Yuma County weather is significantly different due to micro-climates. Irrigated farm land that backs up to mountain ranges and the summer monsoon (rainy) season generate varied moisture levels and temperatures. 

Summer can sizzle in the 115 to 120 degree range. Winter daytime highs in the 60s to the 80s are commonplace and ideal for growing high quality winter lettuce.

The just-completed winter lettuce season was the initial test of the lettuce ice forecast system. The UA weather model divided the earth’s surface into layered grid areas. Data were sent to a powerful weather modeling computer and server where complex mathematical equations transformed the data into valuable agricultural weather forecasts.

“It’s a benefit to local growers to know where ice is forecast so the logistics can be arranged for delivering field workers to particular locations,” Nolte says. “If lettuce ice is forecast for the south Yuma Valley for four hours in the morning, harvest crews can be sent to a field unaffected by lettuce ice, or perhaps begin work later in the morning. This enables greater efficiency and can reduce costs for the grower.”

The online forecasting and monitoring information can also benefit lettuce shippers and buyers so they can make more informed decisions on lettuce harvests and purchases, he says.

The UA weather system replaces a National Weather Service system discontinued in Yuma County about 15 years ago. The new system was developed with a three-year, $88,000 specialty crops grant from the Arizona Department of Agriculture.

Weather monitoring stations cost about $3,000, plus an additional $2,000 annually for upkeep and management. Funding for the UA lettuce ice program will run out following the 2011-2012 lettuce season, and new funding dollars will be sought from the private lettuce industry.

Another idea is to expand the weather program beyond the winter months to a year-long program in order to service summer cropping systems.

“We could provide weather services for the melon and cotton industries, especially with the growing interest in expanding cotton acreage,” Brown says. “We can examine the potential benefits and discuss the program with commodity groups for possible financial support.”

Heat stress is a major issue in cotton, Nolte says; excessive heat and humidity can cause cotton flower abortion.

“Accurate weather forecasts and monitoring information could provide growers with timely information that would allow them to pursue possible solutions to generate higher crop yields.”

This summer, Brown will meet with lettuce growers to gain feedback on the first year of operation and to provide training on the web-based program and data interpretation.

He is exploring new ways to disseminate weather information, including text messaging and social media sites, including Facebook and Twitter.

To view the 48-hour weather forecast movie, go online and use the following link: www.atmo.arizona.edu/index.php?section=weather&id=wff.

To view online weather monitor information, use this link: http://ag.arizona.edu/azmet/ls.htm.