It’s back! The wet season has arrived; First warning for the heavy commute Friday

I certainly wouldn’t call it “spooky” weather today in honor of Halloween, but as I was getting ready for work I definitely noticed that my house was dark at 1:00 PM! We had thick clouds overhead as a cold front passed through the metro area. Yes, the dark time of year has arrived here and that includes lots of clouds, rainy spells and cooler days. Today was our coolest day in almost 7 months, with late afternoon temperatures barely above 50°. This could easily have been a “mild” midwinter day.

Take a look at the rain over the past 7 days; All of us in the metro area have received an inch and some parts of the outer SE metro (Happy Valley/Damascus) have received over 2.00 inches.

and check out all those 3″+ totals in the mountains around us. Fire season 2024 is a memory…

What awaits us?

Rain, and lots of it, over the next two days. A cool/unstable air mass is moving over the Pacific Northwest. An upper level low (dip in the polar jet stream) will be offshore and then move inland over the next three days.

There will be an intensification of showers both tomorrow afternoon and Friday morning as energy waves rotate through the bottom of the trench. There have even been hints on several models and several runs that a weak surface layer could develop and move somewhere inland into NW Oregon or SW Washington. The impact would be heavy rainfall somewhere in the region during Friday morning’s ride. We could also see southerly gusts in the 55-50 mph range for a few hours during the morning commute, mainly from the southern metro into the Willamette Valley. This would cause a few tree branches to end up in power lines in some places = power outages. Decreasing easterly winds will likely remain in place for much of the metro area, keeping southerly winds from becoming too strong. Our evening GRAF model is slightly stronger than previous runs; no storms, but lots of wind during the Friday morning commute south of Portland.

There’s a good chance we’ll double last week’s rain totals over the next two days. That’s 1-2″ of rain in the western valleys! If we already had saturated ground and rivers high in the middle of winter, that could be a problem for localized flooding by Friday afternoon. But because the ground is still relatively dry, all our trees/shrubs/lawns will receive much-needed rain. Sure, 1-2″ of rain spread over two days is okay, but if we get 1″ of rain in a few hours, it could cause urban/local flooding. The same model shown above will produce approximately 1.00″ of rain in both Salem and Portland between midnight Thursday night and the end of the run Friday morning. Much of that will fall BEFORE the commute, but even 1/2″ of rain plus a breezy southerly wind will make for a nasty first trip of November! For this reason, we are declaring a FIRST ALERT WEATHER DAY (MORNING) on Friday morning. Not a big storm, but it WILL impact your life. This is especially true if you lose power due to gusty winds!

MOUNTAIN SNOW

It is not unusual to see snow all the way to the passes in late October or early November, but every year is VERY different. Take a look at the snowfall from November 1 to 15 at Government Camp over the past 30 years. Some years no snow falls, other years it piles up several meters and the ski season starts early. Last year none fell in the first two weeks of the month.

Snow levels will remain near or above the passes for the next two days with all the showers. I expect 6-10″ at Government Camp, and 12-18″ on the higher slopes of Mt. Hood resort (5,000-6,000′). WAY above that, about 6,500 feet and higher, 20-30″ will fall. If you drive over the passes over the next two days, it will likely snow in the morning, but expect mostly slush or wet roads in the afternoon and afternoon. The Santiam and Willamette passes are slightly higher, so snow cover will continue there each day.

MILDER AND DRIER NEXT WEEK

Another weak upper level trough moves through Saturday before lighter showers, after which we will GENERALLY be heading for a ridge setup near or just offshore. This creates weak weather systems or dry weather. Next week you can see the higher than normal highs in this seven-day average of the Euro ensembles