The plots show the odds of a wet/dry or warm/cold season with ENSO conditions preceding the season. ENSO conditions are defined from the SOI index. The lead time is 3 seasons to concurrent. Results are based on the US climate division dasaset for 1896-1995. Extreme is defined as being in the highest or lowest 20% of the 100 year record. ENSO is defined as the top 20 SOI years (La Nina) and the lowest 20 SOI years (El Nino). Four extreme events would be expected by chance. A decrease number of years to zero or one year would be significant at the 99.3% and 95.7% level, respectively. An increase to seven, eight or nine years would be significant at the 95.4%, 98.6% and 99.9% levels. Actual significance is probably less due to the number of tests run and time/space correlations in the dataset.

 


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