All Eyes to the Sky

February 11, 2012 07:09 AM
 
pC2 All Eyes to the Sky

Climatologists anxiously track weather patterns

Mother Nature might be a bit kinder this spring than last, as experts have guarded optimism for relief from the effects of the weather phenomenon known as La Niña.

"We’ve seen some decent rains in some of our worst-hit areas this year that we didn’t get last year," says Brian Fuchs, a climatologist with the National Drought Mitigation Center (NDMC) at the University of Nebraska. "Also, when you see a second La Niña signal following a strong previous one, the second typically is not as significant, and this seems to be the case."

Concerns remain. Some weather experts still have concerns for this spring, though. Rains have helped the winter wheat crop in Oklahoma, but the Panhandle and extreme southwest Oklahoma are still in the most severe drought classification, says Renee McPherson, Oklahoma state climatologist. The western third of the state remains in extreme drought, the second highest classification. Rainfall has helped, but "the western two-thirds of the state remain at risk for a severe drought this spring," McPherson says.

It’s not only hard-hit states such as Oklahoma and Texas that are at risk for severe drought this spring. Very dry pockets also exist in northwest Iowa, southern Minnesota, northeast Nebraska and eastern South Dakota and are very much at risk, says Al Dutcher, Nebraska state climatologist. Some of these areas have looked at a departure from 5" to 6" to as much as 9" of rainfall from the period beginning Oct. 1, 2011, to early January.

Dutcher’s biggest fear for spring is what’s called a split-flow pattern, in which fronts and rainfall would miss the Plains and the western Corn Belt, like it did last year, but dump high
levels of rain in the Ohio Valley.

"It could be as bad as last year this spring," he says. "I look for below-normal rainfall and above-normal temperatures for the southern U.S. this spring due to La Niña," says John Nielsen-Gammon, Texas state climatologist. Because of that, he suggests farmers consider more drought-tolerant crops, such as sorghum and cotton, rather than corn. "There is no deep soil moisture yet," he says. Over much of the state, rainfall remains 75% of normal compared to just 45% of normal in 2011, which set a 12-month record for lack of rainfall. Meanwhile, Nielsen-Gammon notes, West Texas and the southern part of the state missed fall and winter rains and remain in extreme drought.
 

Atypical Niña. In North Dakota, La Niña years are supposed to mean cold, wet winters and wetter than normal springs. December 2011, however, was the 13th driest since records began being kept in 1890.

"It’s a very unusual year," says Adnan Akyuz, North Dakota state climatologist at North Dakota State University. "The Sept. 1 to Jan. 8 period was the warmest in Fargo’s history and the fifth most snowless."

Because this is such an atypical La Niña, Akyuz thinks the odds favor a drier than normal spring, despite contrary predictions from the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

Parts of South Dakota remain dry, which Dennis Todey, South Dakota state climatologist, fears might continue. As a result, farmers might want to consider dropping plant populations this spring, he says.

In Minnesota, soils are so dry that even the likelihood of above-normal spring rainfall will be insufficient to fully recharge the soils, says Mark Seeley, University of Minnesota Extension climatologist.

"Soils have no moisture for the first 3' or deeper," he says, adding that there is potential for early spring field work but fewer days to get it done.

The good news, including less than normal snowfall in the Rockies and low rainfall levels, is that Missouri River levels have subsided and, in many areas, farmland that was under water has dried out.

That’s the case in Iowa as well, says Harry Hillaker, Iowa state climatologist. For farmland next to the river, however, damage was so severe that those areas won’t be planted this year. That’s also true in Nebraska, where producers must recondition soils by removing the top layer of sand that was deposited during flooding.

Two things concern experts, however: Missouri River water levels still remain above normal, and the highest levels of snowfall normally occur in February and March.

Saturated soils in Ohio Valley. The situation couldn’t be more different in the Ohio Valley, affecting Ohio, Indiana and Michigan. "Soils are exceptionally wet," says Jeff Andresen, Michigan state climatologist. Record-setting rainfall in 2011, combined with an unusually wet fall, left soils absolutely saturated. Without a prolonged spell of dry weather, "there will likely be planting delays this spring," he predicts. "Producers will need to carefully monitor soil moisture conditions and avoid traffic on overly wet soils."

Iowa is a case of the haves and have-not’s, Hillaker says. "The northwest third of the state is really dry. Even normal spring precipitation will leave it dry."

The area normally gets 15" of rain in summer and fall, but in 2011 it got only 4". Southeast Iowa, however, had plenty of rain. Hillaker says it’s a coin flip as to what will happen this spring.

During La Niña years, the state is wetter than normal 60% of the time. "La Niña has a split personality when it comes to Iowa," Hillaker says.

A concern in Illinois in mid-January was that soils were still thawed. Jim Angel, state climatologist, has had calls that pests might not be frozen and killed as a result. "That’s not quite as serious an issue as you think. Pests dig deep to survive anyway, and many are killed during spring rains," he says.

Angel expects a wetter than normal spring, not so much due to La Niña, which he says is "fizzling out," but to data from the past five to 10 years that show wetter spring conditions. Unlike the Ohio Valley, most Illinois soils, while fully charged, are not saturated enough to create planting problems.

During May through July, Minnesota’s Seeley predicts that La Niña will subside, with weather moving back to a neutral pattern. "Later in the year, El Niño is likely to return."

 

GRACE Under Drought Pressure

Tracking La Niña’s effects upon farmland are two points of light, one behind the other in an orbital chase across the night sky. Those two lights are the Gravity Recovery and Climate Experiment (GRACE) satellites, which are mapping our planet’s ever-changing gravity field 310 miles above the Earth. Traveling 137 miles apart, the satellites detect small changes in Earth’s gravity field caused by the redistribution of water on and beneath the land’s surface.

The satellite’s signals are monitored by NASA’s Jet Propulsion Lab and the University of Texas Center for Space Research and then merged with a substantial weather database to measure current gradients of soil moisture and groundwater.

Brian Fuchs of the National Drought Mitigation Center says the center will be watching the La Niña signal strength closely from late February through the first part of April, when the effect typically dies out.

How do other climatologists assess the center’s data? "The drought monitor is as good as you can get, but drought outlook is a work in progress; it has a ways to go," says Jim Angel, Illinois state climatologist.
 

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