August 12, 2021

7:30pm Thursday…

You’ve just made it through ANOTHER 100 degree day in Portland. PDX hit 102 yesterday, and SO FAR has hit 103. That was the 6pm temperature. You see the entire metro area was in the 103-107 degree range. This would be our big summer heatwave…if it weren’t for the historic event back in late June that produced 108-116 temps at PDX. What a summer…

And the official numbers across the region

Off the map, a gusty northeasterly wind reached Bellingham, Washington today. That pushed the temperature to 100 degress…an all-time high! The airport there is located very close to the water so most afternoons a cooling onshore breeze keeps the extreme heat away. Not today; summer 2021 will be remembered for a long time all across the region. Notice a bit more onshore flow at the beaches = no heat there. A bit cooler than yesterday at Astoria and Tillamook.

For the hardcore weather geeks, I see the 850mb temperature on the afternoon balloon sounding over Salem was +25.8 degrees (C). That’s very near what used to be the all-time record…this is a hot airmass! There was about 1 millibar of easterly flow through the Gorge earlier today and some light easterly flow was blowing over the Cascades. That was just enough to warm us up a bit from yesterday. That easterly flow delivered a first batch of lowland wildfire smoke to the Portland metro area.

Here’s the current view from our Skyline Camera; not really a “postcard-perfect” moment in the Rose City is it? You can’t see more than about 15 miles; Troutdale and Gresham are out there…somewhere

Current AQI shows parts of metro area and Gorge into the “UNHEALTHY” category; not so bad up north at Longview and in the Willamette Valley.

I want to alleviate any renewed anxiety about us having another “SmokePocalypse” similar to last September

  1. There are no huge fires close by to produce massive volumes of smoke
  2. Flow goes westerly the next few afternoons = dense low level smoke shouldn’t get stuck in the valleys
  3. It’s not September, when it’s much easier to get inversions and smoke lingering
  4. Westerly flow returns at all levels of the atmosphere Sunday = much better later that day and next week

Check out the HRRR smoke modeling forecast. First, right now. Notice the colors (generally) match the Air Quality Index categories:

Then by tomorrow morning an even thicker surge of smoke has arrived at the eastern end of the Gorge. Really bad air Hood River, The Dalles, and farther east. But not much worse in Portland

Just in time, we switch to a light westerly flow tomorrow afternoon west of the Cascades. That pushes the thickest smoke over and east of the Cascades…at ground level. There will still be a sickly, yellowish sun overhead. Notice the model thinks the Tillamook forest fire will produce significant smoke; that seems unlikely.

By midday Saturday, a continuing (light) westerly flow is keeping most areas west of the Cascades in good shape, and west wind in the Gorge is helping a bit too. On Sunday I expect more westerly flow and even better conditions

Remember these are GROUND LEVEL forecasts, there will still be lots of smoke swirling overhead many thousands of feet up.

As for temperatures, the strong upper level ridge remains over us tomorrow and Saturday.

Then weakens with two cool upper-level troughs passing by both Sunday night and midday Tuesday. This returns us to a more typical morning clouds and afternoon sun routine. High temps drop back to around 80…much better!

By the way, Portland only dropped to 70 degrees this morning, which makes it an ALL-TIME RECORD WARM NIGHT FOR THE MONTH OF AUGUST. Salem now has a new record for the month too… at 69 degrees. The days of “you don’t need air conditioning in Portland” are over aren’t they? Take a look at this. The number of nights at/above 60 degrees at PDX for each decade.

Wow! What a change the past 10 years…of course in general a warming urban area is going to see warmer nights as the decades go on. But the past 10 years have been amazingly warm. Here’s the deal, clearly a large part of this IS the urban heat island. But some is our warming climate as well. I checked Salem, Eugene, Olympia (using both 60 and 65 as a cutoff) and can’t find a similar effect. Yes, nights are warming, but nothing so dramatic as what we’re seeing in Portland.

That’s it for now, I’ll be on at 8pm & 9pm (PDX-TV), and 10/11pm (KPTV). I’ll see you there.

Chief Meteorologist Mark Nelsen

Hottest Summer On Record Produces Another Heat Wave This Week

August 9, 2021

8pm Monday…

I was on vacation last week and part of the previous week, but back in the forecasting saddle this week. What has changed? It’s been hot, except for a brief cool down Friday-Sunday. And a “big” .03″ rain fell at PDX, ending our 51 day dry spell

Yesterday our own Jeff Forgeron (meteorologist on Good Day Oregon) married his best friend of 13 years under comfortable temperatures, low humidity, mainly sunny skies, and no smoke. A perfect afternoon for a “weather” wedding; Jeff nailed the timing, avoiding all the weather issues. Congrats Jeff & Katie! Here’s a nice pic of the weather team from Brian; the best team we’ve ever had!


