Tuesday, May 29, 2012

Hawaii’s changing weather and the Pacific Oscillation

The ocean temperature is warming in the central Pacific Ocean and as a result the weather in Hawaii is changing.  

Climatologists have tied droughts and storms in Africa, the Americas, and Australia to changes in ocean surface temperatures in the central Pacific Ocean. The weather cycle is called “La Niña” when the surface water is warmer and “El Niño” when the water is colder. These alternating weather patterns are known as the Pacific Oscillation and though they take months or even years to develop, NOAA is always trying to predict when the changes will happen to prepare people for droughts and floods.

Living in Hawaii, these cycles are not as abstract to us as they used to be on the mainland.  When we jump into the ocean here, we can give a global weather report by the water surface temperatures we experience (we also have a thermometer watch to make it less subjective).

The La Niña cool water weather pattern which has affected Hawaii’s weather since about March 2010 is transitioning to a warm water El Niño.  El Niño weather brings more rain, storms and bigger waves for surfing in Hawaii.  We can already feel the effects of the increased cloudiness, humidity and dark clouds arriving from the warming surface waters.  Combined with heavy volcanic emissions from the volcano, the Kona coast has become hazier with fewer sunny days.

The slow warming of the Pacific Ocean, associated with an El Niño, has already deluged Oahu and Kauai with water from huge rain storms this past winter; Oahu was pummeled with water spouts, thunderstorms with hail, and a tornado. The El Niño may mean the arrival of more cyclones this summer during the most active months of the Central Pacific Hurricane season from July to October. 

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