WSU ag meteorologists call 2011 "A Tale of Two Summers"

It was a tale of two summers in central and eastern Washington. Following a cool June and July, August warmed up in central Washington, report Washington State University agricultural meteorologists Gerrit Hoogenboom and Nic Loyd. “It’s easy to be a casual observer of weather patterns, but we like to see the numbers,” said Hogenboom, director of WSU AgWeatherNet. “Especially for farmers, but for many others as well, knowing how weather patterns are trending is key in making economically important decisions.”

“August was seasonally hot and dry in central Washington, as the region returned to a more typical late summer weather pattern featuring high temperatures generally in the upper 80s to lower 90s. In fact, daily high temperatures were up to 2.2 degrees above normal during August,” said Loyd. The century mark was finally reached Aug. 26-27, with WSU AgWeatherNet’s Orondo station (north of Wenatchee) reporting 101.5 degree on Aug. 27.

In eastern Washington, August temperatures were above normal while western Washington was slightly cooler than usual.

“It really was a tale of two summers,” said Loyd. “Overall, the summer (June through August) temperatures were equally below normal during the day and night by about one and a half degrees. However, the season was dichotomous with two separate temperature patterns. The summer season featured numerous bouts of cool daytime weather in June and July due to a greater than normal influx of Pacific air into the Northwest, while the central and eastern United States endured oppressive heat. The Northwest began to warm in August, as the rest of the nation received a reprieve from the scorching heat of July. Fewer Pacific weather systems passed through central Washington and so there was less cooling influence from the Pacific Ocean, which caused above normal temperatures.”

Normally, August is slightly cooler than July – but not this year, in which August was the warmest month of the year and indeed the warmest August in five years. “This warm weather was the result of the periodic presence of a stable ridge of high pressure that became more dominant in the month of August,” said Loyd.

At the WSU Irrigated Agriculture Research and Extension Center in Prosser, where AgWeatherNet director Hoogenboom and meteorologist Loyd are based, there were six consecutive months of below normal temperatures in the period ending in July.

“There were a couple notable events this summer,” Loyd said. “On June 8, the high in Prosser was a chilly 64.5 degrees. And on July 25, there was intense rainfall – a quarter of an inch in 15 minutes – associated with a cold weather system.”

For farmers, the news is mixed. Initial reports indicate that the 2011 Washington apple crop will be down a few percent compared to last year due to the cool and wet spring. By contrast, a 20 percent decrease in wine and juice grape production in 2011 has been observed due to damage received during the autumn freeze in November 2010.

However, pear growers report good bloom and fruit set, along with excellent fruit quality this year. Overall, despite a cool spring and an initially delayed growing season, the summer growing conditions have been excellent, and Washington prune production is expected to increase in 2011. Although the anomalous weather had some effect on peaches, they have generally matured well. Fruit quality and sizing was helped early on by the slow and cool growing season.

AgWeatherNet is available online at http://www.weather.wsu.edu.