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Probabilistic Forecasts 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" (dark blue), "cool" (light blue), "neutral" (green), "warm" (orange), and "hot" (red) conditions, and the horizontal lines indicate the climatological probabilities (20% for each category). The forecasts were produced using January 2003 observed sea-surface temperatures, and with version 3.05 of the SPEP (Statistical Probabilistic ENSO Predictions) model.
NINO1&2
Month lead-time cold cool neutral warm hot
Feb 2003 0 5% 28% 29% 23% 15%
Mar 2003 1 37% 22% 15% 17% 10%
Apr 2003 2 29% 22% 18% 22% 9%
May 2003 3 33% 24% 10% 22% 11%
Jun 2003 4 39% 13% 20% 14% 14%
Jul 2003 5 41% 15% 15% 18% 11%
Aug 2003 6 59% 13% 6% 12% 10%
Sep 2003 7 48% 26% 7% 11% 9%
Oct 2003 8 55% 22% 4% 8% 11%
Nov 2003 9 64% 14% 6% 4% 11%
Dec 2003 10 59% 18% 7% 6% 10%
Jan 2004 11 37% 32% 14% 7% 11%


NINO3
Month lead-time cold cool neutral warm hot
Feb 2003 0 1% 3% 11% 27% 58%
Mar 2003 1 3% 5% 17% 34% 42%
Apr 2003 2 10% 15% 27% 22% 27%
May 2003 3 29% 13% 15% 18% 26%
Jun 2003 4 23% 15% 16% 18% 28%
Jul 2003 5 21% 19% 17% 17% 27%
Aug 2003 6 23% 14% 17% 15% 31%
Sep 2003 7 30% 15% 10% 21% 24%
Oct 2003 8 30% 10% 15% 24% 20%
Nov 2003 9 31% 10% 18% 20% 21%
Dec 2003 10 25% 16% 16% 20% 23%
Jan 2004 11 19% 20% 19% 21% 21%


NINO3.4
Month lead-time cold cool neutral warm hot
Feb 2003 0 0% 0% 9% 35% 56%
Mar 2003 1 0% 10% 21% 14% 55%
Apr 2003 2 9% 19% 18% 18% 36%
May 2003 3 22% 14% 18% 15% 31%
Jun 2003 4 22% 20% 16% 18% 24%
Jul 2003 5 29% 20% 20% 17% 15%
Aug 2003 6 33% 19% 19% 15% 15%
Sep 2003 7 38% 15% 17% 16% 13%
Oct 2003 8 31% 18% 19% 18% 14%
Nov 2003 9 29% 25% 16% 16% 15%
Dec 2003 10 24% 23% 21% 17% 15%
Jan 2004 11 27% 20% 19% 19% 14%


NINO4
Month lead-time cold cool neutral warm hot
Feb 2003 0 0% 0% 21% 32% 47%
Mar 2003 1 2% 9% 26% 22% 41%
Apr 2003 2 1% 8% 19% 33% 39%
May 2003 3 2% 10% 23% 29% 36%
Jun 2003 4 8% 11% 22% 25% 35%
Jul 2003 5 10% 13% 20% 22% 34%
Aug 2003 6 16% 23% 15% 12% 34%
Sep 2003 7 18% 19% 15% 21% 27%
Oct 2003 8 21% 18% 17% 20% 24%
Nov 2003 9 29% 17% 20% 23% 12%
Dec 2003 10 23% 20% 18% 20% 20%
Jan 2004 11 29% 17% 24% 16% 13%