What La Nina could mean for Georgia this winter

By: Brian Monahan

Updated:

GEORGIA - We're finally starting to see cooler temperatures after a warm start to fall, so what does that mean for your winter??

The winter outlook will be released on Thursday.

One of the biggest factors in the forecast has to do with ocean water temperatures more than 2,000 miles away from north Georgia in the Pacific Ocean.

Severe Weather Team 2 Meteorologist Brian Monahan says the Pacific Ocean plays a big role in the weather in the eastern half and actually the entire United States.

This year, Pacific ocean water temperatures along the equator are crashing. That's a clear signal of a dawning La Nina event. 

Stronger than normal winds cause upwelling, bringing cooler water from deep down below to the ocean's surface.


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On Tuesday, Monahan spoke with Keith Stellman, the meteorologist-in-charge at Atlanta's local National Weather Service office. Stellman said La Nina is a big disruption to the normal winter time patterns in the United States.

"When you get a large pool of cool water over a basin the size of the Pacific. in the case of La Nina, you get high pressure and low pressure to develop in certain areas and want to just stay in that area. That has an impact on the jet stream."

In a La Nina winter, the polar branch of the jet stream generally stays farther to the north, keeping the northern part of the country cold. But in the southeast, we stay warmer than average.

Precipitation, usually below average in a La Nina winter for us but there can be exceptions. 

In fact, Stellman told Monahan some research shows that wedge ice events like one that hit Atlanta in 2015 are more likely during La Ninas.

"The pattern, the way that it sets up with the jet stream, it allows a lot more cold air damming to occur, down the eastern half of the Appalachians, and that is typically when we get our ice here in north Georgia," he said. 

Atlanta averages just under three inches of snow each winter.


 

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