Amid reports of a decline in Lake Victoria's water levels, the time series plot may seem paradoxical. Readily apparent in this plot are huge (> 1σ) positive anomalies experienced during much of the second half of the 20th century in these areas. This apparent 'paradox' clearly demonstrate that other terms in the water budget/cycle (e.g. evaporation and drainage) are equally important, and may have offset the abundant precipitation to result in the reported water-level decline. A continuation of abundant short-rains is implied by the models' projection of a statistically significant upward trend persisting throughout the 21st century.
While weaker than those of the short rains, the time-series plots show a prevalence of wetter anomalies (in MAM) during the latter part of the 20th century. No negative anomalies are evident to support the decline in lake levels during this season either. The models show a continuation of wetter conditions during most of the 21st century, although the signal-to-noise ratio in the model projections for this season's precipitation is comparatively low.
While most of the models simulate an annual cycle similar to that observed in the 20th century, systematic biases are evident. These include a dry (wet) bias during the long- (short-) rains season. There is a remarkably high degree of agreement across the models in projecting an increase in mean monthly precipitation throughout the year. However, the HadGEM1 model show lesser short-rains, while the HadCM3 and CNRM-CM3 give indications for shorter long-rains (less precipitation in May).