Where is Summer? A Look Ahead After Coolest July Start in 10 Years

July 7, 2020

8:30pm Tuesday…

It has begun…complaints about cool summer weather. I often get complaints this time of year, some people expecting that we should have Sacramento style heat in Portland. To be fair, the past two days have been especially cloudy and cool. Today was the 2nd day in Portland without seeing a 70 degree temperature; our typical high this time of year is 78-79 degrees!

We’re now approaching two weeks of below average temps.

The average high temperature for this first week of July is the coldest since 2000! My little butternut squash and cucumber plants are struggling…just a few inches high. Too little sun and most days only in the 60s up in the hills. At least we haven’t seen much rain the past 2+ weeks; it’s very clear our dry season has arrived.

So, the big question…

IS THIS IT?

WHAT WE ARE SEEING NOW…IS THIS OUR “SUMMER” THIS YEAR?

The short answer; it’s unlikely this same cool weather pattern continues the next 9 weeks to Labor Day. But there is no sign of hot weather in the next 7-10 days either.

First, we are overdue for an average or cool summer west of the Cascades. I’m not saying that’s about to happen, but the past six years have featured an unprecedented string of warm to hot summers in the Portland metro area. 2016 wasn’t crazy warm and neither was last year. In fact much of the warmth last year was due to excessively warm nights; a consequence of warmer than normal ocean water offshore.

My point in bringing this up is that, at some point, we should expect to get a cool summer.

The weather pattern the past two weeks has featured a setup like this in the upper-atmosphere; weak “troughing” or a dip in the westerly flow over the Pacific Northwest. High pressure (and warmer air) has been suppressed to the south and east regularly. Notice most of the country is very warm to hot! We are all alone in the cool weather out here

A warm/hot July weather setup looks more like this; the westerly flow pushed farther north into Canada. That takes much of the cloud cover and showers north as well = sunnier and warmer weather west of the Cascades

Looking ahead, that upper-level trough backs off a bit the rest of this week. The result is more sunshine and warmer days. By Saturday that hot upper-level ridge is much closer to us. At this point it appears this should finally be a setup for a sunny Saturday and temperatures in the 80s.

But by Monday another system is passing by to the north, once again bringing a surge of cool marine air inland Sunday and maybe even a shower. A continuing issue the past couple of weeks is models only catching onto these cold troughs about a week ahead of time. A week ago it appeared we’d be heading into a very warm summer pattern this coming weekend. Instead that is being delayed once again by this system Sunday/Monday

Looking farther ahead, we should warm again a week from now as high pressure builds just offshore. This is the GFS model for next Wednesday the 15th

The morning ECMWF model’s forecast for high temps in Portland shows this trend as well.

Warming through this Saturday, then cooler, then warming again a week from now. You can add about 5 degrees to most of these to get a Portland high temperature. In general this is a bit warmer than what we’ve seen the past two weeks. It would imply the next 10 days will be near average for mid-July.

No model shows a wet weather pattern ahead, just a few drips here and there. ECMWF says less than .20″ in the Willamette Valley through the next two weeks. As mentioned earlier, the dry season is here:

It’s summer and vacation time, so I’ll be off until Sunday. Enjoy the warmer late-week temps!

Chief Meteorologist Mark Nelsen