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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 October 2003 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
Nov 2003 0 6% 10% 83%
Dec 2003 1 7% 8% 85%
Jan 2004 2 30% 8% 62%
Feb 2004 3 65% 14% 21%
Mar 2004 4 95% 4% 1%
Apr 2004 5 88% 11% 1%
May 2004 6 93% 6% 1%
Jun 2004 7 61% 23% 16%
Jul 2004 8 72% 24% 4%
Aug 2004 9 59% 39% 3%
Sep 2004 10 63% 26% 12%
Oct 2004 11 61% 25% 14%


NINO3
Month lead-time cold neutral hot
Nov 2003 0 15% 33% 52%
Dec 2003 1 16% 66% 18%
Jan 2004 2 28% 25% 47%
Feb 2004 3 47% 43% 10%
Mar 2004 4 37% 36% 27%
Apr 2004 5 30% 46% 24%
May 2004 6 64% 29% 6%
Jun 2004 7 22% 54% 24%
Jul 2004 8 20% 57% 23%
Aug 2004 9 24% 58% 19%
Sep 2004 10 22% 29% 48%
Oct 2004 11 19% 57% 24%


NINO3.4
Month lead-time cold neutral hot
Nov 2003 0 29% 44% 27%
Dec 2003 1 29% 61% 10%
Jan 2004 2 32% 47% 21%
Feb 2004 3 64% 27% 10%
Mar 2004 4 10% 69% 21%
Apr 2004 5 27% 52% 21%
May 2004 6 10% 55% 35%
Jun 2004 7 18% 78% 4%
Jul 2004 8 25% 56% 19%
Aug 2004 9 31% 50% 19%
Sep 2004 10 32% 36% 32%
Oct 2004 11 30% 51% 18%


NINO4
Month lead-time cold neutral hot
Nov 2003 0 29% 63% 9%
Dec 2003 1 29% 55% 16%
Jan 2004 2 52% 38% 10%
Feb 2004 3 27% 56% 17%
Mar 2004 4 59% 19% 22%
Apr 2004 5 61% 28% 11%
May 2004 6 65% 23% 13%
Jun 2004 7 69% 19% 12%
Jul 2004 8 46% 44% 10%
Aug 2004 9 8% 75% 18%
Sep 2004 10 17% 51% 32%
Oct 2004 11 30% 43% 27%