What is in this article?:
- Oceans combine to change U.S. weather patterns
- Should improve farming conditions/
• Several factors contribute to changing weather patterns.
• La Niña events result in Texas drought.
• Adaptability is key for agriculture success.
RAINBOWS may be more common in the Southwest with the onset of an El Niño, which is expected to bring colder, wetter conditions this winter. The longer El Niño stays around, the wetter it will be, says historical climatologist Evelyn Browning Garriss.
A combination of warming water temperatures in the Atlantic and changes in the Pacific Decadal Oscillation (PDO) pattern (which shifts heat and energy to different parts of the world) is creating more extreme weather patterns and affecting food production.
In the Southwest, those changing patterns may mean extreme weather for the next 20 years and could mimic Texas weather of the 1950s.
In the near-term, however, an El Niño event likely will bring colder temperatures and more moisture into the Southwest. “The longer an El Niño remains, the wetter it will be,” says Evelyn Browning Garriss, historical climatologist.
Garriss, speaking at the recent Beef Financial Management Conference in Amarillo, said this past summer’s unusual weather was shaped by unusual conditions, including eruption of two volcanoes — one in Russia and one in Iceland — as well as warming waters in the Atlantic, Pacific and Indian Oceans. Also, prevailing winds carried heat into key production areas of the Northern Hemisphere.
“We just broke nearly 2,000 heat records this summer,” she said. Lack of rain was not as big a factor as the heat, which increased evapotranspiration significantly. “The water supply couldn’t keep up. We had flash drought over 77 percent of the country.”
Garriss said the Atlantic Ocean controls Midwest weather. The Atlantic also features an oscillation factor — The Atlantic Multidecadal Oscillation (AMO). “When the Atlantic is hot, the corn fries.”
The two volcanoes also caused problems. “Eruptions altered the stratosphere and air pressure. Air pressure controls wind.” Volcanoes “trapped Arctic air well north. Fairbanks, Alaska., had 27 feet of snow; we had a warm winter.”
Garriss said that unusual occurrence — two volcanic eruptions in a year — is “very odd, a one-, two- or three- century occurrence. We don’t expect a repeat this winter.”
When a volcano erupts it shoots debris into the air. If it shoots high enough, debris goes into the stratosphere. “When it’s quiet, debris may remain there up to seven years and water collects and creates particles.”At some point, those particles create clouds, which block sunlight and affect weather patterns.
The Pacific climate also causes significant weather changes. “We had a cold La Niña for two years,” Garriss said. “It was a relatively small La Niña. But the colder water changed air pressure. La Niña equals a Texas drought.”
El Niño developed quickly. “Conditions developed for an El Niño five months after La Niña finished,” she said. “It usually takes two years.”
An El Niño also affects tropical storms. “It drives tropical moisture away from the Western Gulf. El Niño kept Hurricane Isaac weaker. Isaac carried a lot of moisture into the Midwest, too late for corn, but it helped soybeans and provided moisture for winter wheat planting.” Without El Niño, Isaac could have developed into a much stronger storm.