NOAA’s official Winter Outlook for 2011–2012 is unlikely to please many residents of either the still-soggy Missouri River Basin—which experienced historic flooding this past spring and summer—or the parched south-central United States, where severe to exceptional drought has been in place since spring.
Following a brief interlude of “neutral” sea surface temperature conditions this summer, La Niña has returned to the tropical Pacific Ocean. The cool phase of the El Niño-Southern Oscillation climate pattern is expected to persist through winter.
In the semi-arid Horn of Africa, rain comes in two seasons: the “short rains” of October-December and the “long rains” of March-June. In late 2010 and early 2011, both rainy seasons brought scant rain to the region, which led devastating drought across several countries in 2011. In Somalia, the drought escalated to famine.
In the Arctic, an ocean is surrounded by continents, while Antarctica is continent surrounded by oceans. These differences in the arrangement of land and water contribute to differences in each polar region’s climate, oceanic and atmospheric circulation patterns, and seasonal and long-term sea ice patterns.