El Niño Update [28 Sept 2009]

ENSO Cycle: Recent Evolution, Current Status and Predictions

The following UPDATE is prepared by

Climate Prediction Center / NCEP – 28 Sept 2009

The latest weekly SST departures are:

• Niño 4   ~ 0.8ºC
• Niño 3.4  ~ 0.8ºC
• Niño 3 ~ 0.7ºC
• Niño 1+2 ~ -0.1ºC

El Niño Map. [SOURCE: NOAA/ Climate Prediction Center / NCEP]

Niño Region SST Departures (ºC) –  Recent Evolution

Highlights

SST Departures (°C) in the Tropical Pacific During the Last 4 Weeks
During the last 4-weeks, equatorial SSTs were at least1.0°C above average across much of the central and eastern Pacific.

Global SST Departures  (ºC)
During the last four weeks, equatorial SSTs were above-average in the Pacific and Indian Oceans. Also, above-average SSTs covered large areas of the Northern Hemisphere mid-to-high latitudes.

Weekly SST Departures (ºC) for the Last Four Weeks

• During the last four weeks, SST anomalies remained positive across the equatorial Pacific Ocean.
• During the last month, there was little change in the equatorial SST anomalies.

Sub-Surface Temperature Departures (ºC) in the Equatorial Pacific

• In the first half of September 2009, temperature anomalies increased in the eastern Pacific due to the downwelling phase of a Kelvin wave.
• The most recent period shows a continuation of positive anomalies across the equatorial Pacific, with the largest values between 50-150m depth.

Atmospheric Circulation over the North Pacific & North America During the Last 60 Days
During late July through September, an anomalous trough was prevalent in the central North Pacific Ocean. During September, an anomalous ridge was present downstream, focused over Canada and the northern United States. The pattern also featured a trough over the southern U.S., which contributed to cooling in the region, while the northern U.S. and Canada remained warmer-than-average.

Pacific Niño 3.4 SST Outlook

• Most ENSO models indicate El Niño will continue through the Northern Hemisphere winter 2009-10.
• The models disagree on the eventual strength of El Niño (SST anomalies ranging from +0.5°C to +2.0°C), but a majority indicate at least a moderate strength El Niño (greater than +1.0°C) during November-December-January 2009-10.

Figure provided by the International Research Institute (IRI) for Climate and Society (updated 14 Sept 2009).

ONI Evolution
The most recent ONI value (June –August 2009) is +0.7oC.

Summary:

• El Niño is present across the equatorial Pacific Ocean.
• Sea surface temperatures (SST) were at least 1.0ºC above-average across much of the central and east-central equatorial Pacific.
• Based on current observations and dynamical model forecasts, El Niño is expected to strengthen and last through Northern Hemisphere winter 2009-10.

Information and images on this page are sourced from Climate Prediction Center/NCEP/NOAA.

Related Links:

• Recognizing El Niño
• El Niño and La Niña: Tracing the Dance of Ocean and Atmosphere
• TAO Diagrams
• El Niño Forecasts

El Niño Updates:

• El Niño [Main Page]

• El Niño Update [21 Sept 2009]

• El Niño Update [14 Sept 2009]
• El Niño Update [8 Sept 2009]
• El Niño Update [31 Aug 2009]
• El Niño Update [17 Aug 2009]
• El Niño Update – 10 August 2009
• El Niño Update – 3 August 2009
• El Niño Update – 27 July 2009

• El Niño Update – 20 July 2009
• El Niño Update # 1
• El Niño conditions is in progress —NOAA
• El Niño event almost certain: BOM
• El Niño could develop June – August 2009
• World Now
• 2009 Hurricane Season