El Niño Update [10 Nov 2009]

ENSO Cycle: Recent Evolution, Current Status and Predictions

The following UPDATE is prepared by

Climate Prediction Center / NCEP –  9 November 2009

The latest weekly SST departures are:

• Niño 4   ~  1.6ºC
• Niño 3.4  ~  1.7ºC
• Niño 3 ~ 1.3ºC
• Niño 1+2 ~ 0.4ºC
  

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, SSTs were at least 1.0°C above average across much of the equatorial Pacific and more than 2.0°C above average between 175°E and 160°W.

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

• During the last four weeks, equatorial SST anomalies strengthened across the central and eastern Pacific Ocean.
• During the last 30 days, equatorial SST anomalies increased in much of the central and eastern Pacific.

Tropical OLR and Wind Anomalies During the Last 30 Days

• Positive OLR anomalies (suppressed convection and precipitation, red shading) were present over Indonesia, Malaysia, and Australia. Negative OLR anomalies (enhanced convection and precipitation, blue shading) were located across the northern Philippines and over the western tropical Pacific Ocean.
• Low-level (850-hPa) westerly anomalies were observed over parts of the western and east-central equatorial Pacific.
• Upper-level (200-hPa) easterly anomalies were observed across most of the equatorial Pacific. Anomalous anticyclones were evident in the subtropics of both hemispheres, which is consistent with El Niño.

Sub-Surface Temperature Departures (°C) in the Equatorial Pacific

• During mid September –October 2009, temperature anomalies increased and expanded eastward in the central equatorial Pacific at thermoclinedepth, due to the downwelling phase of a Kelvin wave.
• The most recent period (below) shows a continued eastward expansion of positive anomalies in the central Pacific near 100-150m depth.

Atmospheric Circulation over the North Pacific & North America During the Last 60 Days
In late September and early October, an anomalous ridge developed over the Gulf of Alaska, with a downstream trough and below-average temperatures over parts of the U.S. During mid October, the pattern became more zonal with an anomalous trough evident over the mid-latitudes and an anomalous ridge over the higher latitudes. This pattern contributed to below-average temperatures across Canada and the eastern half of the U.S. Recently, anomalous ridges emerged over the eastern North Pacific and eastern U.S. leading to above-average temperatures over the western and eastern U.S.

Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m s^-1)

• Since April 2009, the MJO has been weak.
• Since May 2009, westerly wind anomalies have covered large portions of the equatorial Pacific, except near the Date Line.
• Recently, the largest westerly wind anomalies have been observed across the eastern Pacific Ocean.

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

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 continue to strengthen and last through at least theNorthern Hemisphere winter 2009-10.

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 Update [2 Nov 2009]
• El Niño [Main Page and Archive]