Pineapple Express may deliver sloppy winter, forecasters say | NevadaAppeal.com

Pineapple Express may deliver sloppy winter, forecasters say

Amanda Fehd
Nevada Appeal News Service

This winter is going to be very different from last winter, weather forecasters say.

Meteorologists with the National Weather Service in Sacramento say with no signs of El Niño or La Niña, Sierra residents are twice as likely to see a series of warm storms called the Pineapple Express, interspersed with 45-day droughts.

A Pineapple Express storm picks up loads of moisture in the Indian Ocean and Hawaii, heads toward Alaska where the vapor turns to water and then comes south, dumping its load on the Western United States.

“A Pineapple Express could be one giant dump,” said forecaster John Juskie, “or it could be a series of impulses.”

Either way, it’s bad news for snow lovers.

“It’s warmer; it’s Sierra cement. It’s not good snow,” Juskie said.

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A notorious series of Pineapple Express storms hit California in December 1996 and January 1997, when more than 10 inches of rain melted several feet of fresh snowfall. The resulting snowmelt flooded Carson Valley, washed out Highway 395 near Coleville, closed the highway in Carson Valley and Washoe Valley, isolated Lake Tahoe and inundated Reno.

Meteorologists have learned fluctuating ocean temperatures have a lot to do with why weather varies from winter to winter.

This year, Pacific Ocean temperatures are average, meaning there will likely be no El Niño or La Niña effect on California’s weather.

El Niño happens when the Pacific Ocean is unusually warm, while La Niña happens when temperatures are unusually cold. El Niño often brings more cold storms to the Sierra Nevada, meaning more fun for snow lovers. Last year, a slight El Niño existed.

This year, the Atlantic Ocean is the hottest it’s been in 100 years, rivaling only one year in the 60s. When the Atlantic is warm, meteorologists have noticed a high-pressure ridge builds over the Western United States, from Colorado to California.

That ridge acts like a barrier to Pacific storms, pushing them out of the area toward the Pacific Northwest. That’s why meteorologists expect 45-day droughts.

But the ridge is not strong enough to repel Pineapple Express storms, which have a reputation for pummeling the region in warm rain.

“We can get a two-week predictor on the first big Pineapple Express,” Juskie said. “Once that happens, they tend to happen once every 45 days.”