El-Niño means the Pacific Ocean around the equator is warmer than normal.
La-Niña means the Pacific Ocean is cooler than normal.
The cycles happen every 3-5 years. El-Niño lasts 9-12 months, typically, followed by La-Niña which lasts 1-3 years.
There have been El-Niño cycles, which lasted up to 3-4 years before.
These two cycles change the wind direction and air temperatures around the globe.
There’s an irregular cycle of weather patterns in the Pacific Ocean that takes several years to change. The two states it oscillates between are called The Girl and The Boy – La Niña and El Niño.
As an oversimplified overview of the effects, La Niña tends to reinforce the patterns that are already there, dry regions become even dryer, wet regions become even wetter. El Niño partially counteracts this pattern, leading to seemingly unusual weather like a moderate and wet Summer where you would expect a hot and dry one.
El Niño and La Niña are years long Pacific Ocean temperature changes that become most pronounced around Christmas and change the regional weather patterns of north and South America most and global weather patterns generally.
This pattern affected how the Mayans and Incans built cities but was given the name El Niño by the Spanish (the original full name was “El Niño de Navidad”
El Niño is a diminishing of the westerly trade winds in the pacific leading to a much warmer south pacific that leads to increased rain and flooding (this flooding is what drove the building pattern changes of the Maya and Inca).
La Niña is the opposite, a strengthening of the westerly trade winds leading to a cooling of the southern Pacific Ocean due to increased upwelling of cold water from the deep ocean. La Niña leads to dryer winters in the south west and wetter winters in the Pacific Northwest due to the jet stream changes.
From past years we know what to expect for long term forecasts and things like snow fall over the western mountains. It’s useful for long term forecasting and planning but from a day to day over the winter, it will just be “weird” weather for most people.
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