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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 May 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
Jun 2004 0 31% 63% 6%
Jul 2004 1 25% 62% 13%
Aug 2004 2 23% 63% 14%
Sep 2004 3 44% 43% 13%
Oct 2004 4 40% 49% 10%
Nov 2004 5 24% 69% 7%
Dec 2004 6 38% 50% 12%
Jan 2005 7 39% 47% 14%
Feb 2005 8 33% 49% 19%
Mar 2005 9 26% 56% 19%
Apr 2005 10 19% 60% 21%
May 2005 11 25% 49% 26%


NINO3
Month lead-time cold neutral hot
Jun 2004 0 62% 37% 1%
Jul 2004 1 45% 39% 16%
Aug 2004 2 44% 45% 12%
Sep 2004 3 56% 35% 9%
Oct 2004 4 49% 36% 15%
Nov 2004 5 57% 36% 6%
Dec 2004 6 64% 31% 4%
Jan 2005 7 46% 43% 11%
Feb 2005 8 40% 49% 11%
Mar 2005 9 54% 36% 11%
Apr 2005 10 36% 41% 23%
May 2005 11 21% 51% 27%


NINO3.4
Month lead-time cold neutral hot
Jun 2004 0 44% 38% 18%
Jul 2004 1 65% 33% 2%
Aug 2004 2 59% 37% 4%
Sep 2004 3 54% 42% 5%
Oct 2004 4 55% 38% 7%
Nov 2004 5 64% 31% 5%
Dec 2004 6 46% 48% 6%
Jan 2005 7 36% 51% 12%
Feb 2005 8 29% 39% 31%
Mar 2005 9 39% 46% 15%
Apr 2005 10 30% 54% 16%
May 2005 11 34% 50% 17%


NINO4
Month lead-time cold neutral hot
Jun 2004 0 45% 28% 27%
Jul 2004 1 50% 41% 9%
Aug 2004 2 36% 56% 8%
Sep 2004 3 75% 23% 1%
Oct 2004 4 66% 29% 5%
Nov 2004 5 71% 25% 4%
Dec 2004 6 43% 48% 9%
Jan 2005 7 35% 51% 15%
Feb 2005 8 38% 34% 28%
Mar 2005 9 42% 36% 22%
Apr 2005 10 68% 29% 2%
May 2005 11 28% 56% 16%