ORVALLIS - A rare convergence of weather events ended a 40-day dry spell in western Oregon by pulling the remnants of tropical storm Ignacio northward from California, according to Oregon State University's George Taylor, the state climatologist.
Over the past several days, Taylor said, Ignacio has crept north along the California coast. At the same time, a low pressure trough that had built over the Pacific Ocean moved eastward toward the Oregon coast.
And warm, offshore waters, coupled with an ongoing El Nino event in the tropics, added a third element.
"Events such as this are rare in Oregon," said Taylor, a faculty member in OSU's College of Oceanic and Atmospheric Sciences. "The combination of a tropical storm, unusually warm offshore waters, and an approaching low pressure trough seldom occurs.
"It is likely that the warm, moist air from Ignacio will produce significant thunderstorms in much of Oregon during the next several days, particularly in the Cascades," he added.
Taylor said the tropical storm triggered a lot of rain in California and brought a fair amount of moisture into Oregon. San Francisco reported .97 inches of rain on Tuesday, Aug. 19 - the largest one-day total ever recorded there in August.