El Niño Update [20 Oct 2009]

ENSO Cycle: Recent Evolution, Current Status and Predictions

The following UPDATE is prepared by

Climate Prediction Center / NCEP –  19  October 2009

The latest weekly SST departures are:

• Niño 4   ~ 1.2ºC
• Niño 3.4  ~ 0.9ºC
• Niño 3 ~ 0.7ºC
• Niño 1+2 ~ 0.0ºC

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

SST Departures (°C) in the Tropical Pacific During the Last 4 Weeks
During the last 4-weeks, equatorial SSTs were at least 1.0°C above average between 165°E and 140°W and in small areas in the eastern Pacific.

Global SST Departures (°C)
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 subtropics.

Weekly SST Departures (°C) for the Last Four Weeks
for the Last Four Weeks•During the last four weeks, equatorial SST anomalies strengthened across the central Pacific Ocean.•During the last month, equatorial SST anomalies decreased over parts of the eastern Pacific and increased over the central Pacific.

Atmospheric Circulation over the North Pacific & North America During the Last 60 Days
During mid August through September, an anomalous trough was prevalent in the North Pacific Ocean/Gulf of Alaska. During September, an anomalous ridge was present downstream, focused over Canada and the northern United States. The pattern also featured a weak trough over the central U.S., which contributed to below-average temperatures in the region, while the northern U.S. and Canada remained warmer-than-average. Recently, an anomalous ridge has developed in the Gulf of Alaska with a downstream trough contributing to below-average temperatures across much of the U.S. and Canada.

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 greater than +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 15 Oct 2009).

SST Outlook: NCEP CFS Forecast Issued 18 October 2009
The CFS ensemble mean predicts El Niño will last through Northern Hemisphere winter 2009-10.

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 and Archive]