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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 April 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
May 2003 0 41% 2% 10% 24% 9%
Jun 2003 1 32% 16% 29% 3% 5%
Jul 2003 2 84% 1% 0% 0% 0%
Aug 2003 3 83% 1% 2% 0% 0%
Sep 2003 4 70% 14% 1% 0% 0%
Oct 2003 5 75% 9% 2% 0% 0%
Nov 2003 6 39% 44% 2% 0% 0%
Dec 2003 7 70% 12% 2% 1% 1%
Jan 2004 8 21% 38% 23% 2% 2%
Feb 2004 9 27% 20% 8% 26% 4%
Mar 2004 10 21% 17% 23% 17% 8%
Apr 2004 11 11% 15% 26% 25% 9%


NINO3
Month lead-time cold cool neutral warm hot
May 2003 0 35% 11% 21% 10% 10%
Jun 2003 1 56% 3% 2% 8% 16%
Jul 2003 2 64% 5% 6% 1% 9%
Aug 2003 3 62% 1% 3% 3% 16%
Sep 2003 4 56% 4% 2% 1% 23%
Oct 2003 5 51% 7% 5% 3% 21%
Nov 2003 6 55% 8% 4% 4% 15%
Dec 2003 7 50% 6% 9% 4% 17%
Jan 2004 8 38% 20% 6% 6% 15%
Feb 2004 9 29% 21% 11% 10% 15%
Mar 2004 10 50% 6% 8% 6% 15%
Apr 2004 11 22% 37% 5% 14% 8%


NINO3.4
Month lead-time cold cool neutral warm hot
May 2003 0 56% 17% 12% 0% 0%
Jun 2003 1 65% 16% 2% 3% 0%
Jul 2003 2 59% 18% 7% 1% 1%
Aug 2003 3 59% 20% 2% 5% 0%
Sep 2003 4 62% 10% 12% 1% 1%
Oct 2003 5 50% 17% 10% 6% 4%
Nov 2003 6 63% 7% 10% 5% 1%
Dec 2003 7 56% 22% 13% 9% 1%
Jan 2004 8 50% 25% 14% 8% 3%
Feb 2004 9 35% 33% 20% 10% 2%
Mar 2004 10 46% 29% 13% 11% 1%
Apr 2004 11 31% 28% 27% 11% 3%


NINO4
Month lead-time cold cool neutral warm hot
May 2003 0 39% 13% 24% 19% 4%
Jun 2003 1 42% 12% 22% 15% 9%
Jul 2003 2 68% 18% 12% 1% 0%
Aug 2003 3 72% 20% 6% 1% 0%
Sep 2003 4 74% 17% 6% 3% 1%
Oct 2003 5 55% 32% 7% 5% 1%
Nov 2003 6 69% 21% 7% 2% 1%
Dec 2003 7 29% 25% 35% 8% 2%
Jan 2004 8 38% 30% 12% 17% 3%
Feb 2004 9 28% 31% 22% 10% 9%
Mar 2004 10 28% 27% 32% 7% 6%
Apr 2004 11 35% 9% 41% 7% 9%