PHOENIX — Forecasters are expecting a warmer and drier winter in Arizona as the La Nina weather pattern moves into place.
La Nina typically leads to a warm, dry winter in the southwestern United States, including Arizona, according to Mark O’Malley with the National Weather Service in Phoenix.
The weather pattern is triggered by colder temperatures in the Pacific Ocean, which influences the position of the Pacific jet stream, according to the National Oceanic and Atmospheric Administration.
Scientists at the NOAA declared the arrival of La Nina on Thursday, however O’Malley said this year’s La Nina is weaker than normal.
“The reflection in the atmosphere may not be as strong but the odds are slightly tilted toward a warmer and drier winter for Arizona,” he said.
Last winter, El Nino — caused by warmer Pacific Ocean temperatures — was expected to turn Arizona into Seattle. Instead, it produced one of the driest winters on record.
O’Malley said there is a chance that this year’s La Nina may produce more precipitation than last winter.
“There is a chance, and it’s not a small chance, that we could still have an average or wetter winter this year,” he said.
Snowfall in the northern part of the state is important, according to O’Malley, because reservoirs are filled after mountain snow melts, which would help prevent drought.
While most of the Southwest should stay dry, O’Malley also said the Pacific Northwest is more likely to have a cooler, wetter winter.
According to the NOAA, the most recent winter with a La Nina was the winter of 2011-12.
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