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ENSO Forecast Discussion

ENSO and SST Model Forecasts

Canonical Correlation Model
Nino 3.4 Region: Historical  F1
Nino 3.4 Region: 0-4 Season  F2

NCEP Coupled Model
Eq. Pac. SST & Anomalies  F3
Nino 3 & Nino 3.4 Region  F4

NCEP Markov Model
Eq. Pac. SST & Anomalies  F5
Nino 3.4 Region  F6

LDEO Model
Eq. Pac. SST & Wind Stress Anoms  F7
Nino 3 Region  F8

Linear Inverse Modeling
Global Tropical SST Anomalies  F9
Nino 3.4 Region: Historical  F10

Scripps/MPI Hybrid Coupled Model
Eq. Pac. SST & Anomalies  F11

ENSO-CLIPER Model
All Nino Regions & SOI  F12

IRI Compilation of Forecasts
Nino3.4 Region  F13

Forecast Forum

SEPTEMBER 2008

The CPC and the contributors to the Forecast Forum caution potential users of this predictive information that they can expect only modest skill.

     Outlook:  

            ENSO-neutral conditions are expected to continue into early 2009.   

      Discussion:    

ENSO-neutral conditions continued during September 2008, as sea surface temperatures (SSTs) remained near-average in the east-central equatorial Pacific Ocean .  SSTs remained slightly below-average in the central Pacific, and slightly above-average in the eastern Pacific (Fig. T18).  From west to east, the monthly SST index values range from −0.4°C in the Niño-4  region to +0.7°C in the Niño 1+2 region (Table T2).  The subsurface oceanic heat content (average temperatures in the upper 300m of the ocean) continued to decrease in response to the strengthening of negative temperature anomalies at thermocline depth in the east-central Pacific (Fig. T17). 

Although ENSO-neutral conditions have been in place since June 2008, the atmospheric circulation over the western and central tropical Pacific continues to reflect lingering aspects of La Niña. The MJO accentuated this signal during early-to-mid September, and suppressed it during the latter part of the month. The combined monthly average signal featured enhanced low-level easterly winds and upper-level westerly winds in the central Pacific (Figs. T20 and T21), with convection enhanced over Indonesia and suppressed over the central Pacific (Fig. T25).  Overall, the ocean-atmosphere system remains consistent with ENSO-neutral conditions. 

Most of the dynamical and statistical SST forecasts for the Niño 3.4 region indicate a continuation of ENSO-neutral conditions (−0.5°C to 0.5°C in the Niño-3.4 region) into the first half of 2009 (Figs. F1- F13).  While the model spread continues to include possibilities ranging from El Niño to La Niña, the recent decrease in subsurface and surface temperatures favors a return to La Niña over the development of El Niño. However, based on current atmospheric and oceanic conditions, recent trends, and model forecasts, ENSO-neutral conditions are expected to continue into early 2009.

Weekly updates of oceanic and atmospheric conditions are available on the Climate Prediction Center homepage (El Niño/La Niña Current Conditions and Expert Discussions).