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Northwest vineyards track along 2017 vintage after cool July
Portions of the Pacific Northwest saw wildfire smoke waft in during July and ahead of scorching summer temperatures as growing degree days for the 2019 vintage are tracking similar to 2017 in many vineyards.
Climate researcher Greg Jones, director of the Evenstad Center for Wine Education and Evenstad Chair in Wine Studies at Linfield College in McMinnville, Ore., pointed out that July was a relatively mild month with low heat stress in vineyards, compared to the 2018 vintage. Those cooler temperatures brought little precipitation, however, to the Pacific Northwest, leading to early-season wildfires in Southern Oregon and Eastern Washington.
“The month was moderate to extremely dry, increasing concerns for ongoing dry conditions in the PNW and the fire risk across the west,” Jones wrote in his Weather and Climate Summary and Forecast for August 2019.
He noted that while Alaska, portions of Siberia, the Arctic and much of Europe sweltered in extreme record-breaking heat, the West Coast experienced a relatively mild, seasonal month.
Walla Walla Community College will play host to a free public lecture by Jones at 7 p.m. Wednesday. Jones is among Wine Business Monthly magazine’s Top 50 Wine Industry leaders in each of the past three years. His lecture is titled Grapes and Wine: Structure, Suitability, and Sustainability in a Changing Climate.
Growing degree days slot alongside 2017
This spring, growing degree day charts throughout the Pacific Northwest were headed in record territory, but the numbers have slowed at weather stations monitored by Jones throughout Oregon wine country and tracked by Washington State University’s AgWeatherNet across its 177 stations.
At this point, the hottest growing region is Washington state appears to be the Wahluke Slope. Through July 31, there were 1,998 growing degrees days recorded at the Wahluke Slope station. A year ago, that total was 2,208. In 2017, it charted 2,003 GDD. During the broiling 2015 vintage, it stood at 2,469 when August began.
At the Benton City station near Red Mountain, there were 1974 GDD – just one tick ahead of the 2017 vintage. A year ago, it stood at 2,131 GDD. In 2015, there were 2,357 GDD.
On Snipes Mountain in the Yakima Valley, there were 1,858 GDD registered. A year ago, it was 2,061 GDD. On that date in 2017, the accumulation stood at 1,860 GDD. During the blistering 2015 season, it was 2,312.
In the Horse Heaven Hills, the station at Phinny Hill picked up 1,841 GDD by July 31. A year ago, it was 1,910. In 2017, it was 1,742. A closer match would be in 2016 at 1,885, but in historically hot 2015 – the first year of that device near famed Champoux Vineyards – it captured 2,074 GDD.
The Pullman school’s 21 Acres station in Woodinville collected 1,048 GDD, compared with 1,164 of a year ago and 1,001 GDD from 2017. Back in 2015, it received 1,338.
In the Columbia Gorge, Skamania County’s Stevenson station notched 1,472 GDD. A year ago, it stood at 1,630, but in 2017 it counted 1,447. During the scorcher of 2015, however, it had reached 1,758 to start August.
Despite the cooler July, the warm start to the 2019 growing season has many areas of the Northwest from 50 to 200 growing-degree days above of the 1981-2010 average.
In the Walla Walla Valley town of Milton-Freewater, Ore., there were 1,859 GDD through July 31. A year ago, they stood at 2,062. At the same stage in the record-hot vintage of 2015, there were 2,317 cumulative growing degree days.
In McMinnville, the home of Linfield College and the heart of Willamette Valley’s Pinot Noir territory, there were 1,271 growing degree days — which is just ahead of the 1981-2010 average but well off the 1,574 of 2015. In 2017, the figure was 1,295.
This year, Roseburg stood at 1,758 on July 31. A year ago, it was 1,767, well above the 1981-2010 average of 1,427 but nearly 250 GDD off the hot 2015. And the Rogue Valley station in Medford recorded 1,891 GDD, more than 200 below that of 2015, and nearly a 100 off that the 1,972 of 2018. In 2017, it was 2,010.
“Heat accumulation (GDD) amounts for four locations that I have tracked for many years in Oregon have slowed during the last month,” Jones wrote. ” GDD is currently 10-25% above the 1981-2010 normals for the months of April through July, from 1-10% lower than the same point in 2018, and now running below 2015, the warmest year to date in the regions.”
Drought concerns ramp up as harvest approaches
Véraison is well underway in California, it is expected to be widespread during the second week of August for most of Oregon and Washington, Jones said.
“Véraison reports and estimates point to an average to slightly delayed vintage,” Jones wrote. “The forecast through mid-month indicates a warm start to August becoming seasonal through mid-month then warming to slightly above average later in the month with no major heat events. Some precipitation is forecast for the extreme northwest, but not much expected, while the rest of the west should stay dry.”
That forecast is driven by “a very warm North Pacific,” wrote Jones, who added that the Western U.S. is “likely seeing a warmer than average second half of summer and start to fall.”
The jet stream moved extremely warm air northward, and the West Coast’s normally dominant high-pressure dome shifted farther to the west and north, allowing for onshore flow from the North Pacific for much of the month.
“The return of the ‘blob’ of extremely warm ocean temperatures in the North Pacific should be a major influence in the 90 day forecast with a likely warm late summer, early fall for most of the west, but especially the PNW,” he wrote.
Cooler than average conditions have held in eastern Washington and Oregon, portions of southern California and into the desert southwest, Great Basin and Rockies. It’s also been a relatively dry water year for northwestern Oregon and Washington and some scattered areas in the northern Rockies (60-85% of average).
“In terms of the deviation in days, current conditions put much of northern California, western Oregon and western Washington 10-18 days ahead of normal for heat accumulation, while coastal areas in the North Coast, central to southern California, and eastern Washington are running 4-10 days behind in heat accumulation,” Jones wrote.
Unfortunately, there’s not much moisture on the horizon.
“The most significant area of drought concern continues to be western Washington, northwestern Oregon, and portions across the northern border areas with British Columbia,” Jones pointed out.