Potential flooding possible Nov. 10-12 as heavy rains hit Northwest Oregon
Residents of Northwest Oregon are advised to be on alert as heavy rains forecasted for tonight through Friday could create potential hazards.
While representatives of the Natural Resources Conservation Service in Oregon have expressed optimism about water year's precipitation levels so far, hydrologist Scott Oviatt explains that there is concern this week about having "too much rain."
Starting at 5 p.m. Wednesday, Nov. 10, and continuing through Friday, Nov. 12, the National Weather Service says there is a chance for creeks and rivers in the region to flood, especially in the coastal terrain and the Cascades.
"We've been having a lot of storm impacts (in recent years)," Oviatt said on Nov. 9. "We're at 89% of median volume of precipitation."
In just the past day, that percentage has risen to 94% in the Hood, Sandy and Lower Deschutes region.
While the fact that the Clackamas River, Little Sandy River and Sandy River were all at above historic median volumes on Nov. 9, was promising to Oviatt, but with potential for an extended rain event, he and others are worried that the streams in the region may not be able to handle the influx of one to two inches of rain accumulation forecasted to accumulate overnight.
"We seem to be seeing more and more of these extreme events," Oviatt added. "Our big problem is these extremes."
A flood watch will be in effect starting at noon Thursday, Nov. 11 until 6 a.m. Saturday, Nov. 13.
"An atmospheric river event will bring increasing rainfall starting this evening through Friday night," the NWS reported Wednesday afternoon. "However, the heaviest rain, compounding impacts to rivers, will likely begin Thursday afternoon. Snow levels will rise to above 9,000 feet, bringing the possibility of heavy rain and flooding to the higher elevations."
"Heavy rain can trigger debris flows and landslides in steep terrain, and the risk is higher in wildfire burn areas," said representatives with Oregon's Office of Emergency Management. "There is potential for debris flows in the burned areas of the Cascades, including the Riverside, Beachie Creek and Lionshead fire sites. Eagle Creek and Holiday Farm fire areas may also be potentially impacted. The public can remain safe using basic preparedness actions, including staying informed, being aware of surroundings, having a plan for emergencies and being prepared with an emergency kit."
Ways to stay informed during these events include:
"If told to evacuate, do so immediately," emergency management representatives advised. Those who are told to evacuate are encouraged to drive with caution and be aware of the latest road conditions before driving by checking tripcheck.com.
"(Drivers should also) be alert when driving; embankments along roadsides may fail, sending rock and debris onto the road," emergency management representatives added. "Turn on lights, increase following distance and slow down.
Don't drive through flood water; just 6 inches of fast-moving flood water can knock over an adult, and a foot of rushing water can carry away most cars."
Residents are also encouraged to heed flood watches and warnings and know what signs to look for in case of a landslide.
For more information about flood risk and mitigation, visit ready.gov/floods. For information on landslides and debris flow, visit ready.gov/landslides-debris-flow. For information on flood insurance, floodsmart.gov.
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