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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 July 2003 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
Aug 2003 0 15% 30% 23% 16% 2%
Sep 2003 1 5% 8% 15% 18% 39%
Oct 2003 2 27% 22% 13% 10% 13%
Nov 2003 3 3% 2% 10% 35% 36%
Dec 2003 4 8% 7% 19% 8% 44%
Jan 2004 5 72% 1% 11% 1% 0%
Feb 2004 6 79% 2% 2% 3% 1%
Mar 2004 7 80% 3% 1% 1% 0%
Apr 2004 8 80% 1% 3% 1% 1%
May 2004 9 69% 3% 2% 4% 8%
Jun 2004 10 61% 21% 2% 1% 1%
Jul 2004 11 75% 4% 1% 5% 0%


NINO3
Month lead-time cold cool neutral warm hot
Aug 2003 0 29% 2% 2% 48% 5%
Sep 2003 1 12% 7% 5% 18% 43%
Oct 2003 2 8% 5% 5% 16% 50%
Nov 2003 3 3% 4% 13% 9% 57%
Dec 2003 4 16% 7% 13% 19% 31%
Jan 2004 5 14% 1% 3% 8% 61%
Feb 2004 6 10% 8% 14% 13% 40%
Mar 2004 7 26% 12% 8% 19% 21%
Apr 2004 8 74% 3% 2% 1% 7%
May 2004 9 50% 11% 15% 8% 2%
Jun 2004 10 69% 5% 4% 4% 4%
Jul 2004 11 25% 19% 21% 15% 6%


NINO3.4
Month lead-time cold cool neutral warm hot
Aug 2003 0 29% 2% 14% 25% 17%
Sep 2003 1 28% 2% 5% 25% 25%
Oct 2003 2 27% 3% 10% 24% 22%
Nov 2003 3 28% 1% 8% 25% 23%
Dec 2003 4 28% 3% 9% 27% 32%
Jan 2004 5 28% 4% 7% 28% 33%
Feb 2004 6 26% 13% 7% 18% 37%
Mar 2004 7 28% 5% 11% 17% 40%
Apr 2004 8 58% 19% 4% 4% 15%
May 2004 9 9% 26% 21% 25% 19%
Jun 2004 10 64% 10% 3% 8% 15%
Jul 2004 11 40% 34% 5% 5% 16%


NINO4
Month lead-time cold cool neutral warm hot
Aug 2003 0 23% 4% 9% 33% 32%
Sep 2003 1 19% 12% 21% 22% 27%
Oct 2003 2 22% 12% 19% 20% 27%
Nov 2003 3 22% 5% 6% 22% 46%
Dec 2003 4 14% 20% 25% 18% 24%
Jan 2004 5 17% 8% 13% 22% 41%
Feb 2004 6 18% 46% 9% 6% 20%
Mar 2004 7 12% 28% 20% 7% 33%
Apr 2004 8 33% 16% 14% 15% 21%
May 2004 9 23% 16% 17% 17% 26%
Jun 2004 10 17% 19% 16% 26% 23%
Jul 2004 11 18% 28% 20% 15% 20%