The chances of an El Nino weather pattern developing this year are increasing as tropical cyclones may lead to further warming of the Pacific Ocean, Australia’s Bureau of Meteorology said.
Severe Tropical Cyclone Pam and tropical storm Bavi, which rates as a Category 1 cyclone on Australia’s scale, have straddled the equator and produced one of the strongest reversals in trade winds in recent years, the Melbourne-based bureau said Tuesday. This is expected to increase already warm sub-surface temperatures in the tropical Pacific Ocean, which may in turn raise surface temperatures in the coming months, it said. El Nino can parch Asia and bring rain to South America.
For most of 2014, Australia raised the possibility that an El Nino was on the way for the first time since 2010 before tempering forecasts as changes to the atmosphere failed to develop consistently. The bureau upgraded its outlook to watch on March 3 after the Pacific warmed. A majority of models predict El Nino will develop about mid-year, the World Meteorological Organization said Monday.
“The past fortnight has seen unusual conditions in the tropical Pacific, which may increase the chance of El Nino in 2015,” Australia’s bureau said in a statement. All eight models that were surveyed suggest ocean temperatures will exceed El Nino thresholds by mid-year, it said.
El Ninos, caused by periodic warmings of the equatorial Pacific, can roil world agricultural markets as farmers contend with drought or too much rain. During the event, there is a sustained weakening of the trade winds. It’s too early to say whether the reversal is a short-term fluctuation or the beginning of a sustained trend, according to the bureau.
Model outlooks suggest ocean temperatures will remain warmer-than-average, and possibly in excess of weak El Nino thresholds, into the second quarter of 2015, the World Meteorological Organization said. An El Nino developed last month and it’s probably too weak to have much global impact, the U.S. Climate Prediction Center said March 5.
Australia maintained a watch for El Nino, indicating about a 50 percent chance of the pattern forming in 2015. Model outlooks spanning February to May generally have lower accuracy than predictions made at other times of the year, it said.
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