Historic Pacific Northwest Heatwave of 2021

[tamarack]

23 hours ago, Roger Smith said:

If you are making a list of singularities then the 2003 heat wave in Europe should be added, early August, longer duration than recent ones, large death toll from heat prostration in Paris. 

In historical terms, heat waves in 1911, 1944, 1948, 1953, 1966 are probably in the same league as more recent and better known cases (better known to younger weather weenies at any rate). 

Not all climate facts point to runaway warming. Toronto has broken 100F on twelve occasions, only one of them since 1953. The annual max for NYC peaked around the 1930s to 1950s and has only recently begun to approach the highest level it attained (running 30-year averages). 

I think AGW is real and plays a role, but we don't really understand what natural processes are at work in either an unmodified or modified climate, so a lot of this is speculation and guesswork, which tends to invite in a political spin factor since nature abhors a vacuum. But I think we have to be honest and say that we cannot be sure what interaction there might be between human modification and natural variability. And that can be taken any way you want, saying that does not make one a "denier" just a clarifier. The role of AGW could be less or it could be even greater. My main motivation in producing a raftload of climate studies is to try to find foundations for disentangling these signals. I would readily admit it is difficult work. 

That 100+ for Toronto looks similar (in shape, not precise years) to the local long-term, 1893 on, co-op in the W. Maine foothills.  Farmington has reached 100 or more 14 times.  Seven came 1893-97 and based on 3 other stations 30-40 miles distant I think their siting may have been problematic.  The co-op reached triples 5 times in 1911 including 4 within 8 July days, the period in which all 3 NNE states set their current hottest temps.  Since 1911 only 2, 100 on 6/29/1944 as CAR set its all time high of 96 (on 6/28. Farmington's 7 AM obs included the previous afternoon) and 101 on Hot Saturday 1975 (recorded as 8/3: again, 7 AM obs.)  They've topped 95 only once since then, 98 on6/20/1995, and haven't reached even 95 since Sept. 2002.

[raindancewx]

4 hours ago, skierinvermont said:

One correction, it's not 1/10,000 to hit 116 on any given summer day, it's 1 in 200,000 to hit it for the entire summer. That's on a 1951-1980 baseline. Or 1 in 15,000 summers on a current baseline. But the statistic being floated around isn't just for a particular day.

That's assuming a normal distribution of maximum annual temperatures. I think you were saying that maybe the odds of this are a little higher than we might think because extreme events might be more common in a place like Seattle than in Tucson, because in Seattle, the "perfect" pattern could blow Tucson air onto Seattle and somehow in 100 years of data the "perfect" pattern just never happend (and nothing close to it either). I think I agree with this  but I hadn't mentioned it yet. I think the more technical way of saying it is that we only have ~100 years of maximum annual temperature observations. That's only ~100 datapoints. To assume the distribution is normal, or that the distribution is well-sampled with a sample size of 100 is a significant assumption. Usually, a random sample is still enough to estimate the standard deviation accurately because even if in 100 years of data we never saw "the perfect pattern" we would have seen a near perfect pattern a few times. But maybe this is just an especially unique pattern and "near perfect" behaves very different from "perfect." Again, in other words maybe the distribution is not "normal."

Another thing is this datapoint alone will dramatically shift the distribution. If you use a 1951-1980 baseline, the sample size is only 30 datapoints, which is probably a lot more accurate than most people think mathematically, but it is on the small size to form a representative sample. 

The other way of doing it that would get us more data is to use daily temperatures. From that distribution using random sampling you could generate a distribution of annual maximum temperatures. Or you could calculate the probability of seeing 116 on any given day. I'm pretty confident though that you'd still find it to be roughly a 4 sigma event (1 in 30,000 summers) if not the 4.37 sigma Don provided (1 in 200,000 summers). For a daily temperature anomaly it's likely 5 or 6 sigma (1 in 50 million). You still are assuming normality which is usually a pretty safe assumption, but maybe this is the rare exception. 

