By Nicole Montesano • Staff Writer • 

A hard rain's gonna fall

The next major rain is expected to arrive Friday and stick around through the weekend. The National Weather Service has issued a special weather statement, noting, “This could be the most rain most areas in Southwest Washington and Northwest Oregon have seen since March.”

The Weather Service lists the chance of rain at 60 percent Friday, 80 percent Friday night and Saturday, and 90 percent Saturday night. The parched Willamette Valley could get half an inch or more, the agency said, and up to two inches could fall along the coast.

The likelihood of showers is expected to persist through Wednesday, as one front gives way to another.

A low pressure system off the coast is moving onshore. It is expected to begin producing significant rainfall Friday night, continuing through Saturday.

A second system is expected to roll in Saturday night and linger through Sunday. Afternoon temperatures are expected to hover in the 70s, breaking a run of highs in the 80s, 90s and 100s.

That change represents good news for firefighters, who have been overtaxed by one of the worst fire seasons on record across the West.

More than 350,000 acres are currently ablaze in Oregon alone. A 230-acre wildfire north of Willamina is nearing containment, but several other fires are still burning out of control.

Unfortunately, the weather shift isn’t likely to do much to relieve Oregon’s drought conditions, rated severe in the Willamette Valley and extreme in much of the rest of the state. The land is so parched it may take years to restore depleted soil moisture, according to hydrologists.

The rainfall may create slick road conditions for motorists, the Weather Service warned.

“Oils that have built up on roadways during the extensive period of dry weather this summer will cause them to be extra slippery during the first part of the rain event,” the agency said. It warned motorists to ease up and exercise caution.

The rain also represents a mixed blessing for vintners waiting for winegrapes to ripen.

David Adelsheim, president at Adelsheim Vineyard in Newberg, said rain could cause some splitting, rotting or dilution of flavor. However, he said it won’t induce vineyards to pick early.

“One thing we’ve definitely learned over the years is, you don’t pick unripe grapes before a predicted rain, because you’re never going to make unripe grapes into ripe wines,” he said.

Adelsheim said some vineyards, including his, have started harvesting a few blocks unseasonably early, but not the majority.

He began picking in one area Thursday “for a nascent sparkling wine” program, he said, but is not likely to begin harvesting his main varieties yet. He said his vineyard manager and winemaker are comparing notes, monitoring the grapes and the weather forecasts and planning for various contingencies, such as how to deal with tractors on wet soil.

Generally, he said, the fields being harvested now “are either unusually stressed, very young, or very early sites with low crop levels.” He said, “I don’t think most people have started legitimate harvest of red grapes to make serious wine.”

However, Adelsheim said climate change “has moved everything forward,” making it harder to predict. “I can’t tell you anymore what normal is,” he said.

Typically, he said, the vineyard begins harvesting around mid-September. However, he noted, “We had the coolest growing season ever in 2010, the latest growing season in 2011, and now we’ve had the three warmest, or likely to be the warmest, growing seasons ever, on top of each other.”

This year, he said, featured the earliest bud break and earliest bloom, and with the picking that started on Thursday, the earliest harvest.

“It’s hard to know what normal is, when everything is so different,” he said.