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Strong El Nino could bring winter rains to southeast

Tue, Jul 21, 2015

Climate Change, Water

Florida state climatologist David Zierden.

Florida state climatologist David Zierden.

By BRUCE RITCHIE
FLORIDAENVIRONMENTS.COM

The strong El Nino now underway is expected to bring heavy rains to the southeast in the upcoming winter but some drier weeks until then, Florida state climatologist David Zierden said Tuesday.

El Nino refers to a climate pattern associated with high air pressure in the western Pacific Ocean and low pressure in the eastern Pacific. In the Atlantic Ocean, the pattern also is associated with fewer tropical storms.

During a webinar to discuss drought assessments for the Apalachicola, Chattahoochee and Flint rivers in the southeast, Zierden explained that forecasters believe the current El Nino could become the strongest in recorded history.

“El Nino is coming on like gangbusters,” Zierden said, “and is looking like it’s going to be one of the major event of the century right now.”

He said very warm water is aligned along the equator from the South American coast to the western Pacific Ocean. Water temperatures there are 4 degrees Celsius above normal.

7-14-15 SE drought statusMany row crops along the rivers in Alabama, Florida and Georgia are in a critical period for growth in the next two to three weeks and are in need of water, Zierden said.

But El Nino frequently brings a drier weather patterns. And portions of the basin are drying out — “but nothing too drastic at this time,” he said.

Without rain in the next few weeks, the pressure on farmers to irrigate their crops will increase, Zierden said.

While the region usually can expect five to six inches of rain per month in July, that normally drops to three to five inches in August.

While Southeast Florida is in a severe drought, there is limited drought in Alabama and Georgia and very little in the Florida Panhandle.

In the past, heavy water demand has contributed to upper stretches of the Flint River near Atlanta going dry along with the Spring Creek tributary.

Zierden did not address stream and river flows. Other speakers said groundwater and stream flows were normal with flows declining as usual during the summer.

A decline in the Apalachicola River to below normal flow is slightly favored even without factoring in the El Nino, said Jeff Dobur of the Southeast River Forecast Center at the National Weather Service.

And Zierden noted that NOAA had forecast a 70 percent chance of six to 11 named tropical storms or hurricanes, which he said is far fewer than average.

El Nino creates unfavorable winds in the Atlantic Ocean and Caribbean Sea for hurricanes and tropical storms, Zierden said, and that’s proving true this time.

“It is really a hostile environment out there for hurricane formation right now,” he said.

John Christy, Alabama state climatologist and director of the Earth System Science Center at the University of Alabama in Huntsville, said surface water temperatures showing record warming from El Nino were puzzling when most of the atmospheric temperatures were not as high.

He also said there was an 85 percent chance of above normal rain in the southeast from El Nino.

“In climate forecasting, it’s just through the roof,” he said.

Zierden agreed the El Nino forecast was strong, saying any summer response to El Nino is more uncertain and inconsistent. But in the winter, and with this strong El Nino, the forecast is more certain.

“I’ve heard these El Ninos events called a forecast of opportunity,” Zierden said. “It’s kind of a rare opportunity to make one of the best, most accurate and strongest forecasts that you can.”

(Story and copyrighted by Bruce Ritchie and Floridaenvironments.com. Do not copy or redistribute without permission, which can be obtained from bruceBritchie@gmail.com.)

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