El Nino officially arrives — with warning – Hawaii Tribune-Herald

As El Nino officially takes hold in the Pacific, the National Weather Service Thursday warned there’s a likely chance it could rank “among the largest El Nino events in the historical record going back to 1950.”

El Nino cycles, characterized by above-average sea surface temperatures in the central and eastern equatorial Pacific Ocean and weak tradewinds, can cause changes in global weather patterns. In Hawaii, the cycle has been linked to more hurricane activity in the Central Pacific Basin in the summer and drought in the winter, which can lead to wildfire threats.

According to the latest update, published Thursday by NWS’s Climate Prediction Center, El Nino conditions developed over the last month with ocean surface temperatures ranging between .7 and 2.1 degrees Celsius, or 1.26 to 3.78 degrees Fahrenheit, above normal. Wind anomalies were also present in the central equatorial Pacific, which further fueled the cycle’s development.

A “very strong” El Nino — what some climatologists have dubbed a “super El Nino” — has a 63% chance of occurring between November and January, right at the end of Hawaii’s hurricane season. Hurricane season started June 1 and lasts through November.

Latest forecasts estimate for this season that there’s a 70% chance the Central Pacific Basin will see five to 13 tropical cyclones, which include tropical depressions, tropical storms and hurricanes.

National Weather Service meteorologist Derek Wroe said the El Nino cycle could mean the region sees a number of cyclones “on the higher range of that spectrum” with possibly more storms at the end of the season when the cycle is expected to be the strongest. He added that exact forecasts and conditions are still uncertain.

“We tend to have more tropical cyclone activity in El Nino years,” he said. “Very strong events bring those odds even higher.”

He reiterated that stronger El Nino cycles do not necessarily mean the weather events, like hurricanes, will be stronger, but rather that they are more likely to occur.

The latest El Nino forecast shows the majority of Hawaii’s hurricane season will likely be defined by moderate to strong El Nino conditions, with very strong conditions becoming more likely beginning in September.

Very strong El Nino seasons occur when sea surface temperatures rise above 2 degrees Celsius, or 3.6 degrees Fahrenheit.

Between now and August, El Nino conditions have a 32% chance of being weak and 58% of being moderate. That changes swiftly in the three month span from July through September, with a weak El Nino at 11%, moderate at 46%, strong at 36%, and very strong at 6%.

The odds shift from September through November, with the likelihood of a very strong El Nino jumping to 48%, and moderate decreases to 36%. Then, in the three month periods preceding both December and January, the likelihood for a very strong El Nino increase to 62% and 63% respectively.

Wroe said Hawaii residents can expect a slightly wetter summer — though it will still be fairly dry.

During winter, the island’s usual wet season, a strong El Nino could cause drought conditions and possibly bring wildfire risk, especially during the following summer.

He added that the high probability of very strong El Nino conditions is unique.

“Right now there’s a 63% chance that it could be a very strong El Nino,” he said. “A 63% chance of forecasting something — that doesn’t happen very often. That’s a very high probability.”