Explaining La Niña, the driving force behind our winter forecast


FORT WAYNE, Ind. (WANE) — As the temperatures get colder and winter approaches, our weather pattern will be impacted by a phenomenon in the Pacific Ocean. It is called La Niña, and it is the result of trade winds at the equator.

Traditionally near the equator trade winds blow east to west and move warm water that’s near the surface towards Asia. However, in certain years those winds are stronger than usual and cause colder water from the deep to rise to the surface. This makes the water in the Pacific Ocean near the equator a few degrees colder than it usually is. Even this small change in the ocean’s temperature can affect weather all over the world.

Rain usually forms over warm ocean water, meaning Australia and Indonesia may see more rain than usual. While those areas where the cooler water sits have sinking air, resulting in drier conditions. This also impacts the jet stream which controls weather patterns.

During a La Niña year, the jet stream will rise further north than usual and the strength of La Niña will impact how far north it reaches.

Traditional setup and results of a La Niña winter

Traditionally a La Niña winter Brings colder and wetter conditions to the Pacific Northwest, and dry and warm conditions to the southern U-S. Here in the Great Lake Region, the jet stream flows right over us which would favor a wetter winter season.

National Oceanic and Atmospheric Administration (NOAA) looks at this setup in the Pacific to help guide their winter outlook. You can find that breakdown here.

While that outlook is for the entire country, the Live Doppler 15 Fury Weather Team is currently looking over data from past La Niña events and comparing them to past winters in Fort Wayne. This will help us give a more localized forecast for the winter season. Be on the lookout for that local Winter Outlook coming next month.

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