IRI Home

Home | Climate Info System -> IRI Forecasts -> SPEF forecasts



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 August 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
Sep 2003 0 1% 11% 88%
Oct 2003 1 1% 30% 69%
Nov 2003 2 4% 20% 76%
Dec 2003 3 28% 20% 52%
Jan 2004 4 27% 31% 41%
Feb 2004 5 56% 32% 13%
Mar 2004 6 88% 7% 5%
Apr 2004 7 50% 28% 22%
May 2004 8 97% 1% 1%
Jun 2004 9 91% 7% 2%
Jul 2004 10 75% 22% 3%
Aug 2004 11 72% 19% 10%


NINO3
Month lead-time cold neutral hot
Sep 2003 0 21% 38% 41%
Oct 2003 1 34% 15% 51%
Nov 2003 2 1% 49% 50%
Dec 2003 3 16% 37% 47%
Jan 2004 4 27% 30% 42%
Feb 2004 5 6% 45% 50%
Mar 2004 6 7% 69% 24%
Apr 2004 7 29% 43% 28%
May 2004 8 47% 42% 11%
Jun 2004 9 57% 29% 15%
Jul 2004 10 47% 39% 14%
Aug 2004 11 51% 37% 12%


NINO3.4
Month lead-time cold neutral hot
Sep 2003 0 17% 32% 51%
Oct 2003 1 29% 32% 39%
Nov 2003 2 35% 16% 49%
Dec 2003 3 29% 7% 64%
Jan 2004 4 28% 15% 57%
Feb 2004 5 43% 41% 16%
Mar 2004 6 29% 24% 47%
Apr 2004 7 38% 38% 25%
May 2004 8 9% 58% 34%
Jun 2004 9 6% 59% 35%
Jul 2004 10 57% 30% 13%
Aug 2004 11 39% 37% 24%


NINO4
Month lead-time cold neutral hot
Sep 2003 0 29% 52% 19%
Oct 2003 1 25% 46% 28%
Nov 2003 2 28% 32% 40%
Dec 2003 3 25% 54% 22%
Jan 2004 4 24% 59% 18%
Feb 2004 5 26% 45% 29%
Mar 2004 6 67% 17% 17%
Apr 2004 7 54% 12% 34%
May 2004 8 54% 18% 28%
Jun 2004 9 15% 46% 38%
Jul 2004 10 14% 37% 49%
Aug 2004 11 11% 32% 57%