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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 June 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
Jul 2003 0 28% 67% 5%
Aug 2003 1 18% 78% 4%
Sep 2003 2 25% 72% 3%
Oct 2003 3 27% 67% 6%
Nov 2003 4 26% 70% 4%
Dec 2003 5 26% 69% 5%
Jan 2004 6 63% 31% 6%
Feb 2004 7 45% 28% 27%
Mar 2004 8 38% 37% 25%
Apr 2004 9 39% 33% 27%
May 2004 10 53% 26% 21%
Jun 2004 11 41% 42% 16%


NINO3
Month lead-time cold neutral hot
Jul 2003 0 62% 23% 15%
Aug 2003 1 41% 57% 3%
Sep 2003 2 30% 65% 5%
Oct 2003 3 27% 67% 5%
Nov 2003 4 22% 74% 4%
Dec 2003 5 35% 59% 6%
Jan 2004 6 43% 48% 9%
Feb 2004 7 36% 51% 13%
Mar 2004 8 50% 39% 12%
Apr 2004 9 56% 28% 17%
May 2004 10 79% 20% 1%
Jun 2004 11 71% 25% 4%


NINO3.4
Month lead-time cold neutral hot
Jul 2003 0 40% 52% 9%
Aug 2003 1 40% 55% 5%
Sep 2003 2 27% 66% 7%
Oct 2003 3 33% 59% 8%
Nov 2003 4 37% 55% 8%
Dec 2003 5 39% 53% 8%
Jan 2004 6 38% 48% 14%
Feb 2004 7 36% 50% 15%
Mar 2004 8 41% 52% 7%
Apr 2004 9 72% 17% 10%
May 2004 10 38% 51% 11%
Jun 2004 11 55% 28% 17%


NINO4
Month lead-time cold neutral hot
Jul 2003 0 33% 54% 13%
Aug 2003 1 33% 63% 4%
Sep 2003 2 23% 64% 13%
Oct 2003 3 35% 58% 7%
Nov 2003 4 39% 56% 5%
Dec 2003 5 43% 52% 5%
Jan 2004 6 33% 58% 9%
Feb 2004 7 35% 55% 11%
Mar 2004 8 35% 57% 8%
Apr 2004 9 41% 54% 4%
May 2004 10 31% 53% 17%
Jun 2004 11 35% 58% 7%