El Niño Update [16 Nov 2009]

ENSO Cycle: Recent Evolution, Current Status and Predictions

The following UPDATE is prepared by

Climate Prediction Center / NCEP –  16 November 2009

The latest weekly SST departures are:

• Niño 4   ~  1.5ºC
• Niño 3.4  ~  1.7ºC
• Niño 3 ~ 1.2ºC
• Niño 1+2 ~ 0.5ºC

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

SST Departures (°C) in the Tropical Pacific During the Last 4
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 140°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 across much of the central and eastern Pacific.

Central & Eastern Pacific Upper-Ocean (0-300 m) Weekly Heat Content Anomalies
Since April 2009, the upper-ocean heat content has been above average across
the eastern half of the equatorial Pacific Ocean. The heat content was previously below-average from mid-August 2008 through March 2009, with a minimum reached in late December 2008.

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

• During late September – early November 2009, temperature anomalies at thermocline depth increased and expanded eastward across the central and east-central equatorial Pacific, in response to the downwelling phase of an oceanic Kelvin wave.

• The most recent period (below) shows a continued eastward expansion of positive anomalies in the equatorial Pacific near 50 – 150m depth.

Tropical OLR and Wind Anomalies During the Last 30 Days

• Positive OLR anomalies (suppressed convection and precipitation, red shading) were present over Indonesia, Malaysia, Papua New Guinea, and Australia. Negative OLR anomalies (enhanced convection and precipitation, blue shading) were located over the western tropical Pacific Ocean just southeast of Papua New Guinea.

• Low-level (850-hPa) westerly anomalies were observed over the 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.

Atmospheric Circulation over the North Pacific & North America During the Last 60 Days
From mid-September through October, anomalous troughing was prevalent over the North Pacific Ocean. During October, the pattern of below-average heights became more zonal over the mid-latitudes and an anomalous ridge developed over the higher latitudes. This pattern contributed to below-average temperatures across Canada and much of the U.S. Since early November, the anomalous zonal pattern of below-average heights at mid-latitudes has been replaced by anomalous ridges with below-average heights across the northernmost latitudes. This pattern has led to above-average temperatures across much of Canada and the United States.

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 the Northern Hemisphere winter 2009-10.

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

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]