It's back! The rainy season is here; First warning for rough morning commute Friday

I certainly wouldn't call it “spooky” weather today in honor of Halloween, but as I headed to work I noticed that my house was dark at 1pm! We had thick cloud cover above us as a cold front moved across the city area. Yes, the darker season is upon us and that includes lots of clouds, periods of rain and cooler days. Today was our coolest day in almost seven months, with temperatures barely climbing above 50° in the late afternoon. This could easily have been a “mild” midwinter day.

Take a look at the rain for the last 7 days. We ALL in the metro area gained an inch and some parts of the outer southeast metro area (Happy Valley/Damascus) gained over 2.00 inches.

and look at all the 3″+ overall sizes in the mountains around us. The 2024 fire season is a reminder…

WHAT IS HAPPENING?

Rain, in abundance, the next two days. A cool/unstable air mass is moving across the Pacific Northwest. A high low (dip in the polar jet stream) is located offshore and will then move inland over the next three days.

Showers will intensify both tomorrow afternoon and more prominently Friday morning as waves of energy rotate through the bottom of the trough. There have even been indications across different models and different runs that a weak surface low could develop and move inland to somewhere in northwest Oregon or southwest Washington. The result would be heavy rain somewhere in the region during the Friday morning commute. We may also see southerly wind gusts in the 35 to 50 mph range for a few hours during the morning commute, primarily from the southern metro down into the Willamette Valley. This would cause a few branches to fall into the power lines in places = power outages. A decreasing easterly wind is likely to continue across much of the metropolitan area, preventing southerly winds from becoming too strong. Our GRAF evening model is slightly stronger than previous runs; No storm, but plenty of wind during the Friday morning commute south of Portland.

There's a good chance we'll double last week's rainfall amounts over the next two days. That’s 1-2″ of rain in the western valleys! If we had already saturated ground in the middle of winter and the rivers were flooding, that could be a problem for localized flooding on Friday afternoon. However, since the ground is still relatively dry, all of our trees/shrubs/lawns will soak up the much-needed rain. Of course, 1 to 2 inches of rain spread over two days is fine, but getting 1 inch of rain in just a few hours can cause urban/local flooding issues. The model shown above will produce approximately 1.00 inches of rain in both Salem and Portland between midnight Thursday evening and the end of commute time Friday morning. A lot of this will fall BEFORE the commute, but even 1/2″ of rain and a breezy southerly wind makes for an annoying first commute in November! For this reason, we refer to Friday morning as FIRST ALERT WEATHER DAY (MORNING). Not a major storm, but it WILL impact your life. This is especially true if you lose power due to the gusty wind!

MOUNTAIN SNOW

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

Snow depths will remain near or above the passes over the next two days with plenty of showers likely. I expect 6 to 10 inches at Government Camp and 12 to 18 inches on the higher slopes of Mt. Hood Resort (5,000 to 6,000 feet). High up, about 6,500 feet and higher, 20 to 30 inches will fall. If you're driving over the passes over the next two days, it's likely to snow in the morning, but expect mostly slush or wet roads during midday and afternoon. The Santiam and Willamette passes are slightly higher, so the snow cover there will last longer each day.

NEXT WEEK MILDER AND DRYER

Another weak upper level trough will extend through Saturday, bringing lighter showers. Then we generally head for a gradient with ridges near or just offshore. This leads to weak weather systems or dry weather. You can see the higher-than-average highs next week in this 7-day Euro ensemble average

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