I’ve just gone through the numbers, which are stunning:

  • #1 hottest summer on record at Portland, Salem, Eugene, Medford, Redmond, & Pendleton

This includes June 1st through August 8th. IF we have a cool 2nd half of August, that could knock us out of 1st place. For many stations, the previous “hottest summer” was 2015. Redmond’s previous hottest was 1968. Notice this includes BOTH stations where we’ve seen urban heating and others with little/no land change around the stations. This isn’t just about growing urban areas turning warmer (Example: Portland airport). We are living through a historically hot summer.


  • Portland’s 5 hottest summers? All recent (in order too): 2021, 2015, 2018, 2017, 2009
  • Salem has a longer record that goes back to 1893. Hottest years are the same: 2021, 2015, 2018, 2017, 2009
  • Salem has seen 31 days at/above 90 so far; by Friday the new record should be 35 days there.
  • Pendleton is a bit different. The 5 hottest: 2021, 1967, 1961, 1958, 2015


Portland has only seen 3.80″ rain since March 1st. That’s 5.5 months! If that happened every year, we wouldn’t have green trees all around us. That tells you all our vegetation is very stressed, and of course fire danger is extreme throughout the region. This is the driest we’ve ever seen during this period. BUT, down at Salem, over 6″ has fallen. Still well below normal, but “just” 10th driest. Pendleton has only seen 1.34″ during this time = driest on record like Portland.


Here we go again, just like in June (but not as intense); a strong upper-level ridge is developing just offshore. That means a dome of very warm air. Here’s the forecast for tomorrow; a 598dm ridge is highly unusual (again) at this latitude

Then by Thursday it flops in over on top of the Pacific Northwest. At this point 594dm heights cover much of the region. This is major heatwave territory from June through mid-August.

Now this model (WRF-GFS) quickly pushes a much cooler trough overhead Saturday and Sunday for dramatic cooling. Others keep the heat through Saturday; I think that’s a more likely outcome. Temperatures are forecast to peak around +25 to +27 (Celsius) Wednesday through Friday afternoons at 850mb. This is also major heatwave territory. Remember (until late June this year), the all-time high 850mb temp was +28.2. We will be close Thursday and Friday.

This will not be a heatwave with gusty easterly wind through the Gorge or into the western lowlands or OR/WA. That means two things. First, we won’t get as hot as we might get with a gusty east wind (106-108). And the coastline will remain reasonable, no hot east wind out there. Most likely even the north coast remains at/below 85 degrees this time around. You can see the weak/flat “thermal trough” straddling the western valleys and Cascades Thursday afternoon. This means no onshore cooling breezes, but no east wind either.

With all this in mind, we’re going for three days at/above 100 degrees Wednesday-Friday.

In reality, we could end up with just (1) 100 degree day. Why? First, Wednesday we might end up at “just” 98-99. Second, fire smoke is a big issue the 2nd half of the week. Even just a moderate smoke layer overhead could easily keep us in the 90s Friday. NASA’s GEOS-5 smoke modeling shows lots of smoke over the region Friday afternoon/evening

There are numerous small/moderate size fires burning in several complexes on the west slopes of the Cascades. We can assume they will burn more vigorously this week with heat and instability. As the upper-level ridge moves over/east of us Friday, that opens up southerly flow, bringing smoke north. Here’s the view this evening:

That’s it for now; I’ll be working most of this week. Make sure you follow me on Facebook and Twitter for more frequent updates there: Twitter: @marknelsenKPTV and Facebook @marknelsenweather

Chief Meteorologist Mark Nelsen

A Warm July Ends With A Heatwave

July 26, 2021

9:00pm Monday…

It’s vacation season in the Pacific Northwest; the best weather of the year! So I’ll be joining many of you travelling across the region the next week and a half. Heading out for camping in parts of southern Oregon. No posts during that time, unless something really serious pops up (major fire close to us, huge earthquake, volcanic eruption, tsunami, etc…). I’ll be back at work Sunday August 8th.

The end of July is quickly approaching and it’s been a warm month! No record-breaking heat, or heatwaves, but consistently warmer than normal. It appears we’ll end up with at least the 5th warmest July on record, likely #3 or #4.

The western 1/3 of the USA has been sizzling so far this month, following the warmest June on record for some.

We’ve been “lucky” west of the Cascades, picking up just enough cooling onshore flow to keep us near/below 90 degrees most of the month. Portland has seen (12) 90 degree days so far this year

Yet, just slightly farther removed from that ocean air, both Salem and Eugene have seen over 20 days at/above 90!

Looking ahead, we have a heat wave on the way Wednesday-Saturday. This is what we’re thinking this evening for Portland:

No record highs, since they are generally 100+ this time of year. But four 90+ days to wrap up July.

Why is it turning hot again?

Strong high pressure bringing heat over the Rockies is far enough east to keep our temps reasonable again tomorrow. That “594” contour centered over Colorado is the center of the upper-high.

But you see it snuggles up a bit closer to us Friday and Saturday. Here’s midday Saturday; the ridge of high pressure has amplified, and southerly flow is in charge across the West Coast. This MAY bring thunderstorms north into the Cascades and Eastern Oregon. There are even a few GFS and ECMWF ensemble members sending a disturbance north with showers/thunderstorms WEST of the Cascades this weekend. But not enough to put it in the forecast. Just be aware that this weekend is not “guaranteed” dry. Keep an eye on the forecast.

This pattern doesn’t produce a hot easterly wind over the Portland area (ridge is too far east), which should keep us below 100 degrees…but just barely! Then Sunday and beyond the ridge weakens; we’re back to reasonably warm temperatures for the first few days of August. This is Tuesday (August 3rd)

By the way, we are at day #41 without rain in Portland. The last MEASURABLE rain was June 15th. There WAS a trace at PDX on July 1st. Assuming we don’t get rain in the next 12 days (possible), we’ll be up in the “top 5” range for dry spells. But for now we’re a long way from that 71 dry day record

A few more notes:

  1. I don’t expect high humidity during the upcoming heat wave, UNLESS we get some showers or thundershowers Saturday/Sunday.
  2. Overnight temperatures will be turning very warm, mid-upper 60s. This isn’t as extreme as the historic heatwave back in June, but it’s still worth checking in on elderly friends/relatives.
  3. Southerly flow = overhead fire smoke from California fires. Expect increasing haze and yellow/orange sun after Wednesday. Low-level smoke is UNLIKELY west of the Cascades since wind will be coming from the northwest and west.

Stay safe during summer vacation travels!

Chief Meteorologist Mark Nelsen

Warm & Dry July Continues, Plus Some Good Fire News

July 21, 2021

8pm Wednesday…

We’ve been in a surprisingly stable weather pattern ever since the heat wave ended in late June. Warmer than normal, but not much heat. We are three weeks into July; every day has ended up between 75 and 90 in Portland. Today was especially nice with partly cloudy conditions all day long. We’ve seen lots of days in the mid-upper 80s in Portland, but only hit 90 once (on the 6th). That’s due to a persistent weak onshore flow; that cooler ocean air pouring inland each evening. It tends to come up the Columbia River to Longview and then the metro area. That’s different than the “southwest push” coming in over the Coast Range we saw right at the end of the heat wave.

Salem and Eugene, farther removed from those cool northwest breezes, have each seen 9 and 10 days above 90. That’s quite a difference! Although none of those days made it above 92 in Salem. Right now Salem is seeing it’s 4th warmest July on record; due to consistently warm temperatures vs. a series of hot spells.

A very consistent upper-level pattern remains in place the rest of the month (if models are correct). Right now a hot ridge of high pressure is right over the Rockies. At the same time a weak trough is moving by to our north; thus the cooler weather the past two days, even up in the mountains.

By this weekend, the last full weekend of July, the high edges a bit closer. So we turn a bit warmer as onshore flow backs off again. We might even hit 90 in Portland…maybe.

Then the ridge moves farther away, back into the Great Plains early next week. 9 days from now, Friday the 30th shows us in the “Goldilocks Zone” west of the Cascades. Warm, but no heatwave and not much “hot” weather.

All models agree with this general setup the next 7-10 days.

What This Means

  1. Temperatures remain above normal, but a heat wave is unlikely through the end of July west of the Cascades
  2. Most fire smoke will continue to remain over/east of the Cascades. That southwest flow carries most of it well east of us. I don’t expect any sort of “smoke episode” in the Portland area the next 7-10 days
  3. A widespread outbreak of thunderstorms is very unlikely in this pattern, even east of the Cascades
  4. No chance for rain, guaranteed dry weather continues next 7-10 days

Speaking of rain, we’ve only seen a TRACE so far in Portland this month. It was a few spots of drizzle out of the marine layer on the 1st. A trace means it can’t be measured…less than 0.01″. July is our driest month of the year in Portland; we only average 0.50″! August is close behind at 0.54″. We almost never have a truly “wet” July. But I remember both 1983 and 1993 were showery and cool; quite rare indeed. Those were “green tomato” summers…


