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Despite Quiet Start, Super El Nino Is Coming

(CN) - The impact of this winter's El Nino should be one of the most severe in recorded history, with significant rain and snowfall expected to cause disruptions for residents along the West Coast.

Severe weather conditions produced by El Nino have affected Washington, Oregon and parts of California so far, and should continue to intensify over the coming months.

"The sea surface temperature in the Pacific has already reached 2 degrees Celsius above normal, which is the critical value announcing a Super El Nino," Dr. David Halpern said in a phone interview.

Halpern, who is a senior research scientist at NASA's Jet Propulsion Laboratory, explained that the three-month average sea surface temperatures in the eastern Pacific Ocean along the equator reached 2.1 C and 2.3 C above average for several months during the two previous record-setting winters of 1997-98 and 1982-83, respectively.

"The consensus opinion of many scientific predictions suggests that the 2015-16 El Nino event may be the largest in recorded history," Halpern said.

Dr. Mike Halpert, the deputy director of the National Oceanic and Atmospheric Administration's Climate Prediction Center, explained that it is too early to determine whether this year's El Nino season will exceed or fall short of the strength reached in the previous record years.

"No question that it will be amongst the strongest ones we've seen since 1950. Whether it ends up as one, two or three we won't know for a few more months," Halpert explained.

The warming of the Pacific Ocean off the coast of Ecuador and Peru leads to El Nino effects that impact weather patterns across the globe, and has been measured for over 100 years.

"El Nino is a warming of the uppermost 100 meters of the (Pacific) ocean, which is represented by an increase in sea-surface temperature. Professor Jacob Bjerknes at UCLA, he said it was more than just a warming of waters off of Peru," Halpern said. "If it was just a warming up of Peru it would not affect global weather."

Bjerknes founded UCLA's department of meteorology and in 1969 helped scientists better understand the El Nino phenomenon by suggesting that an anomalously warm spot in the eastern Pacific can weaken the east-west temperature difference, disrupting trade winds which push warm water to the west.

Despite the expectation that this year's El Nino will be one of the strongest in the past 70 years, much of California has not experienced unusual weather patterns so far. But this should change as time goes on, Halpert said.

"It's not what we would have expected at this point with an El Nino. But the reality is that the El Nino pattern and the signal we see for precipitation is much stronger in the January to March period, especially with shifting everything to the south," Halpert said.

Increased rainfall would help California, which has seen its water supplies decimated by a four-year drought. However, experts caution that a stronger rainy season would only provide temporary relief.

"Things will improve as you get more rains, but it won't eradicate the drought, that's for sure," Halpert said.

Dr. Yochanan Kushnir, director of the Cooperative Institute for Climate Applications and Research, agreed that more significant rain would provide temporarily relief, but would not end California's drought.

"This by itself will not immediately erase the damages associated with overdrawing underground water aquifers, or drawing down reservoirs," Kushnir said. "California's water reservoirs are relatively small and so excess rainfall cannot be fully captured and stored."

Besides temperature rises in the Pacific Ocean, El Nino also has an atmospheric component which is important for predicting impacts across North America. Halpern argues that more effort should be put into measuring the interaction between sea temperatures and the atmosphere.

"This is a challenging activity because all El Nino events are different e.g., the location of the high sea-surface temperatures in the central and eastern equatorial Pacific appears to be different in each El Nino," Halpern said.

California had minimal rainfall the past two winters due to a high-pressure pattern in the Pacific Ocean which pushed storms up toward Canada and Washington. Scientists have termed this pattern the "resilient ridge."

"This resilient ridge was also behind the very cold winters we had in the eastern half of the country as it pushed cold arctic air into the Midwest," Kushnir said. "The strong El Nino that developed this summer is so far revising the situation in the North Pacific."

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