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Probabilistic Predictions of ENSO Indices Using Statistical Models

The forecast probabilities averaged across 7 models are presented in the graphs and tables below. The graphs show the probabilities for "cold" (blue), "neutral" (green), and "hot" (red) conditions, and the horizontal lines indicate the climatological probabilities (25% each for "cold" and "hot", and 50% for "neutral"). The forecasts were produced using January 2004 observed sea-surface temperatures, and with version 4.01 of the SPEP (Statistical Probabilistic ENSO Predictions) model.

NINO1&2
Month lead-time cold cool neutral warm hot
Feb 2004 0 3% 4% 9% 4% 79%
Mar 2004 1 14% 8% 16% 9% 53%
Apr 2004 2 12% 20% 9% 11% 48%
May 2004 3 46% 20% 5% 8% 22%
Jun 2004 4 61% 15% 7% 6% 11%
Jul 2004 5 21% 7% 11% 18% 44%
Aug 2004 6 6% 7% 10% 18% 59%
Sep 2004 7 12% 7% 10% 12% 59%
Oct 2004 8 54% 5% 8% 24% 9%
Nov 2004 9 2% 1% 15% 53% 29%
Dec 2004 10 35% 18% 6% 32% 9%
Jan 2005 11 30% 34% 3% 26% 6%


NINO3
Month lead-time cold cool neutral warm hot
Feb 2004 0 9% 11% 24% 32% 25%
Mar 2004 1 6% 12% 23% 31% 28%
Apr 2004 2 30% 11% 12% 10% 36%
May 2004 3 27% 19% 20% 14% 19%
Jun 2004 4 46% 11% 9% 12% 22%
Jul 2004 5 47% 12% 9% 11% 20%
Aug 2004 6 46% 12% 6% 15% 22%
Sep 2004 7 41% 16% 16% 15% 12%
Oct 2004 8 20% 27% 18% 22% 13%
Nov 2004 9 34% 26% 22% 12% 7%
Dec 2004 10 11% 12% 31% 23% 24%
Jan 2005 11 33% 26% 14% 16% 11%


NINO3.4
Month lead-time cold cool neutral warm hot
Feb 2004 0 31% 8% 19% 34% 7%
Mar 2004 1 21% 21% 46% 8% 4%
Apr 2004 2 19% 14% 21% 21% 24%
May 2004 3 23% 5% 19% 20% 34%
Jun 2004 4 13% 9% 9% 22% 48%
Jul 2004 5 32% 8% 16% 16% 28%
Aug 2004 6 7% 35% 18% 12% 29%
Sep 2004 7 31% 19% 11% 14% 26%
Oct 2004 8 7% 26% 20% 20% 27%
Nov 2004 9 12% 30% 6% 23% 29%
Dec 2004 10 8% 8% 11% 32% 42%
Jan 2005 11 7% 11% 26% 23% 32%


NINO4
Month lead-time cold cool neutral warm hot
Feb 2004 0 32% 4% 31% 28% 5%
Mar 2004 1 33% 11% 23% 22% 11%
Apr 2004 2 32% 16% 15% 19% 19%
May 2004 3 31% 16% 20% 16% 16%
Jun 2004 4 27% 14% 14% 11% 34%
Jul 2004 5 15% 20% 21% 22% 23%
Aug 2004 6 7% 9% 28% 20% 36%
Sep 2004 7 23% 5% 19% 21% 33%
Oct 2004 8 7% 12% 22% 24% 35%
Nov 2004 9 12% 5% 5% 38% 39%
Dec 2004 10 18% 7% 9% 30% 36%
Jan 2005 11 7% 24% 21% 29% 21%