Skewness analyses of cumulative rainfall and mean temperature for December-January-February periods during which eastern Pacific SST anomalies were in the highest (warmest) 17% of the period 1895-1997. Shaded climate divisions indicate areas that experienced a significant incidence of above or below median seasonal climate. Confidence levels for skewness can be found under the Above Median colorscale legend. Where climate divisions are annotated, significant skewness in the highest or lowest 25% of the historical distribution was found, with (n/m) indicating n seasons in the first 25%, m seasons in the fourth 25%.

      The precipitation analysis above shows a significant tendency to above median and 4th quartile DJF precipitation over Texas, Oklahoma, Kansas, and Nebraska. Similar seasonal effects are found in the in the September-October-November (SON) , October-November-December (OND), November-December-January (NDJ), and January-February-March (JFM), precipitation analyses. A highly significant shift to below median rainfall conditions is evident over climate divisions in eastern Montana & Wyoming. A less significant shift to dryness - but still significant at better than a 90% confidence level - is found over North Dakota climate divisions. Indications of a tendency to below median rainfall are also evident in the western portion of Ohio River Valley. In the DJF temperature analysis extensive evidence of shifts to above median and 4th quartile seasonal temperatures is found over the Northern Plains, and to below median seasonal temperatures over Louisiana and the Texas gulf coast.