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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 September 2004 observed sea-surface temperatures, and with version 4.01 of the SPEP (Statistical Probabilistic ENSO Predictions) model.

NINO1&2
Month lead-time cold neutral hot
Oct 2004 0 6% 36% 58%
Nov 2004 1 2% 32% 66%
Dec 2004 2 11% 38% 50%
Jan 2005 3 58% 22% 19%
Feb 2005 4 29% 40% 31%
Mar 2005 5 28% 49% 23%
Apr 2005 6 94% 3% 3%
May 2005 7 76% 23% 1%
Jun 2005 8 72% 25% 3%
Jul 2005 9 60% 36% 4%
Aug 2005 10 54% 43% 3%
Sep 2005 11 27% 54% 18%


NINO3
Month lead-time cold neutral hot
Oct 2004 0 10% 37% 53%
Nov 2004 1 0% 49% 51%
Dec 2004 2 0% 44% 56%
Jan 2005 3 12% 38% 50%
Feb 2005 4 7% 48% 45%
Mar 2005 5 14% 60% 26%
Apr 2005 6 15% 52% 33%
May 2005 7 13% 50% 37%
Jun 2005 8 22% 52% 26%
Jul 2005 9 26% 58% 16%
Aug 2005 10 25% 59% 16%
Sep 2005 11 12% 75% 13%


NINO3.4
Month lead-time cold neutral hot
Oct 2004 0 28% 15% 56%
Nov 2004 1 14% 23% 62%
Dec 2004 2 28% 4% 68%
Jan 2005 3 16% 23% 61%
Feb 2005 4 10% 11% 79%
Mar 2005 5 4% 49% 47%
Apr 2005 6 8% 52% 40%
May 2005 7 11% 55% 35%
Jun 2005 8 7% 78% 15%
Jul 2005 9 24% 64% 12%
Aug 2005 10 31% 51% 18%
Sep 2005 11 16% 57% 27%


NINO4
Month lead-time cold neutral hot
Oct 2004 0 14% 3% 82%
Nov 2004 1 28% 26% 46%
Dec 2004 2 28% 2% 70%
Jan 2005 3 18% 20% 62%
Feb 2005 4 14% 7% 79%
Mar 2005 5 26% 6% 68%
Apr 2005 6 26% 19% 55%
May 2005 7 2% 33% 65%
Jun 2005 8 3% 49% 49%
Jul 2005 9 5% 74% 21%
Aug 2005 10 13% 52% 35%
Sep 2005 11 9% 68% 23%