Defining a Teleconnection

DISCUSSION: A teleconnection is a link between weather patterns and changes occurring in widely separated areas of the globe. You know of at least one but may be unaware that it is a teleconnection. Ever heard of El Niño? Anyway, this is a teleconnection. The full name is El Niño Southern Oscillation. First, the Southern Oscillation will be discussed. This is the pressure difference between eastern and western parts of the Pacific Ocean.

How does this effect the weather? Indirectly. Whether the pressure is higher or lower than normal in one area, it will change the direction of surface winds across the ocean. This causes warm or cool water to move, which in turn will affect the weather. The Southern Oscillation indicates El Niño, La Niña, or in some cases, La Nada.

El Niño, by definition, is an odd warming of surface ocean water temperatures in the eastern tropical Pacific, off the coasts of Ecuador and northern Peru. It is called El Niño because this condition often occurs around Christmas. This can last for quite some time, for weeks, months, or over a year! Some of the effects of the El Niño are as follows. Convection, where water vapor rises and condenses to form clouds, increases over the eastern Pacific. The north to south temperature gradient over the eastern Pacific increases as well. In addition, there are fewer storms and mild temperatures across the north. Storm tracks tend to shift southward across the United States during El Niño. Finally, there is a reduced flow of air from the polar regions.

A La Niña is when sea surface temperatures are cooler than normal in the Pacific because of a strong increase in trade winds. Contrary to El Niño, La Niña causes an absence of convection of the eastern Pacific and sees it shift toward the western Pacific. The temperature gradient mentioned before also diminishes. One of the effects of La Niña has on the United States is that it increases the amount of cold air outbreaks in the North. However, there is variation in temperature and storm activity in the north while the south sees warmer and drier weather.

In conclusion, teleconnections can play a massive role in shaping local weather patterns.

For more on teleconnections, click here!

© 2018 Meteorologist Jennifer Naillon