1. The El Niño/ Southern Oscillation (ENSO) Cycle Lab
Michelle L’Heureux
NOAA/NWS/NCEP/Climate Prediction Center

2. Instructions (1) Download the latest weekly ENSO ppt/pdf from:
(2) Use the weekly ENSO update to answer the Critical Questions and guide your briefing.
Other resources are available on the ENSO web page:
ENSO Composites:
ENSO Boxplots:
Monthly ENSO Diagnostics Discussion:

3. Critical Questions (1) What is the current status of ENSO?
(2) What are the current oceanic conditions (surface and subsurface) in the equatorial Pacific?
(3) What is the latest weekly value of the Nino-3.4 index?
(4) What is the latest ONI value?
(5) What are the current atmospheric conditions (winds, convection) over the equatorial Pacific?
(6) Describe the recent pattern over the North Pacific Ocean. Is the pattern consistent with La Nina or El Nino? How so?
(7) What does the model guidance indicate?
(8) What is the forecasted evolution of ENSO?
(9) What are the potential impacts on U.S. precipitation and temperature for the upcoming 3mo. season?

4. ENSO Cycle: Recent Evolution, Current Status and Predictions
Update prepared by
Climate Prediction Center / NCEP
November 2, 2009

5. Outline Overview Recent Evolution and Current Conditions
Oceanic Niño Index (ONI) – “Revised December 2008”
Pacific SST Outlook
U.S. Seasonal Precipitation and
Temperature Outlooks
Summary
El Niño Composites

6. 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

7. Recent Evolution of Equatorial Pacific SST Departures (oC)
Time
During November February 2009, negative sea surface temperature (SST) anomalies covered the central and east-central equatorial Pacific Ocean.
Since the beginning of June 2009, SST anomalies have been at least +0.5°C across most of the equatorial Pacific.
Recently, SST anomalies have increased across much of the equatorial Pacific.
Longitude

8. Niño Region SST Departures (oC) Recent Evolution
The latest weekly SST departures are:
Niño ºC
Niño ºC
Niño ºC
Niño ºC

9. SST Departures (oC) 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.

10. 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 subtropics.

11. Weekly SST Departures (oC) 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.

12. 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.

13. Sub-Surface Temperature Departures (oC) in the Equatorial Pacific
During September – October 2009, temperature anomalies increased and expanded eastward in the central equatorial Pacific at thermocline depth, 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 150m depth.
Time
Most recent pentad analysis
Longitude

14. 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, Papua New Guinea, and over the western tropical Pacific Ocean.
Low-level (850-hPa) westerly anomalies were observed over parts of the western and central equatorial Pacific.
Upper-level (200-hPa) easterly anomalies were observed across most of the equatorial Pacific.

15. Atmospheric Circulation over the North Pacific & North America During the Last 60 Days
200-hPa Wind
500-hPa Height & Anoms.
925-hPa Temp. Anoms. (oC)
During September, an anomalous trough over the northeast North Pacific, and an anomalous ridge downstream over Canada and the northern United States contributed to warmer-than-average conditions over the northern U.S. and Canada. In the first half of October an anomalous ridge developed over Alaska, with a downstream trough and below- average temperatures over Canada and the western and northern U.S. Recently, the pattern has become more zonal with a weak trough over the central U. S. and below average temperatures in the central and southeastern parts of the nation.

16. Weekly Heat Content Evolution in the Equatorial Pacific
During November 2008 – January 2009, negative heat content anomalies strengthened in the central and eastern equatorial Pacific as La Niña conditions redeveloped.
The negative anomalies weakened during January-March 2009, with positive anomalies becoming established in late March.
In April 2009, the combined effects of an oceanic Kelvin wave and weaker-than-average easterly trade winds contributed to an increase in the upper-ocean heat content anomalies across the Pacific Ocean.
Since April 2009, heat content anomalies have remained above-average, but there has been considerable month-to-month variability due to Kelvin wave activity.
Recently, the downwelling phase of a Kelvin wave is evident.
Time
downwelling
Oceanic Kelvin waves have alternating warm and cold phases. The warm phase is indicated by dashed lines. Down-welling and warming occur in the leading portion of a Kelvin wave, and up-welling and cooling occur in the trailing portion.
Longitude

17. Low-level (850-hPa) Zonal (east-west) Wind Anomalies (m s-1)
Westerly wind anomalies (orange/red shading).
Easterly wind anomalies (blue shading).
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 western and east-central Pacific Ocean.
Time
Longitude

18. Outgoing Longwave Radiation (OLR) Anomalies
Drier-than-average conditions (orange/red shading)
Wetter-than-average conditions (blue shading)
During July 2009, convection was enhanced near the Date Line and over the western Pacific.
Since mid-May 2009, convection has remained mostly suppressed over the eastern Indian Ocean and Maritime Continent.
Convection has generally been enhanced over the western Pacific since late August.
Time
Longitude

19. ONI (oC): Evolution since 1950
The most recent ONI value (July – September 2009) is +0.8oC.
El Niño
neutral
La Niña

20. Pacific Niño 3.4 SST Outlook
Most ENSO models indicate El Niño will continue through the Northern Hemisphere winter
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
Figure provided by the International Research Institute (IRI) for Climate and Society (updated 15 Oct 2009).

21. SST Outlook: NCEP CFS Forecast Issued 1 November 2009
The CFS ensemble mean (heavy blue line) predicts El Niño will last at least through Northern Hemisphere spring 2010.

22. U. S. Seasonal Outlooks November 2009 – January 2010
Temperature
Precipitation
The seasonal outlooks combine the effects of long-term trends, soil moisture, and, when appropriate, the ENSO cycle.

23. Critical Questions (1) What is the current status of ENSO?
(2) What are the current oceanic conditions (surface and subsurface) in the equatorial Pacific?
(3) What is the latest weekly value of the Nino-3.4 index?
(4) What is the latest ONI value?
(5) What are the current atmospheric conditions (winds, convection) over the equatorial Pacific?
(6) Describe the recent pattern over the North Pacific Ocean. Is the pattern consistent with La Nina or El Nino? How so?
(7) What does the model guidance indicate?
(8) What is the forecasted evolution of ENSO?
(9) What are the potential impacts on U.S. precipitation and temperature for the upcoming 3mo. season?

24. El Nino Composites for November-January

25. Instructions (1) Download the latest weekly ENSO ppt/pdf from:
(2) Use the weekly ENSO update to answer the Critical Questions and guide your briefing.
Other resources are available on the ENSO web page:
ENSO Composites:
ENSO Boxplots:
Monthly ENSO Diagnostics Discussion: