PORTLAND, Ore. (KOIN) – We had some warm summer days and nights this July.
We topped 90 degrees six times in Portland, finishing the month in the top five with an average mean temperature of 73 degrees. Just down the road in Salem, they finished the month as the warmest July on record (73.3 degrees). They endured 16 days at or above 90 degrees for the month. That is the difference of just 45 miles or so, but the location of Portland versus Salem is quite substantial.
Portland is right at the confluence of two rivers and we have the channel of the Columbia River that allows for the movement of air and the cooler marine flow. It is still tough to imagine a city that close having 10 more days at 90 degrees or above than where we finished July in Portland.
No doubt the heat keeps coming as we move into our last full month of Summer! Temperatures are near 90 degrees Monday through Wednesday, but the weather headline changes later in the week. Check the top three topics of focus in the chart below. The first two are vague because they come with more than just temperature, the hot and cool days will be influenced by other variables. We will get to those in the forecast below, but know that we have a pattern shift coming and that may even bring in some measurable rain for Portland (fingers crossed).
The Climate Prediction Center (CPC) puts out a monthly outlook, providing a projection for the month. They release a temperature and precipitation outlook, which will give the general idea of what is to come (taking many variables into consideration). Like most of the summer, a large section of the United States is projected to be warmer than normal. A higher probability for the northern states, and the states of the northeast. The CPC does have a small section, around Texas, as likely to be cooler than normal. You can use the two graphics below to match up the text here.
As far as precipitation goes, they have Portland in an equal chance to be below, normal, or above this month. That means the weather pattern isn’t leaning towards any specific outcome. I actually take this as a sign of optimism for the Pacific Northwest (PNW). We’ve been so dry this year, that not having a clear sign of another month being below average is probably a good thing. We are not in the “drier than normal” section of the outlook, although we can certainly find ourselves in that situation again this month.
The weather story is more detailed than the weather headlines from the article above. This is more of what is going to happen around the region, but they are all tied into one larger picture.
The first three days of the week are going to be hot. We have a persistent ridge of high pressure that has yet fallen to the badgering of any other changes to the atmosphere. It is keeping hot summer days across the forecast area and extending south to the four corner region.
This heat is pairing with the monsoon season, creating bursts of heavy rain and thunderstorms scattered around the southwest and even into Oregon, Washington, and Idaho. The bullseye for thunderstorms for the next two days is going to be limited to central and eastern Oregon. Most of northern California should avoid the threat of lightning. Lastly, wildfire smoke continues to impact the forecast, creating a haze around the region.
We have a few days this week that are going to be very pleasant, but we also have a few days this week that are going to be stressed with heat. The weather story above only tells the next 72 hours, but deep into the forecast we have cooler air coming from the Gulf of Alaska and even the chance for rain.
However, if you cycle to the second graphic, you’ll see how the summer has panned out so far (going back to June 20, summer solstice). If everything goes to plan this week, we will see an increase in the 90s, 80s, and 70s by Friday. This is also a reminder that our average high temperature is going to start going down from this point on. We finish the month of August at around 80 degrees!
We are also in a window of a fire weather warning right now, as of mid-day. The fire weather warning stretches from the Cascades into central Oregon and then extends south into Lake County. This is the area that is likely to see thunderstorm development this afternoon.
The first part is going to be sprinkled with thunderstorm activity, but we can’t say for sure that it will continue through the month. With the early week pattern, we have thunderstorms sprouting up most afternoons before fizzling off late at night. An increase in lightning and gusty conditions today. The thunderstorms have been bringing moments of downpours, but the lightning is an ongoing issue. This is why the fire weather warning is in place today. I would expect something similar on Tuesday as well. August is still prime wildfire season, making it likely that we have more fire weather warnings in place through the summer.
If you really focus on the fire weather warning, you can see that the red zone does transition over the Cascades to the foothills of Marion, Linn, and Lane counties. These are vulnerable areas this afternoon, as thunderstorms develop. The potential energy graphic below is showing areas that may have a little more oomph when it comes to energy today. That energy doesn’t always translate to thunderstorms, but it will at least give an idea of some of the pockets across the state that may have more to offer for development. Thunderstorms in August are common for central and eastern Oregon. This is the time where dry lightning can be an issue. We don’t tend to receive many storms around Portland this time of the year, but it is also not unheard of. Although there is some energy forming around the foothills today, I wouldn’t expect any development today. We may have a few more clouds that show bubbly tops!