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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 November 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
Dec 2004 0 4% 8% 11% 9% 68%
Jan 2005 1 3% 12% 9% 39% 37%
Feb 2005 2 8% 24% 20% 16% 31%
Mar 2005 3 51% 15% 10% 14% 10%
Apr 2005 4 71% 7% 7% 3% 12%
May 2005 5 45% 27% 10% 12% 6%
Jun 2005 6 37% 26% 16% 11% 10%
Jul 2005 7 54% 20% 8% 4% 14%
Aug 2005 8 26% 21% 20% 13% 19%
Sep 2005 9 25% 22% 20% 20% 13%
Oct 2005 10 26% 20% 14% 19% 21%
Nov 2005 11 70% 9% 8% 4% 9%


NINO3
Month lead-time cold cool neutral warm hot
Dec 2004 0 28% 2% 7% 22% 42%
Jan 2005 1 32% 9% 3% 29% 27%
Feb 2005 2 24% 10% 16% 33% 18%
Mar 2005 3 27% 23% 7% 25% 17%
Apr 2005 4 15% 14% 25% 21% 26%
May 2005 5 27% 13% 20% 19% 21%
Jun 2005 6 19% 32% 17% 18% 13%
Jul 2005 7 20% 13% 20% 22% 24%
Aug 2005 8 13% 15% 29% 23% 21%
Sep 2005 9 15% 36% 14% 21% 13%
Oct 2005 10 31% 24% 12% 22% 11%
Nov 2005 11 25% 44% 9% 12% 10%


NINO3.4
Month lead-time cold cool neutral warm hot
Dec 2004 0 35% 4% 4% 28% 29%
Jan 2005 1 34% 4% 10% 39% 14%
Feb 2005 2 22% 6% 11% 31% 30%
Mar 2005 3 31% 8% 17% 13% 31%
Apr 2005 4 4% 6% 8% 16% 65%
May 2005 5 7% 17% 18% 28% 29%
Jun 2005 6 1% 10% 13% 55% 22%
Jul 2005 7 5% 6% 57% 16% 16%
Aug 2005 8 3% 10% 24% 36% 26%
Sep 2005 9 32% 33% 16% 14% 6%
Oct 2005 10 15% 45% 6% 23% 11%
Nov 2005 11 5% 24% 17% 36% 18%


NINO4
Month lead-time cold cool neutral warm hot
Dec 2004 0 28% 1% 4% 9% 58%
Jan 2005 1 23% 4% 8% 23% 43%
Feb 2005 2 27% 3% 2% 8% 60%
Mar 2005 3 25% 7% 6% 8% 54%
Apr 2005 4 28% 1% 6% 4% 62%
May 2005 5 22% 12% 11% 16% 39%
Jun 2005 6 22% 8% 13% 30% 27%
Jul 2005 7 5% 20% 26% 24% 26%
Aug 2005 8 9% 32% 32% 17% 10%
Sep 2005 9 33% 26% 15% 10% 16%
Oct 2005 10 22% 14% 11% 28% 24%
Nov 2005 11 10% 11% 11% 39% 28%