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Utah's upcoming winter is likely to feature a repeat appearance by La Niña, a weather phenomenon fueled by colder than average equatorial waters in the Pacific.
But forecasters are betting it won't be as wet and snowy as last winter, when records for rain and snowfall were shattered and waterways flooded throughout the state.
For Utah, La Niña usually means wetter than average winter precipitation in the north and drier than average conditions down south, said Larry Dunn, meteorologist in charge at the Salt Lake City station of the National Weather Service.
"Last year, the entire state ended up being quite wet. That's unusual for La Niña," he said.
Nonetheless, the National Oceanic and Atmospheric Administration (NOAA) reports that the La Niña phenomenon is strengthening again. Although it isn't as strong as it was last year at this time, it could intensify and play a significant role in the coming winter's weather.
NOAA's extended forecast for the Great Basin is in keeping with the typical La Niña pattern, Dunn said: Drier than average in the south and a 50-50 chance of wetter than usual in the north.
"We're not looking for a repeat of last year," Dunn said.
Beyond La Niña, there is a wild card in the works, according to Mike Halpert, deputy director of NOAA's Climate Prediction Center. It's called the Arctic Oscillation, and it's difficult to predict.
The Arctic Oscillation fluctuates between negative and positive phases. The negative phase pushes cold air from Canada into the United States. The Arctic Oscillation can amplify La Niña, Halpert said in a news release. Such episodes, however, usually don't last longer than a few weeks at a time.
Randy Julander, the Utah snow survey supervisor for the National Resources Conservation Service (NRCS), says water managers are going to have to keep a sharp eye on snowpack this winter to know whether water should be released from reservoirs in advance of spring runoff. Reservoirs are full.
Julander puts the odds at about 80 percent that northern Utah will be wetter than normal and similar odds that southern Utah will be drier.
The Snow Survey measures snowpack across Utah's mountains at 108 gauges called "snotel" sites. The agency also evaluates snow depths manually three times each winter at 40 locations. The system helps water managers determine how much volume to release from reservoirs during winter months.
"In the north, it's highly likely that they'll have to let water out of the reservoirs [before spring]," he said. "They have to balance the needs of the water users against the chance for widespread flooding. In a case like last year, it pretty well overwhelmed the [water storage] system in many cases."
In the short term, a quick moving cold front expected to blow into the state late Monday will not bring an end to Utah's beautiful fall weather. Temperatures should rebound under sunny skies beginning Wednesday.