Unusual wind burst topples trees in Oxbow's 'Ancient Forest'

GRESHAM, Ore. - An ancient forest that leads folks to a popular summer-time fishing hole and campground took a beating recently when what appears to have been an intense burst of wind swept through the trees, knocking some clean out of the ground and snapping others in half.

The weather event happened the evening of Saturday, March 28 along the winding road that takes anglers and campers through the middle of an old growth forest of 300- to 500-year-old trees and deposits them at Oxbow Regional Park along the Sandy River. The map below shows where the 'Ancient Forest' is located in relation to the rest of the park.  You can also view the Google Map.

"It was just kind of a really strange incident," said Park Ranger Kendra Carrillo.  "We sort of expect this out here.  We've had several storms over the course of this winter - a snowstorm, windstorm, flooding - but nothing to this extent where this many trees, old growth trees, have fallen."

In all, about 20 trees came crashing down or were sheered off at the top, many of them landing right across the road that leads to the campground.  No one was injured but Carrillo said there was a group of young adults who saw the first few trees fall.

"One of the girls actually told me that she was within a couple of feet of the first tree and at that point they decided they should probably get to a safer area," she said.

So What Exactly Happened?

The general consensus is that some type of quick, concentrated burst of wind struck the area that day.

"It is possible that a microburst or strong frontal band winds hit the area as a cold front pushed through," said KATU Meteorologist Rod Hill, who took a look at the weather statistics for that day and noted there was a front with some high winds.

Metro operates the park and their naturalists hypothesize that an extreme weather event called a microburst occurred sometime between 6:30 p.m. and 7:30 p.m. that day.  Microbursts are powerful downdrafts associated with thunderstorms.  Downdrafts are typically only a few hundred to a few thousand feet across and when they reach the ground, they spread out horizontally.  They usually last about 15 to 20 minutes.

• Learn more about microbursts and see diagrams of what they look like here (information provided by Metro).

The Landscape Is Different Now

Although the weather event didn't last long, it was powerful and the lasting effects will linger for years to come.  For one, much of the canopy along one stretch of the road is gone and when you look straight up you see sky instead of tree branches.  Sunlight now falls on portions of the road that used to be shaded.

"The canopy has just completely changed," said Lead Park Ranger Bill Doran, who has worked at Oxbow Regional Park for over 30 years and knows the landscape like the back of his hand.  He said he can't get over how different it is now. And his fellow park ranger, Kendra Carillo, has the same sentiment. 

"You look at that area and there is so much light coming in and you see these trees in the understory, these Douglas Firs, Western Red Cedars and Hemlocks that are now going to have the opportunity to mature," she said.  "Basically what it is is just the next stage in forest succession.  And it's awesome to be able to see that first-hand.  It really changes the dynamics down there.  It's a different structure.  But it's all a very natural process and cycle."

Folks passing through the ancient forest will likely not notice the difference in the canopy but what they will see are the fallen trees alongside the road.  It kind of looks like a logging operation because park staff used a chainsaw to clear the trees from the roadway.  A few campers were actually trapped inside the park the weekend the trees fell and park staff moved quickly to clear the way for them.  A couple of people who felt uncomfortable being there were hiked out.

Is The Park Still Safe?

Yes it is, although as with any park, campground or other recreational spot you can't always predict what Mother Nature will do.   Howard Rasmussen, an Arborist for Metro who keeps a close eye on the trees at Oxbow Regional Park, said folks should feel assured that everything is being done to keep them safe.

"I concentrate in areas where people concentrate," he said.  "I can never guarantee that nobody's going to get hurt and there is no such thing as a safe tree.  But I can make it safer with what I do.  Oxbow is still a safe park.  I just continue to watch it and to be vigilant about it."

Rasmussen said what happened a few weeks ago was an unusual event that no one could have foreseen.

"Arborists try to make hard science out of determining which trees are coming down and sometimes what actually happens defies logic," he said.  "Sometimes they are no-brainers and other times we'll have a big wind event and what comes down are the healthy trees and the dead, feeble-looking trees remain standing."

So What Happens Next?

Metro's long-term plan is to leave the fallen trees right where they are to deteriorate naturally so they can provide nutrients for new plant growth and habitat for wildlife.  However, some pieces will go to other areas of the park.  For example, some will be placed in or around the campground spots to help provide vegetative buffers between sites. 

To Visit The Park

Driving Directions

Nature Activities/Field Trips Metro hosts a number of educational activities at Oxbow Regional Park - animal tracking, forest walks, wildflower and mushroom identification classes and more. View their calendar.

• From Portland, head east on I-84.
• Take the Troutdale exit (17).
• Go past the truck stop to the light and turn right on 257th.
• Go three miles to Division Street and turn left.
• Continue east for five miles following the signs.
• Turn left on Oxbow Parkway and drive 1.6 miles to the park entrance.

Bike There

• Travel east using the bike lanes on Stark, Division or Powell, then continue east on Division to Gresham and follow the signs to the park.
• You can also take Springwater Trail east and travel north to Division using the bike lanes on Hogan Road.
• Bicycles are welcome in the park on paved roads and some marked trails.

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Shannon L. Cheesman is a Portland-area Web Producer/Reporter who specializes in the outdoors. She writes and reports for Fisher Interactive Network, which consists of 13 local news/information Web sites in Oregon, Washington, Idaho and California.