Warning issued for floods, debris flows
National Weather Service warns Oregon and Washington residents
The National Weather Service has issued a flood watch for Tuesday evening through Wednesday evening for rivers and creeks in Northwest Oregon and Southwest Washington.
The watch includes both floods and debris flows, which are rapidly moving landslides that can destroy everything in their paths. Debris flows can easily travel a mile or more, depending on the terrain. They will contain boulders and logs and transport those in a fast-moving soil and water slurry.
Flood watch area include range from the coast to the Columbia River Gorge, and include the Portland and Vancouver metropolitan areas.
According to the weather service, care should be taken when traveling over the mountains during this time. The most dangerous places include:
• Canyon bottoms, stream channels, and areas of rock and soil accumulation at the outlets of canyons.
• Bases of steep hillsides.
• Road cuts or other areas where slopes of hills have been excavated or over steepened.
• Places where slides or debris flows have occurred in the past.
The weather service says that during flood warnings, stay away from rivers, creeks and steep slopes during intense rainstorms. It advises that people take the following steps:
• Stay alert. Listen to the radio, TV, or a weather radio for flood watches, which include the potential for debris flows and if told to evacuate, do so immediately.
• Listen for unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together. A trickle of falling mud or debris may precede larger landslides.
• If you think there is danger of a landslide, leave immediately.
• If water in a river or stream suddenly turns muddy or the amount of water flowing suddenly decreases or increases, this is a warning that the flow has been affected upstream. You should immediately leave the area because a debris flow may soon be coming downstream.
• Assume highways are not safe. Be alert when driving, especially at night. Don't overdrive your headlights. Embankments along roadsides may fail, sending rock and debris onto the road.
• Landowners and road managers should check road drainage systems and conduct needed maintenance in case the predicted heavy precipitation does occur.
Cleaning up after landslides can also be hazardous, the weather service says: "When it is wet outside, be careful when cleaning up the mess. A small mudslide can actually be part of a larger landslide. Cleanup should not be done until after the storm.'