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Tuesday, October 20, 2015

El Nino could mean wet winter for Arizona

NOAA predicts El Niño will continue through winter

By SAMANTHA WITHERWAX Cronkite News 

PHOENIX – Fresh off another punishing storm, Arizonans likely can expect to see a wet winter as El Niño conditions heat up the Pacific Ocean.

The National Oceanic and Atmospheric Administration said on Monday that El Niño conditions are present and there is a 95% chance they will continue through the winter. The weather patterns are on track to be the strongest since 1997, NOAA said in its winter forecast.

“At this point, we are fairly certain that El Niño will remain on the current trajectory, and we will see one of the top three strongest events on record since 1950,” Ben McMahan, Research, Outreach and Assessment Specialist for Climate Assessment for the Southwest, said in an email following the forecast.

For Arizona, El Niño usually means a cooler, wetter winter. Rising ocean temperatures and the current weather patterns are closely tracking the fall of 1997.

Recent Arizona weather likely can be tied to El Niño, according to McMahan.

“The increased tropical storm activity in the eastern Pacific has pushed a number of storms into the Southwest, and we tend to see more tropical storm activity in the Southwest in El Niño years,” McMahan said. “The tropical storm season is waning, but we might see a few more systems push in this season.”

El Niño events are unpredictable but generally bring above average precipitation to the Southwest, McMahan said.

“Going forward, the forecast does favor wetter-than-average conditions all the way into the spring, with the January – March season the most likely 3-month period to be wetter than average,” Mike Halpert, Deputy Director for the Climate Prediction Center, said in an email.

El Niño is a climate pattern tied to the warming of sea surface temperatures in the equatorial Pacific. It occurs about every two to seven years. Sea surface temperatures across the central and eastern Pacific, and Indian Ocean have been above average in the past four weeks, according to Halpert.

Although precipitation is historically higher than average with a strong El Niño, encountering rain everyday should not be expected.

“In the 1997–1998 event—the strongest El Niño event on record—most of Arizona and New Mexico received above-average precipitation in December but below-normal precipitation for all of January before returning to normal or above-normal precipitation in February and March,” McMahan said.

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