Ice gathers between crop rows last winter in Arizona's Yuma Valley region.
Ice gathers between crop rows last winter in Arizona's Yuma Valley region.

A new forecasting system from the University of Arizona should be ready in time for the start of the next Yuma lettuce harvest, giving growers a heads up on where to send crews each morning.

That could avoid idle workers and waiting for ice to melt in fields, saving growers money on labor.

The project, funded by an $88,000 grant from the U.S. Department of Agriculture, should provide higher-resolution, satellite-image forecasts to a scale of about 1 to 1.5 kilometers, said Paul Brown, extension specialist in biometeorology at the university.

 “We’re going from the standard resolutions that the National Weather Service and others are operating at and moving it to a much finer resolution so we can pick up the details of nighttime temperature and airflow,” said Brown.

While researchers nationwide have contributed to the forecasting model, Brown said, atmospheric scientists at the university have adjusted its parameters for arid-region conditions as well as higher resolution.

“We’re refining it further right in and over produce fields for better forecasts at the level of vegetation,” said Brown. “The main driver behind this is being able to dispatch picking crews to a proper location in the early morning hours and not have to wait for ice to thaw. There’s quite a variation in temperature throughout that (Yuma) area.”

John D’Arrigo, president of D’Arrigo Bros. Co., Salinas, Calif., said he’d welcome more precise forecasts.

“You never want to cut anything with ice,” he said. “We hate for people to get up early, go to a field and just wait. There were times this last winter when we waited all morning — three hours or more. You’ve got to pay them. It’s short days and a small window to harvest.”

“I hope they perfect it,” D’Arrigo said. “An accurate forecast is just more efficient on all your inputs — labor, fuel, buses.”

Doug Classen, sales manager at The Nunes Co., Salinas, Calif., agreed.

“It’s extremely important for scheduling harvests to know when that ice is going to hit,” he said. “We watch weather reports constantly.”

Whatever assumptions people might have about the Southwest or deserts, Arizona’s growing region is divided into distinct microclimates, D’Arrigo said, making small-scale forecasting all the more desirable.

“You’ve got an entirely different weather pattern from the upper to the lower Yuma Valley,” D’Arrigo said. “The north is warmer, closer to the river. And you’ve got the Gila Valley.”

The lettuce ice forecast system will be available by the Web around Nov. 1, Brown said, and continue through the Yuma deal into March or April.

Under a prior model, the university’s Department of Atmospheric Sciences website began offering an hourly forecast for growers last year.

“Our plan would be to repeat that so they can get online any day for a text-based or map-based forecast for the next 48 hours,” Brown said.

Meteorologists plan to meet with growers in the summer or fall to discuss additional delivery options, such as text messaging or Twitter transfers, Brown said.

As the model is perfected, possible future developments include near-surface humidity forecasting, which could be relevant to plant disease issues; and uses by the alternative-energy industry for solar and wind power.