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.

They Say “April Showers Bring May Flowers”… So Where Are The Showers?

The majority of this month has been quite pleasant weather-wise. The sun and dry weather has served as a mood-booster for so many people in the midst of the COVID-19 pandemic. But it still begs the question…where is the rain?

Here is the Paine Field precipitation accumulation graph so far for the month of April.

Figure 1: Accumulated precipitation for KPAE, via NOAA

With the exception of some trace rainfall on April 11, all the rainfall has occurred in the first few days of the month, amounting to just 0.35 inches. The normal amount for this period is 1.48 inches.

When looking at the same graphic for Sea-Tac, we get a similar story.

Figure 2: Accumulated precipitation for KSEA, via NOAA

Except here, there has only been 0.01 inches of accumulated rainfall. You can hardly even see the green line on the graphic.

To put this into perspective, take a look at this tweet.

Much of California has been getting hammered by storms and rainfall and has significantly more than us here in western Washington. Even areas of Arizona have more than Sea-Tac! Wow.

So why has our weather been so nice recently? It has been the result of a ridge of high pressure that has been acting as a block, preventing storms from making it to our region. (You can read more about this in Cliff Mass’ blog, found here.)

And, spoiler alert, this nice weather is likely to continue through the rest of the week.

Highs today should be in the mid-to-upper 60s for most of us.

Overnight tonight, clouds begin to increase as onshore flow (i.e. from west to east) develops. As a result, Wednesday morning has a chance to start cloudy. But as the figure shows below, clouds should burn off by the afternoon. Because of the cloudy start, Wednesday’s highs could be slightly lower than today’s.

Figure 3: Cloud cover percentage (darks = less clouds, lights = more clouds)

Thursday and Friday look to be the warmest and nicest days of the week, with highs in the low 70s possible!

Figure 4: GFS high/low temperatures for KPAE
Figure 5: GFS high/low temperatures for KSEA

It should be perfect to go outside and go on bike rides, walks, and the like… of course maintaining social distancing 🙂

Some models/ensemble members of models show a chance for light showers on Saturday, but if anything falls, it likely won’t amount to much. Models are also suggesting the chance of some rainier weather next week, but it’s too far in advance to know for sure.

In the meantime, enjoy the sunny weather!

Sunny and Dry This Week… But Please Stay Home

This week, for the first time in forever (or so it seems), it should be dry and the sun should be out at times for much of Western Washington. But that doesn’t mean you should be going out to public parks and beaches to enjoy it.

The last time it got super nice, people flocked to parks and beaches, hardly taking any consideration for social distancing. Exhibit A:

Figure 1: Tweet originally found here

Please, for the sake of those around you (especially the most vulnerable), don’t do this. If you go outdoors, do not congregate in places with a lot of people (yes, that includes certain hiking trails). Try to stick with walks and bike rides around the neighborhood, always maintaining distance from others.

Okay, rant over (sorry about that).

It will be tempting at times to want to go out to these public places, though. Take a look at the daily temperatures at Paine Field in Everett according to the GFS (i.e. American) ensemble.

Figure 2: Temperature GFS Ensemble for KPAE

Much of the week will see highs in the mid-to-upper 50s, while the low 60s are possible by the end of the week. For native Washingtonians like me, that is almost t-shirt weather. The European model doesn’t show temperatures quite as warm, but are still in the mid-to-upper 50s. Temperatures closer to Seattle and Sea-Tac look to be a touch warmer than Everett, as shown below.

Figure 3: Temperature GFS Ensemble for KSEA

Not only is it supposed to be warmer, but it’s also supposed to be dry. Take a look at this:

Figure 4: 24-Hour Precipitation GFS Ensemble for KPAE
Figure 5: 24-Hour Precipitation GFS Ensemble for KSEA

All of the above GFS ensemble members are not showing the chance of rain until Saturday… BUT, there’s still plenty of time for that to change in the coming days.

Even though it’ll be warmer and dry, it won’t be 100% sunny the whole week. Expect to see some cloudy to partly cloudy skies at times; but don’t worry–we should definitely see our fair share of sun. There will be plenty of opportunities to go outside for a walk or bike ride–again, keeping your distance from others!

This week, it’ll finally start to feel more like Spring after a stretch of below-normal temperatures. In this time of uncertainty, I know it will lift the moods of many people. Just like the sun always eventually comes out, even after the darkest of days, we will eventually get through this.

In the meantime, I hope you stay safe and healthy.