OUR dams are full, the lambs are fat and the sprinklers are running again. But weather experts are warning Australia’s east coast to brace for a return to dry conditions, perhaps even drought, as another El Nino event looms.
After two consecutive years of record rainfall and devastating floods brought on by La Nina, the Bureau of Meteorology warned yesterday that climate indicators show a shift towards drier weather patterns, and a potential swing to the opposite phenomenon, El Nino.
Warmer waters in the Pacific Ocean can trigger an El Nino, which brings less rainfall and drought such as the one that drained Warragamba dam to one-third of its capacity five years ago. Cooler waters bring on La Nina and associated wetter conditions, including those that spurred this year’s floods across NSW, and the devastating Brisbane floods the previous summer.
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A full moon rises over Clovelly as an El Nino weather pattern begins to dominate the forecast.3rd July 2012Photo: Wolter Peeters
Surface tension … waves wash onto Clovelly Beach last night under a full moon. Temperatures have been rising in the Pacific Ocean for the past few months, suggesting a return to El Nino and less rainfall. Photo: Wolter Peeters
A bureau climatologist, Acacia Pepler, said conditions along the equator were yet to reach El Nino thresholds, but most climate models were predicting the event would develop in late winter and early spring.
”The chances of us reaching El Nino are growing,” Ms Pepler said. ”It’s not certain yet, but probability is increasing as the weeks pass.”
But the Weather Channel, which measures the event using different indices, called the result early, declaring yesterday that El Nino had returned.
Drought lingered on the Big Island through another dry winter and is returning this summer to more deeply ravaged, already water-stressed places. These next five months aren’t expected to bring any real reprieve, especially for leeward areas, said Kevin Kodama, senior hydrologist for the National Weather Service.
Weather officials are predicting persistence and possible worsening of drought on the Big Island. Most of the island’s leeward sites had less than 50 percent of normal rainfall during the wet season, which typically runs October through April. Some areas that had slight improvement because of rain earlier this year are already intensifying again and not expecting to get better soon.
On the other hand, most of Big Island’s windward areas had 80 to 110 percent of the normal rainfall range during the wet season, which was ranked the 18th wettest season out of the last 30 years. In fact, the gauge at Hilo Airport received 79.65 inches.
The only exception to the latest prediction is the upland coffee belt, particularly in South Kona, which is unique in that more rainfall is typically observed in the summer than in winter, Kodama said. One theory for this is the onshore sea breeze is more persistent, ascending the mountain slopes, to interact with descending trade winds through the saddle, producing local showers usually in the late afternoon. Meanwhile, the rest of the Hawaiian Island chain generally experiences a dry season, running from now through September.
La Niña conditions, which typically last about nine to 12 months, were primarily to blame for the drier than normal wet season. La Niña is defined as cooler than normal sea-surface temperatures in the central and eastern tropical Pacific Ocean that impact global weather patterns.
THE news from this Midwestern farm is not good. The past four years of heavy rains and flash flooding here in southern Minnesota have left me worried about the future of agriculture in America’s grain belt. For some time computer models of climate change have been predicting just these kinds of weather patterns, but seeing them unfold on our farm has been harrowing nonetheless.
My family and I produce vegetables, hay and grain on 250 acres in one of the richest agricultural areas in the world. While our farm is not large by modern standards, its roots are deep in this region; my great-grandfather homesteaded about 80 miles from here in the late 1800s.
He passed on a keen sensitivity to climate. His memoirs, self-published in the wake of the Dust Bowl of the 1930s, describe tornadoes, droughts and other extreme weather. But even he would be surprised by the erratic weather we have experienced in the last decade.
In August 2007, a series of storms produced a breathtaking 23 inches of rain in 36 hours. The flooding that followed essentially erased our farm from the map.