|SOUTHERN OSCILLATION INDEX
METEOROLOGIST JEFF HABY
This is the second essay of the series of commonly analyzed teleconnections. Teleconnections are
weather patterns that help produce long term forecasts (beyond 5 days). Pressure patterns
in the atmosphere tend to promote certain weather patterns. The second teleconnection
we will look at is the Southern Oscillation Index (SOI).
The SOI is based on the sea level pressure difference between Tahiti and Darwin. Sustained
negative values indicate an El Nino pattern. El Nino brings drier weather to Australia (higher pressure) and
warmer sea surface temperatures to coastal Southern America in the Pacific (Peru) (lower pressure).
Sustained positive values indicate a La Nina pattern. La nina brings wetter weather to Australia (lower pressure) and
cooler sea surface temperatures to coastal Southern America in the Pacific (Peru) (higher pressure). This is best
for catching fish off the coast of South America. A La Nina pattern tends to develop more hurricanes in the
Atlantic that move toward the U.S. from Africa.
More information is available at:
Also see the links below for U.S. influences