Fire season is off and running big-time this year. Numerous large (greater than 100 acre) fires have burned in both Oregon and Washington. This has been fueled by 3 years of drought in southern Oregon plus the driest spring on record for many areas. Then an unprecedented extreme heat wave baked the region in late June; a perfect setup for a bad fire season. At this moment there are 5 large fires burning in Oregon

There is one fire grabbing all the attention right now, the Bootleg Fire burning through the Fremont National Forest. That’s between Bly, Summer Lake, & Paisley

The Jack and Elbow Creek fires are large as well, but notice they aren’t growing quickly. Good news there. The Bootleg Fire is about to become Oregon’s 5th largest on record, passing up the Buzzard Complex

And I had better mention the “Tillamook Burn” because each time I show this graphic, someone accuses me of forgetting that one. Actually there were THREE large Tillamook Burns (and one smaller), beginning in 1933; it was called the “six year curse”. All in the north Coast Range between Banks and Tillamook.

The bad news, of course, is that we don’t have any cool/rainy weather systems headed into the region. We wouldn’t expect that in July anyway. Extremely dry fuels will remain that way until further notice.

The good news?

  1. We don’t see a real heatwave coming for the region over the next week or so.
  2. Lightning activity has been minimal to almost non-existent so far this season and will remain that way through the foreseeable future.

Considering the current very dry fuel conditions, IF we get a widespread outbreak of dry thunderstorms, then fire season could explode. Let’s hope that doesn’t happen. Typically that setup would involve a southerly or southeast flow in the upper-atmosphere. For now I’m not seeing that over the next 7-10 days.

That’s it for now; enjoy the near-perfect summertime weather west of the Cascades. Yes, a bit on the warm side, but no heatwave!

Chief Meteorologist Mark Nelsen

Cooler Late Week, Then Warmer; Dry Summer Pattern Here To Stay

July 12, 2021

9pm Tuesday…

In the past week we’ve seen warmer than normal temperatures persist west of the Cascades, although no real hot days in the metro area. Lots of 80s, before & after the marine push last Wednesday/Thursday. Yet just one day at 90 degrees.

Meanwhile Salem has seen 8 days at/above 90 so far this month. Why? We are in a classic “northwesterly flow” regime. The setup has been very stable for over a week. Wind is coming in off the Pacific each afternoon/evening to replace hot air rising over the interior of the Pacific Northwest. The Columbia River gap allows lots of that cooler marine air to come up through Longview, Kalama, Clark County, and into the Portland metro area. This morning’s satellite image (8am) shows enough cool air and moisture for low clouds in a good chunk of this area. Clouds tend to form central & eastern metro first because the marine air is bottled up against the the western Gorge. This is why west metro tends to be sunnier more often summer mornings than the east side.

Farther south, in the Willamette Valley, no morning clouds = warmer. The layer of cool air is thinner there. Look at the effect on high temperatures today. 77 at Longview to 90 at Salem.

Strong westerly wind through the Gorge keeps Hood River comfortable, but by the time you get to The Dalles the airmass has warmed. Way out in Hermiston, today is the 25th day at/above 90 degrees. They haven’t seen a cooler than average day since June 16th!

There are 4-5 significant fires burning across Oregon this evening. This is an amazing visible satellite image considering it’s only July 12th. You can see a new fire south of Detroit Lake (Bruler), Grandview fire NE of Sisters, Jack fire NW of Diamond Lake, and the massive Bootleg fire north of Bly

That Bootleg fire exploded in size Saturday, becoming a “mega-fire”. That’s a fire over 100,000 acres in size. It didn’t change much through this morning, then you can see it has exploded again this evening. I estimate a 25-30 mile long “fire-front” based on GOES-17 fire detection

Oregon has seen 22 megafires since 1980, most of them in the eastern half of the state. Of course 5 of those just occurred over/on the slopes of the Cascades last September. You can find a recap of that event here: https://fox12weather.wordpress.com/historic-september-2020-fires-labor-day-windstorm/

What’s Ahead?

  1. Dry weather continues across the region through at least the next 10-15 days.
  2. A cooldown arrives Wednesday and spreads east of the Cascades Thursday-Saturday
  3. Then we warm up again early next week
  4. There’s no sign of a heat wave west of the Cascades through at least the 20th

Check out the 500mb anomaly map (from the GEM model) for right now. In general we’ve got higher than normal (warm colors) heights overhead

By Friday, a cool trough is sitting just offshore. But notice heights have only come down to around normal for this time of year. The hot ridge has weakened and moved back to the “Four Corners” region. This pattern gives us widespread morning clouds west of the Cascades. High temperatures drop back into the 70s…a refreshing mid-summer weather pattern.