This is all speculation though. In general, assumptions of normality and small sample sizes work a lot better than most people think. It's not perfect, but usually it's very very close. But maybe this kind of error is the difference between 1 in 200,000 and 1 in 100,000.

Either way, I think it's important to recognize that this was not a 1 in 10,000 event for any given day in Portland. This was a 1 in 200,000 year event for any given summer in Portland. Major major difference. On a 21st century baseline it was more like a 1 in 15,000 summers event. In other words, the shifting of the distribution (due to climate change) made it ~10-15x more likely.

 

One last way of putting this, I believe it was calculated that this event was a 1 in 1,000 year event for the entire planet. In other words, the probability of seeing anomalies like this anywhere on earth in a given year is 1 in 1,000. In 100+ years of data that would mean there's some small but not tiny chance of this happening.

I wasn't trying to argue that the specific +40 or +50 readings are not super rare. I think those are flukish and not normally distributed at all. In fact, I ran some of the figures for the NW and Canada in sites with 100+ years of records and they don't really pass some of the normality tests depending on what you're looking for. I can tell you locally, precipitation and snow are the same way, unless filtered by ENSO. So I'm not a big fan of that premise. My focus was more on the general +30 and +35 zone. I think with enough +30 events, you have to look at it as inevitable that some spot somewhere would greatly exceed the general trend. My math was my daily estimate for +35 odds, not +40 or +50. I do think it's well under 1 in 200,000 for a spot to hit +30 in a given day. It's not really that rare in the way we perceive time with so many days.

My assumption here is if the high was as strong, but 15 miles displaced in a parallel universe Earth but the same pattern existed, you'd have different sinking air through the valleys and then the sea breeze would behave differently too. You'd end up with a different collection of records by magnitude and space. That's why it's so dumb to me to attribute the +50 or the +40 to climate change. You should be trying to figure out if this setup exactly or with slightly different positioning is going to happen again, or if next time the high will be as strong, but with a sea breeze allowing Seattle to be 78 while Spokane is 110.  Most of the research I see is only about "proving" the Earth is warming to show the science is settled using poorly calculated probabilities, which is dumb, if you believe it is settled as the scientists surely do. I really don't have an issue with the general idea of warming, but the way the science is used in situations is borderline useless, since no one knows if this will happen later again this Summer or in 5,000 years, even if the odds favor it happening more.

[skierinvermont]

1 hour ago, raindancewx said:

I wasn't trying to argue that the specific +40 or +50 readings are not super rare. I think those are flukish and not normally distributed at all. In fact, I ran some of the figures for the NW and Canada in sites with 100+ years of records and they don't really pass some of the normality tests depending on what you're looking for. I can tell you locally, precipitation and snow are the same way, unless filtered by ENSO. So I'm not a big fan of that premise. My focus was more on the general +30 and +35 zone. I think with enough +30 events, you have to look at it as inevitable that some spot somewhere would greatly exceed the general trend. My math was my daily estimate for +35 odds, not +40 or +50. I do think it's well under 1 in 200,000 for a spot to hit +30 in a given day. It's not really that rare in the way we perceive time with so many days.

My assumption here is if the high was as strong, but 15 miles displaced in a parallel universe Earth but the same pattern existed, you'd have different sinking air through the valleys and then the sea breeze would behave differently too. You'd end up with a different collection of records by magnitude and space. That's why it's so dumb to me to attribute the +50 or the +40 to climate change. You should be trying to figure out if this setup exactly or with slightly different positioning is going to happen again, or if next time the high will be as strong, but with a sea breeze allowing Seattle to be 78 while Spokane is 110.  Most of the research I see is only about "proving" the Earth is warming to show the science is settled using poorly calculated probabilities, which is dumb, if you believe it is settled as the scientists surely do. I really don't have an issue with the general idea of warming, but the way the science is used in situations is borderline useless, since no one knows if this will happen later again this Summer or in 5,000 years, even if the odds favor it happening more.

