Meteorological Summer is Over… But Summer-Like Weather Continues

Blue skies on full display from my yard 🙂 (9/1/20)

Although “traditional” or astronomical summer doesn’t end until September 22 (when fall begins), meteorological summer has officially ended. Meteorological summer spans the months of June through August.

Meteorological seasons were created to help aid in keeping consistent climatological data that could accurately be compared from year to year (there’s some variation in astronomical seasons). More can be read on this topic here.

Below is a snapshot of temperatures for the months of June through August. The highest temperature recorded for the summer at Paine Field occurred on August 16, with a temperature reaching 100 degrees! This was only the second time a triple-digit temperature has been recorded at Paine Field, with the first coming on July 29, 2009. August 16 was also when we had some thunderstorms in the area 🙂 ⛈ Two high temperature records were broken: June 23 with 77 degrees and August 16 with 100 degrees.

Figure 1: Temperature snapshot for meteorological summer at KPAE (2020)
Figure 2: Accumulated precipitation for June through August at KPAE

In terms of precipitation (shown above), we ended just slightly below average, with 3.55 inches compared to the average 4.05 inches. 2020 actually ended at number 10 in terms of the most precipitation during a meteorological summer! I’m not complaining ¯\_(ツ)_/¯

For fall lovers like me, the goal is in sight… but we aren’t quite there yet. We still have a stretch of summer-like weather to contend with.

Figure 3: GFS Ensemble temperature forecast for KPAE

The GFS ensemble members average near 80 degrees for the next several days at KPAE (ensemble averages tend to be more skillful than individual members). After that, it shows a spike in temperatures on Wednesday and Thursday of next week, with high temperatures in the mid-to-upper-80s. This still has time to change as it is still a ways away, but it’s worth keeping an eye on.

However, other models like the Euro do not go as warm as the GFS does. Take a peak at the Euro ensemble daily high/low temperature forecast:

Figure 4: Euro daily high/low temperature for KPAE

This still shows a spike in temperatures next Tuesday through Thursday, but not nearly as warm as the GFS.

But regardless of exactly how high temperatures get in the greater Everett area, it will still be warm. A ridge of high pressure setting up shop over the area will help contribute to the heat.

It is also possible that a thermal trough develops, which is responsible for most of our heat waves.

The great Cliff Mass describes this phenomenon in an old blog post found here. Here is an excerpt from it:

A lobe of high pressure extends inland of us, forcing offshore flow.   This offshore (easterly) flow starts over the heated interior of the continent and then gets even warmer when it sinks down the western slopes of the Cascades.   The result is that a tongue of warm air extends northwestward out of the southwest–generally northward from the interior valley of CA or the intermountain West—towards our region.   Each day it moves farther northward and strengthens.  And since warm air is less dense, a pressure trough (area of low pressure) extends northward with the warm air. 

As already mentioned, models disagree on exactly how warm it will get over the next several days. But I think it’s safe to say that it’ll still feel like summer for awhile–in terms of both temperature and dryness.

Figure 5: GFS ensemble for 24 hour precipitation at KPAE

None of the GFS ensemble members show a drop of rain until late next week, and even then, it’s a small amount. The Euro shows a mostly dry next several days, as well. Good news for those who never want summer to end. Take advantage of it while you can! It won’t last forever 😉

Has Summer Finally Arrived in Western Washington?

After what has seemed like a dreadful start to summer (at least to some), it seems like summer has finally started in the area.

Overall, since meteorological summer began in June, temperatures have been mostly in the 60s and low 70s, as illustrated in the figure below. In fact, at least at Paine Field, the temperature has not yet reached 80 degrees. On average, the first 80-degree day of the year is June 12—so we’re a little behind schedule! The last time it’s been at least this far into summer without an 80-degree day was 2012 (when the first 80 degree day occurred on August 4th)!

Figure 1: Daily temperature data from Paine Field Airport (KPAE) since June 1

In terms of precipitation at KPAE, we are actually slightly below the average accumulation of 2.53 inches since June 1st, with a total of 2.34 inches. However, when you look at the number of days with non-zero amounts of rain, it tells a different story. We are currently at 23 days of rain in the same time span.** And many of those days were on a weekend!

Figure 2: Number of days of rain at KPAE during the above time span

As you can see, this year ranks number 2 for the most amount of days of rain in the available data. So even though the rain didn’t amount to much, we’ve seen more days of rain than usual.

But now it seems like we’ve flipped a switch and summer has finally arrived. And for the most part, it looks like it’s here to stay for awhile.

Figure 3: Euro model of 24-hour rain for KPAE

The above figure shows that besides a small blip of rain expected on Friday, we are supposed to be primarily dry for most of the forecast period, which will no doubt make many people happy. Even some of the most stout rain lovers are ready to have a little bit of real summer-like weather. I’ll admit it’s been a little nice to go outside without worrying about getting rained on.

Thanks to a nice ridge of high pressure setting up shop in the area, temperatures for the rest of the week will be quite comfortable, primarily in the low-to-mid 70s in the Everett area…which is just right, in my opinion. Tomorrow (Wednesday) looks to be the warmest day of the week. Some areas in Western Washington could even reach the low 80s! Friday’s temperature should drop slightly associated with the weak system that looks to bring a bit of rain over the area.

According to most recent models, next week is when more of the heat could make its way back. There’s still time for things to change but it’s definitely something to keep in mind looking ahead.

In the meantime, enjoy the summer weather and get outside…safely of course! It looks like the warm and dry weather is here to stay for awhile.

**Note: one of the precipitation daily values is missing from the 2020 official data, but in combing over other sources of data, I believe it did rain on that day. That would put the number of days with precipitation at 24.