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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 December 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
Jan 2004 0 2% 12% 86%
Feb 2004 1 33% 22% 46%
Mar 2004 2 88% 10% 2%
Apr 2004 3 87% 12% 1%
May 2004 4 74% 25% 2%
Jun 2004 5 90% 9% 2%
Jul 2004 6 88% 10% 2%
Aug 2004 7 86% 12% 2%
Sep 2004 8 83% 16% 2%
Oct 2004 9 87% 7% 6%
Nov 2004 10 90% 9% 2%
Dec 2004 11 87% 11% 2%


NINO3
Month lead-time cold neutral hot
Jan 2004 0 11% 65% 24%
Feb 2004 1 9% 58% 32%
Mar 2004 2 77% 22% 1%
Apr 2004 3 85% 13% 1%
May 2004 4 81% 18% 2%
Jun 2004 5 57% 42% 1%
Jul 2004 6 70% 23% 7%
Aug 2004 7 66% 24% 10%
Sep 2004 8 60% 38% 2%
Oct 2004 9 22% 41% 37%
Nov 2004 10 55% 33% 12%
Dec 2004 11 16% 40% 44%


NINO3.4
Month lead-time cold neutral hot
Jan 2004 0 29% 43% 28%
Feb 2004 1 16% 62% 22%
Mar 2004 2 17% 71% 13%
Apr 2004 3 25% 53% 23%
May 2004 4 32% 50% 18%
Jun 2004 5 12% 83% 5%
Jul 2004 6 29% 59% 12%
Aug 2004 7 26% 38% 36%
Sep 2004 8 75% 21% 3%
Oct 2004 9 8% 66% 26%
Nov 2004 10 15% 26% 59%
Dec 2004 11 1% 37% 63%


NINO4
Month lead-time cold neutral hot
Jan 2004 0 31% 67% 2%
Feb 2004 1 30% 60% 10%
Mar 2004 2 30% 41% 28%
Apr 2004 3 29% 37% 34%
May 2004 4 71% 16% 13%
Jun 2004 5 32% 39% 29%
Jul 2004 6 49% 18% 33%
Aug 2004 7 6% 26% 68%
Sep 2004 8 57% 18% 25%
Oct 2004 9 48% 14% 39%
Nov 2004 10 10% 64% 27%
Dec 2004 11 15% 68% 18%