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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 April 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
May 2004 0 43% 16% 41%
Jun 2004 1 93% 4% 2%
Jul 2004 2 97% 3% 0%
Aug 2004 3 98% 2% 0%
Sep 2004 4 94% 6% 0%
Oct 2004 5 64% 17% 19%
Nov 2004 6 79% 21% 0%
Dec 2004 7 91% 8% 1%
Jan 2005 8 35% 55% 10%
Feb 2005 9 41% 48% 11%
Mar 2005 10 25% 60% 16%
Apr 2005 11 18% 61% 22%


NINO3
Month lead-time cold neutral hot
May 2004 0 57% 11% 32%
Jun 2004 1 57% 24% 19%
Jul 2004 2 57% 12% 31%
Aug 2004 3 58% 7% 35%
Sep 2004 4 70% 20% 10%
Oct 2004 5 62% 21% 16%
Nov 2004 6 72% 14% 14%
Dec 2004 7 67% 29% 3%
Jan 2005 8 42% 32% 26%
Feb 2005 9 16% 54% 30%
Mar 2005 10 60% 23% 17%
Apr 2005 11 37% 40% 23%


NINO3.4
Month lead-time cold neutral hot
May 2004 0 40% 52% 8%
Jun 2004 1 86% 14% 0%
Jul 2004 2 73% 26% 1%
Aug 2004 3 81% 19% 1%
Sep 2004 4 78% 21% 1%
Oct 2004 5 71% 25% 4%
Nov 2004 6 69% 28% 3%
Dec 2004 7 66% 32% 2%
Jan 2005 8 57% 38% 6%
Feb 2005 9 42% 53% 6%
Mar 2005 10 56% 42% 2%
Apr 2005 11 43% 48% 9%


NINO4
Month lead-time cold neutral hot
May 2004 0 42% 54% 3%
Jun 2004 1 61% 36% 4%
Jul 2004 2 73% 27% 0%
Aug 2004 3 77% 22% 1%
Sep 2004 4 78% 21% 1%
Oct 2004 5 73% 24% 3%
Nov 2004 6 68% 31% 2%
Dec 2004 7 66% 34% 1%
Jan 2005 8 62% 36% 2%
Feb 2005 9 40% 51% 9%
Mar 2005 10 42% 52% 6%
Apr 2005 11 42% 51% 6%