But by Monday the hot ridge is back, just to our east.

It’s still there NEXT Thursday, the 22nd, 10 days from now. This says above normal temps, but not extreme. Especially west of the Cascades.

You can probably guess there’s very little chance for rain in this pattern. No organized weather systems come close to us. Look at a bone-dry ECMWF model forecast the next two weeks: Just a spot of drizzle out of low clouds. Not a single one of 51 ensemble members produces even a tenth of an inch through the 27th!

Let’s hope for very little lightning and no human-caused fires. 3/4 of last year’s fires in the Pacific Northwest were started by people.

Enjoy the rest of the week! Chief Meteorologist Mark Nelsen

Stable & Warm Summer Weather Pattern Continues

July 5, 2021

11pm Monday…

A very brief post to let you know the weather has S-L-O-W-E-D down across the Pacific Northwest. Temperatures in Portland have hit 86 or 87 for the last 4 days! Not a lot of variation there.

We are in our summer dry spell with no significant rain in sight. There could be spots of drizzle west of the Cascades when the marine layer thickens Wednesday morning. Other than that, the ECMWF (GFS looks the same) ensembles show almost no chance of measurable rain the next two weeks. That’s through the 20th. ONE ensemble member out of 50 produces all of 0.10″ rain…

Just as unlikely through at least the middle of next week? A heatwave. No sign of that in the 15 day ensemble average, just the usual ups/downs as marine air surges in and out of valleys west of the Cascades.

That’s it for now.

There’s no need to worry about the lack of rain, there’s nothing you or I can do about it. So enjoy the reliable sunshine while it’s here. I’ll be off the rest of the week.

Chief Meteorologist Mark Nelsen

Marine Air Cools NW OR & SW WA; Drizzle Spots Thursday AM

June 30, 2021

9pm Wednesday…

That was quite a change today wasn’t it? For the first time in a couple weeks we totally busted the forecast. The marine layer was thicker than I expected…up around 4,000′ deep. That meant we never saw a total breakout into sunshine. Sure, a few sunbreaks here and there but that’s about it. After 14 days of 80+ weather, we finally saw a cooler day, only reaching 79 in Portland. That 14 consecutive day stretch was a new record for June in Portland; one of many records set this month.

June ends as the hottest on record, just edging out the very hot June 2015. Final monthly temperature is 70.7, August 2015 was 70.3. That month was consistently hot, but this year was more extreme for a shorter period. 9 days at/above 90 ties the all-time June record as well. The 30 year average for an ENTIRE summer is 14 in Portland

The marine layer thickens slightly tonight and by sunrise tomorrow the view from space should look like this afternoon’s view…all gray west of the Cascades.

There has been a lot of thunderstorm action over central/eastern Oregon this afternoon/evening. Very active and hopefully we don’t get a bunch of new/large fires going. The dry conditions, temperatures, and thunderstorms make it seem more like early August. It’s going to be a long summer.

Very sad news today from the heatwave; dozens of people have died. At least 45 in Multnomah county alone. I think it’s safe to assume more will be found alone in homes/apartments over the next few days. It really got me down for a few hours earlier in the day. My mother came over to our house for a couple nights Saturday-Monday, just in case the electricity went out at her assisted living facility. It didn’t and she was fine of course. But I keep thinking of people dying in their homes, especially the elderly…all alone with no friends or family to help. You might be surprised to find more people die from heat in the USA than any other weather event

In Oregon it’s a bit different, the #2 killer after taking the ocean into account. In general, weather doesn’t directly kill people very often here. If you take away the ocean-related deaths, less than 10 a year. That changed dramatically with this heat wave.

It’ll probably take some time to process all the temperature reports from the big heat wave. We know Hermiston officially reached 118 in Oregon Tuesday. The Dalles and Richland also hit 118 in Washington. The Dalles airport, where readings are taken, is in Washington.

But did some location hit 119, or 120, or 121? Most likely one of the cooperative observing stations in the two states did. We will see. Our local (Oregon) AMS chapter is hoping to plan a meeting just for this historic heat wave. Maybe in September.

We are in the summer dry spell now with no rain in sight, other than some marine drizzle Thursday morning. 12z ECWMWF 24hr QPF forecast shows 2 out of 51 members produced a tenth or two…in the next two weeks! That’s about the driest it gets

That’s it for now; I won’t be blogging as regularly over the next month or so…it’s summer vacation time.

Chief Meteorologist Mark Nelsen