures around Indonesia were slightly cooler (light blue) than usual.

The Pacific is Earth’s largest ocean, so it shouldn’t be surprising that the Pacific’s primary climate pattern—the El Niño-Southern Oscillation, which climatologists shorten to “ENSO,&rdquo—is the single biggest influence on the average temperature, rainfall, and vegetation conditions in the tropics. ENSO includes an ocean component (the El Niño/La Niña pattern) as well as an atmospheric component, the Southern Oscillation.

Every 3-8 years, the prevailing easterly winds over the eastern equatorial Pacific weaken or reverse, water temperatures in the central and eastern Pacific climb, and rainfall declines over most tropical land areas. In 1997-98, an historically strong El Niño event contributed to devastating fires in Indonesia’s tropical forests. The fires released huge amounts of greenhouse gases into the atmosphere, and they led to the complete destruction of the Mentawai coral reefs west of Sumatra.

According to David Adamec, head of the Ocean Sciences Branch at NASA Goddard Space Flight Center, the development of El Niño ocean conditions isn’t a guarantee that a full-blown ENSO event will grip the climate by winter. So far, he says, the atmospheric component of the pattern, the Southern Oscillation, isn’t fully cooperating. As of July 26, the trade winds in the western Pacific (near Indonesia) had shifted direction and were blowing weakly toward the east (see NOAA wind anomaly graphic), but across the central and eastern Pacific, easterly trade winds were still of average or slightly above-average strength. For an ENSO event to fully develop, Adamec explains, the easterly trades will have to weaken across a much wider area of the Pacific than they have at present.

The impact of El Nino in the September-November period in 2009 is expected to include the continuation of drier-than-average conditions in Indonesia and enhanced precipitation in the west-central tropical Pacific Ocean, according to NOAA.

Current conditions, trends, and model forecasts favored the continued development of a weak-to-moderate strength El Nino into the Northern Hemisphere fall 2009, with the likelihood of at least a moderate strength El Nino during the winter 2009-10, according to an e-mailed press statement of US-based NOAA`s National Weather Service received by ANTARA News recently.

According to NOAA, El Nino is expected to strengthen and last through the Northern Hemisphere winter 2009-2010.

A weak El Nino continued during August 2009, as sea surface temperature (SST) remained above-average across the equatorial Pacific Ocean. Subsurface oceanic heat content (average temperatures in the upper 300m of the ocean) anomalies continued to reflect a deep layer of anomalous warmth between the ocean surface and the thermocline, particularly in the central Pacific.

"Enhanced convection over the western and central Pacific abated during the month, but the pattern of suppressed convection strengthened over Indonesia," according to the statement.

These oceanic and atmospheric anomalies reflect an ongoing weak El Nino.
A majority of the model forecasts for the Nino-3.4 SST index suggest El Nino will reach at least moderate strength during the Northern Hemisphere fall (3-month Nino-3.4 SST index of +1.0 degree Celsius or greater).

Many model forecasts even suggest a strong El Nino (3-month Nino-3.4 SST index in excess of +1.5 degree Celsius) during the fall and winter, but current observations and trends indicate that El Nino will most likely peak at moderate strength.

Therefore, current conditions, trends, and model forecasts favor the continued development of a weak-to-moderate strength El Nino into the Northern Hemisphere fall 2009, with the likelihood of at least a moderate strength El Nino during the winter 2009-10, according to NOAA`s El Nino Advisory.

Indonesia is currently experiencing the El Nino-induced drought, which among other things, has caused failures of some crop harvests, forest and peat fires, and water shortage in some regions.