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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 February 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
Mar 2003 0 10% 7% 9% 45% 29%
Apr 2003 1 15% 23% 14% 23% 25%
May 2003 2 31% 16% 25% 23% 4%
Jun 2003 3 37% 26% 24% 10% 3%
Jul 2003 4 51% 20% 17% 7% 5%
Aug 2003 5 61% 23% 8% 6% 3%
Sep 2003 6 63% 23% 5% 7% 2%
Oct 2003 7 68% 15% 8% 4% 5%
Nov 2003 8 48% 21% 9% 12% 10%
Dec 2003 9 60% 18% 7% 7% 8%
Jan 2004 10 44% 37% 11% 3% 5%
Feb 2004 11 26% 20% 15% 19% 21%


NINO3
Month lead-time cold cool neutral warm hot
Mar 2003 0 1% 2% 15% 28% 54%
Apr 2003 1 3% 7% 17% 24% 49%
May 2003 2 16% 17% 15% 29% 23%
Jun 2003 3 21% 17% 18% 16% 28%
Jul 2003 4 26% 17% 12% 22% 23%
Aug 2003 5 27% 15% 11% 25% 23%
Sep 2003 6 25% 14% 13% 27% 20%
Oct 2003 7 26% 14% 13% 26% 21%
Nov 2003 8 17% 13% 16% 26% 27%
Dec 2003 9 16% 8% 27% 22% 27%
Jan 2004 10 21% 19% 12% 21% 27%
Feb 2004 11 26% 19% 17% 22% 15%


NINO3.4
Month lead-time cold cool neutral warm hot
Mar 2003 0 0% 2% 11% 26% 61%
Apr 2003 1 0% 5% 16% 33% 45%
May 2003 2 3% 7% 15% 31% 45%
Jun 2003 3 10% 11% 18% 29% 32%
Jul 2003 4 9% 11% 27% 19% 34%
Aug 2003 5 9% 16% 20% 23% 31%
Sep 2003 6 8% 13% 29% 21% 29%
Oct 2003 7 12% 15% 24% 23% 26%
Nov 2003 8 9% 21% 24% 19% 27%
Dec 2003 9 15% 19% 25% 15% 27%
Jan 2004 10 16% 17% 25% 22% 20%
Feb 2004 11 18% 16% 23% 24% 20%


NINO4
Month lead-time cold cool neutral warm hot
Mar 2003 0 0% 4% 19% 31% 46%
Apr 2003 1 1% 14% 9% 29% 47%
May 2003 2 1% 12% 15% 35% 37%
Jun 2003 3 5% 12% 23% 26% 35%
Jul 2003 4 5% 11% 26% 26% 32%
Aug 2003 5 5% 24% 22% 23% 26%
Sep 2003 6 5% 24% 19% 26% 26%
Oct 2003 7 10% 21% 26% 21% 23%
Nov 2003 8 8% 29% 23% 21% 19%
Dec 2003 9 14% 21% 23% 21% 21%
Jan 2004 10 12% 28% 15% 28% 18%
Feb 2004 11 9% 32% 25% 24% 10%