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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

MAY 2009

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

ENSO Alert System Status: El Niño Watch      

Outlook:  

            Conditions are favorable for a transition from ENSO-neutral to El Niño conditions during June − August 2009. 

Discussion:    

ENSO -neutral conditions persisted across the equatorial Pacific Ocean during May 2009. However, sea surface temperatures (SST) departures increased for the fifth consecutive month, with above-average temperatures extending across the equatorial Pacific Ocean by the end of May (Fig. T18).  Accordingly, the monthly SST indices ranged between +0.3° to +0.6°C in all four Niño regions (Table T2).  Subsurface oceanic heat content anomalies (average temperatures in the upper 300m of the ocean) also continued to increase in response to a large area of above-average temperatures (+1° to +3°C) near thermocline depth (Fig. T17).  These surface and subsurface oceanic anomalies typically precede the development of El Niño. 

From early 2007 through April 2009, enhanced low-level easterly winds persisted near the Date Line, interrupted only briefly by Madden- Julian Oscillation (MJO) activity (Fig. T20).  However, during May 2009, both the lower-level equatorial winds were near-average in that region despite the absence of the MJO.  Also, suppressed convection expanded westward along the equator from the Date Line to Indonesia (Fig. T25).  The recent oceanic and atmospheric anomalies are consistent with ENSO-neutral conditions, but also reflect the evolution towards a potential El Niño. 

There continues to be considerable spread in the model forecasts for the Niño-3.4 region (Figs. F1-F13).  All statistical models predict ENSO -neutral conditions will continue for the remainder of 2009.  However, most dynamical models, including the NCEP Climate Forecast System, predict the onset of El Niño during June − August 2009.  Current observations, recent trends, and the dynamical model forecasts indicate that conditions are favorable for a transition from ENSO -neutral to El Niño conditions during June − August 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).