Update posted at 8:30 a.m. Sept. 17
A significant change in the region's weather is taking place today.
The National Weather Service (NWS) Portland issued a Special Weather Statement this week forecasting rain and cooler temperatures.
"Rainy days are in store." The NWS Tweeted earlier this morning. "Take a look at our forecast rainfall totals from today through Monday morning. Remember to exercise caution when driving on newly-wet surfaces."
Public Works officials across the region caution that the heavy rain could trigger flooding and landslides.
Travelers are reminded to slow down, especially through high water. Driving through several inches of water at high speed can cause you to lose control of the car; it could also splash water into the engine and stall it. Going fast through high water can also cause wakes which can be hazardous to other vehicles. Lowering your speed helps you prepare for sudden stops caused by disabled cars, debris and other wet-weather hazards.
Previous coverage post Sept. 16
The National Weather Service has issued a Special Weather Statement for much of Oregon.
"With the first storm system of the season due to arrive this weekend, we are generally expecting 1-2" of rain in the Willamette Valley from late Friday through late Sunday. 2-3" of rain will likely fall along the coast with locally higher amounts in the Coast Range an Cascades," The NWS Portland said in a TWEET.
In the Special Weather Statement, the NWS said the approaching weather pattern will include a series of strong, wet cold fronts will bring an end to the long dry and hot summer.
Overnight temperatures will cool into the lower to mid 40s tonight, with some of our more exposed and traditionally cooler locales dropping down into the 30s. With the potential of frost in outlying rural areas, consider taking time and precautions to protect any temperature sensitive plants. Afternoon high temperatures will be in the 70s through Thursday, then cool to the 60s for Friday into this weekend.
A strong cold front will push into the region Friday night, bringing the first significant widespread rain to the region since last spring. Rain may be heavy along the front, and may be heavy enough to cause localized debris flows in recently burned areas.
Elsewhere, heavy rainfall rates Friday night may lead to some ponding on roadways and minor urban flooding issues in areas of poor drainage.
Overall expected rainfall amounts may still be adjusted between now and the event, but at this point 1 to 2 inches of rain are expected for the inland valleys by Monday morning, with 2 to 4 inches possible along the coast and across the higher terrain.
With the expected rainfall, any clogged drains or gutters could easily overfill. With the dry weather through Thursday, consider checking outdoor drains, roof gutters, and other areas with poor drainage and clearing out the dead leaves and debris.