Over the weekend, temperatures climbed to the mid-80s in Portland, breaking decades-old records, according to the National Weather Service. The agency also said that high temperatures for this time of year are typically in the 60s for the region. A cold, dry front will bring a short-lived reprieve from the heat on Tuesday before temperatures rise once more later in the week. Smoke from nearby wildfires has also prompted the Oregon Department of Environmental Quality to issue an air advisory alert in effect through Friday. Joining us to discuss the record warm start to autumn is Colby Neuman, a meteorologist with the National Weather Service office in Portland.
Note: The following transcript was created by a computer and edited by a volunteer.
Dave Miller: Temperatures climbed into the mid-80s in Portland over the weekend, breaking decades old records according to the National Weather Service and more hot and dry weather is on the way meanwhile wildfire smoke has prompted the Oregon Department of Environmental Quality to issue an air advisory alert in effect through Friday evening. Colby Neuman joins us to discuss this record warm start to the fall. He is a meteorologist with the National Weather Service Office in Portland. Colby, welcome to the show.
Colby Neuman: Thank you.
Miller: Can you put the last few weeks in context for us? Just how unusual is this heat wave?
Neuman: The first 10 days of October ended up being the warmest on record for the Portland Airport and that’s since records began in 1940.
Miller: What’s causing this?
Neuman: We’ve had high pressure more or less all over the Pacific Northwest and really for a lot of the Western US that has been in place since the summer months and it just hasn’t budged. And it’s been lasting into the fall a lot longer than it usually does. Then we had some weak easterly winds sort of blowing across the Cascades and that helps to warm up Western Oregon and Western Washington. That’s sort of what led to a nice early period of October weather that we’ve had just with a lot of high temperatures in the 80s and then some in the 70s, too.
Miller: And it’s not just warm or hot, it’s also been really dry. How much precipitation have we seen?
Neuman: Here in early October we did get a trace of rain on October 4th, but basically it’s been more or less dry across almost all of the region. We did get just a tiny bit of rain in the Cascades last night, just in a few spots, but most areas stayed dry. It’s a dry start to October and it looks like that’ll probably continue for at least the next week.
Miller: What’s the norm in terms of precipitation for the beginning of fall?
Neuman: The first 10 days of October, we typically on average see around three-quarters of an inch of rain here. So basically getting no measurable rain or just to trace just a few drops is certainly well below average for the first 10 days of October.
Miller: We’re just at the very beginning of what normally is the rainy season in the northwest? Certainly in the west side of the Cascades. I know that a ton can change, but what does this dry start mean so far for snowpack, river levels and aquifers?
Neuman: There’s a lot of issues to unpack there. In the very short term, it’s not helping our situation. From a water supply standpoint for Western Oregon and Western Washington, it’s not actually that concerning just looking at reservoir levels and all of that really, it’s our wintertime snowpack and springtime rains that really drive those. But for folks who live east of the Cascades, this certainly is a bigger deal because they are already in such a deficit—they get so little rain to begin with–and they depend on it so when they have stretches of no rain, then it’s only exacerbating the issues that they’re experiencing with the ongoing drought.
Miller: And the dryness that we’ve experienced west of the Cascades, has this been the case throughout Oregon?
Neuman: Yes, it has been. For the last 10 days, basically, the state of Oregon has been more or less dry whether you’re west or east of the Cascades.
Miller: What has this weather meant for wildfires?
Neuman: Well, it certainly has extended our fire season much later into the fall than it usually lasts. Our fire season in most years, especially in the Cascades, is sometime in August and then goes into September. But usually at some point in September we get a really solid soaking rain that reduces fire danger so much that we can still maybe have a little bit of smoke and wildfires persisting, but they’re basically done for the season. However, that rain just never arrived this year up to this point. Usually by now we aren’t thinking about fires but we are thinking about rising rivers. And usually we get more gray days and people start complaining about the rain but that’s certainly not the case this year.
Miller: Not only have the fires not been put out, but there are new fires in the Gorge.
Neuman: Right. We have the Nakia Creek Fire near Larch Mountain, in Clark County, east of Vancouver, that just started over the weekend. And then there actually are a couple other fires in the South Cascades of Washington—the Kalama Fire and the Siouxon Fire–that are burning sort of south and east of Mount St. Helens. That’s pretty unusual for fires to be burning in that region in general and then certainly in October it’s really unusual. Usually if something’s going to happen there, it’s going to be late August, early September.
Miller: What has this weather meant in terms of fire fighting?
Neuman: For firefighting, it’s certainly prolonging the season for the firefighters to be out on the fire. The dry weather actually does allow them to do a lot of back burning and allows them to establish fire lines and sort of contain the fire. So you usually will start to see containment grow on these fires even with the dry weather. But it’s not the same necessarily as if we just went into our rainy season and it just started raining day after day. Sort of the worst case scenario for them is for them to get a tiny bit of rain where it just moistens up the vegetation enough that they can’t set these back burns. But then if we had another stretch of dry weather, the fire could then proceed and grow, but fortunately we’ve just had this dry weather so they’re doing back burns and building lines and sort of growing containment lines around things like the Cedar Creek Fire. But it would probably be better if we could just go straight into the rainy season and just start getting one storm after another at this point.
Miller: So that’s looking weeks or months in the future. What does the near-term forecast look like?
Neuman: Well, more or less, what we’ve had for the last week to 10 days is basically going to continue for the next week at least. Lots of high temperatures in the upper 70s and low 80s. We may see some valley fog and low clouds develop from time to time that will be a little slow to scatter out during the midday hours. It might take until midday, early afternoon for some of those low clouds and fog to burn off, but it’s going to be a pretty quiet weather pattern, especially quiet for mid October at this point. It’s not something that we usually see. It’s not too often that we have this extended of a dry stretch through the first couple of weeks of October.
Miller: I had read that this was projected or maybe still is projected to be the third La Niña year in a row. What does that mean?
Neuman: Yes, that’s correct. It’s looking like we are going to have another La Niña. So the last two winters, the ENSO (El Niño-Southern Oscillation) index has been tipped towards the La Niña scale, which is basically that the ocean temperature off of South America in the Equatorial Pacific have been below average the last couple of winters and that’s going to continue into this winter. Usually here in the Pacific Northwest, it tends to mean we have a slightly better shot for above-average precipitation, especially later in the winter and into the spring months. And then we have a slight hedge towards below average temperatures, too. But the odds of that are still just a very slight hedge and in reality pretty much any weather pattern over the course of the winter is still on the table in a La Niña scenario. So places like the Northern Rockies are more likely to get above-average snow and see colder than normal temperatures. Places down in California tend to end up dryer in most La Niñas than what they typically experience in just your average winter. And we’re sort of in between where we usually hedge towards the colder and wetter scenarios, but it’s far from a guarantee. And, I think basically time will have to tell on that.
Miller: Colby Neuman, thanks very much.
Neuman: Thank you.
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