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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 January 2003 observed sea-surface temperatures, and with version 3.05 of the SPEP (Statistical Probabilistic ENSO Predictions) model.
NINO1&2
Month lead-time cold neutral hot
Feb 2003 0 8% 70% 22%
Mar 2003 1 37% 49% 14%
Apr 2003 2 43% 44% 14%
May 2003 3 38% 49% 13%
Jun 2003 4 50% 36% 14%
Jul 2003 5 49% 33% 18%
Aug 2003 6 58% 27% 15%
Sep 2003 7 56% 33% 11%
Oct 2003 8 58% 30% 12%
Nov 2003 9 60% 21% 19%
Dec 2003 10 63% 25% 12%
Jan 2004 11 44% 35% 21%


NINO3
Month lead-time cold neutral hot
Feb 2003 0 1% 28% 71%
Mar 2003 1 5% 51% 44%
Apr 2003 2 8% 48% 44%
May 2003 3 32% 30% 38%
Jun 2003 4 26% 43% 31%
Jul 2003 5 23% 44% 33%
Aug 2003 6 28% 40% 32%
Sep 2003 7 33% 38% 29%
Oct 2003 8 39% 34% 27%
Nov 2003 9 36% 38% 26%
Dec 2003 10 31% 45% 24%
Jan 2004 11 25% 48% 27%


NINO3.4
Month lead-time cold neutral hot
Feb 2003 0 0% 35% 65%
Mar 2003 1 5% 47% 48%
Apr 2003 2 14% 44% 42%
May 2003 3 15% 49% 36%
Jun 2003 4 26% 45% 29%
Jul 2003 5 37% 42% 22%
Aug 2003 6 39% 43% 18%
Sep 2003 7 43% 42% 15%
Oct 2003 8 37% 46% 17%
Nov 2003 9 36% 50% 14%
Dec 2003 10 33% 50% 18%
Jan 2004 11 36% 46% 17%


NINO4
Month lead-time cold neutral hot
Feb 2003 0 1% 51% 48%
Mar 2003 1 2% 47% 51%
Apr 2003 2 3% 50% 47%
May 2003 3 2% 44% 53%
Jun 2003 4 16% 51% 34%
Jul 2003 5 10% 53% 37%
Aug 2003 6 28% 54% 19%
Sep 2003 7 32% 41% 27%
Oct 2003 8 29% 45% 26%
Nov 2003 9 28% 42% 30%
Dec 2003 10 36% 43% 21%
Jan 2004 11 42% 36% 22%