The fall, winter and spring of late 2010 and 2011 were characterized by a moderate to strong La Niña across the tropical Pacific Ocean, which shaped CPC’s seasonal outlooks for those seasons.

     Problems: 

i)    Precipitation forecasts for September – November 2010 through April – June 2011 scored at least 30% better than a climatological forecast, the longest streak (eight) of successful forecasts since CPC began issuing seasonal forecasts in 1995.

ii) In contrast, the temperature forecasts during the heart of the winter (November – January, December – February, and January – March) were not as successful, with Heidke skill scores near or below zero. What caused the disparity in skill between the temperature and precipitation forecasts? The answer could be the seasonally dependent influence of unpredictable factors, i.e. AO, PNA et al.