New techniques may improve ability to forecast weather events
CHICAGO, Ill. (Reuters) — Last year’s drought in the United States, which was the country’s worst since the Dust Bowl years of the 1930s, sent world food prices to record highs.
The long, dry summer also cost the government a record $16 billion in crop insurance payments. The Mississippi River shrank in the heat, and barge traffic slowed to a trickle.
U.S. weather forecasters never saw it coming.
That’s why this year, as spring seeding begins, meteorologists are adjusting forecasting techniques, trying to learn from what went wrong last summer and using 2012 weather data for what they hope will be an improved early alert system.
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“The drought of 2012 was such a singularity, only repeated a few times in a century,” said Harvey Freese, a top private weather forecaster.
“The temperature and precipitation departures were two standard deviations from normal. The year 1934 did begin to show up in our analog comparisons of past years, but we probably only dared to think about the possibility.”
Forecasters and their customers say improvement is needed over what happened during the first half of 2012.
“People are calling it a ‘flash drought’ because it developed so suddenly,” Siegfried Schubert, a senior research scientist for NASA, said as he recalled the dry season that started in the winter, persisted through the spring and summer and continues in the western corn belt and southern U.S. Plains.
“I don’t think there were any models that predicted that.”
Well-established agricultural forecasting services such as MDA EarthSat Weather, Commodity Weather Group, World Weather and Freese-Notis were caught by surprise.
Commodity traders and grain analysts pay for forecasts that can be reliable as far as three months in advance, but none of the firms gave advance notice of last year’s drought during the winter or early spring.
Meteorologists rely on esoteric weather conditions to forecast long-term U.S. weather trends, such as the La Nina and El Nino phenomena tied to changes in southern Pacific Ocean surface temperatures.
A year ago, forecasters said the second strongest La Nina in history faded in the winter of 2012 when sea surface temperatures began to warm.
Meteorologists took that as a sign that the U.S. crop belt should experience a fairly normal growing season, but they ignored atmospheric data that might have tipped them to the impending drought.
“Even though the oceans were acting like they were not in La Nina any more, the atmosphere was acting like we were,” said Joel Widenor, agricultural director for Commodity Weather Group. “Unfortunately, we didn’t pay attention to that soon enough to adjust our forecast last spring. It’s something we’re watching this year. We think it was a pretty big factor last year.”
Widenor calls it the GLAAM factor. He has tweaked his forecasting techniques for this season using the global atmospheric angular momen-tum, an atmospheric index that measures the spinning of the Earth and its effect on weather.
Hoping to catch signs of a drought earlier, he is also watching the weekly U.S. Drought Monitor, which tracks soil moisture and water temperatures in the northern Pacific Ocean, off the coast of Baja California and the northwestern Atlantic Ocean.
Don Keeney, EarthSat’s senior meteorologist, said his firm is studying previous big drought years and comparing them with current patterns, looking for any sign that drought-prone conditions will continue.
However, meteorologists and climatologists, who study the interaction of the sun, the atmosphere and the Earth, readily admit 2013 will be another tricky year to predict because La Nina and El Nino patterns this winter have been neutral. It boils down to educated guesswork or hunches based on years of experience.
Iowa State University climatologist Elwynn Taylor looked at the La Nina trends in March 2012 and updated his prediction for a major drought to a 50-50 probability from 30-50.
He said the western Midwest is set up for another hot, dry summer this year, citing La Nina history. Rock hard soil several feet below the surface are another flag the droughty conditions could continue this season, he added.
Taylor’s outlook aligns with recent comments from Nebraska state climatologist Al Dutcher, who said that state’s 10 million acre corn crop stands or falls on irrigation as well as rain.
In fact, most weather forecasting models, including the U.S. government’s, are now leaning toward a hot, dry summer for the U.S. crop belt, especially west of the Mississippi River.
However, last year’s failures have left grain market analysts worrying about this year’s forecasts. They need to balance the longer trends with the way a sudden shower can affect markets day to day.
“We all know that the long-term guidance is not as reliable as near-term patterns,” said Rich Feltes, an analyst at giant broker RJ O’Brien.
“We also know nothing is more riveting to the markets than what the last 24 hours precipitation and temperatures have been relative to expectations.”
While analysts say calculators to crunch data on long-term patterns are important, they must always give greater weight to short-term weather forecasts because most commodity traders think short-term. Volatile grain markets reflect that reality.
“Weather forecasts 12 to 15 days out are not terribly reliable. The forecaster we use points that out constantly,” said Anne Frick, oilseed analyst at Jefferies Bache in New York.
“For three days out, very high confidence. Up to seven days: confidence. Beyond the seven to 10 day period, it gets quite iffy.”
Schubert, who heads a group of scientists researching weather forecasting models, said last year’s poor performance should not cause anyone to dismiss long-term forecasting altogether.
He said a review of NASA data shows that one of its research models tracking soil moisture did begin picking up signals of extreme drought by early May.
“Even if we can’t predict an event like last year’s drought, perhaps we can predict the probability of an event happening,” Schubert said.
“Ultimately, that is our goal.”