I don't believe any of this is about "proving" climate change at all. The studies are specifically called attribution studies. They begin with the assumption that the earth has warmed x degrees, the Pacific NW has warmed y degrees, and that this warming is due to "climate change." You can never "prove" climate change because some rare event happened... yeah it would have been even less likely 50 years ago but it still *could* have happened. We don't need to prove "climate change." The climate *has* changed. The mean has shifted and the associated distribution of anomalies has shifted. Any graph of mean global temperatures, or record highs vs record lows will tell you this.

It's interesting to know that temperature distributions in the Pac NW are non-normal. However, even if the distribution is non-normal, it doesn't really matter in terms of attribution. Whatever the distribution is, when you shift it warmer by ~2F, any given extreme high temperature becomes ~10x more likely. You can't really say climate change "caused" this event, but you can say it made it roughly 10x more likely. 

I think you should read some of the attribution studies and get back to us with specific objections, I'd be happy to discuss them. I'm sure there are occasional statistical misinterpretations.

And as I said, if you assume normality this was a 1 in 200,000 summers event, not a 1 in 200,000 Portland June 28th event. I acknowledge the assumption of normality may be slightly incorrect. Maybe if you knew the true distribution it would be a 1 in 100,000 Portland summers event. Or 1 in 50,000 Portland summers. But it's not a 1 in 50,000 Portland June 28ths. It's much less common than that. Your point that there are lots of recording stations in the world besides Portland increases the global probability is completely valid. But your point that there are lots of days in the summer, or in the year, is not valid because the statistic already accounts for that. The probability that Portland would see a temperature on June 28th of 116 is likely less than 1 in a million (assuming the distribution is well-sampled after 100 years of data and is normal - assumptions which I agree may be somewhat erroneous).

Be careful not to confuse calcuations of attribution with calculations of recurrence. The assumption of normality matters a lot to calculating the recurrence probability (if the right tail is fat then it's going to be less than 1 in 200,000 recurrence). The assumption of normality matters a lot less to calculating the climate change attribution. No matter what the distribution is, shifting the distribution to the right by 2F will make any given point on the far right tail ~10x more likely. That's true regardless of whether the distribution is skewed or normal.

 

[raindancewx]

The attribution science assumes that some link between the Earth warming an extreme event can be found. But...it does it after it happens. To me that's like saying I studied that a big steak filled me up more than two slices of bread. I don't think it has any use. I know I complain about the math, but it's really more the philosophy that bugs me. You can predict after every single unusual weather event than a scientist will say it is Global Warming that contributed to the event. The public doesn't care because the public already knows the scientists will say that. People have no use for knowing that a specific unusual regional weather outcome in the future is linked to the Earth warming if there is no specific timeline for when it will or won't happen. The weather has always been pretty terrible at times, and people have always had to adapt to it, it's just now the adaptations are all toward the warming changes rather than more erratic changes.

You can't do anything useful behaviorally from knowing that a rare event was linked to changes in the Earth's temperature. Are people in Portland going to give up their cars? You might think they'd buy air conditioning, but you had a pretty big heat wave in the Northwest in July 2009 and even that didn't happen to a large extent, and it's not like the population stopped growing out there in the 1800s when they had prior less intense heat waves before cooling systems and things like cold bottled water were available. I don't see the point of any of it. If you're talking about something like water in the West, most of the states have had 10 to 100x increased population compared to 100 or 200 years ago, so even in a colder or wetter climate you'd have water and other resource shortages with poor planning. You would have had to divert water resources anyway out here just from the order of magnitude in the population growth (New Mexico went from 327,000 in 1910 around statehood to 2,100,000 now as an example, and even in the 1800s Mark Twain was noting the rivers rain dry, and most of the West has seen far faster growth).

https://www.carbonbrief.org/mapped-how-climate-change-affects-extreme-weather-around-the-world

[skierinvermont]

1 hour ago, tamarack said:

That 100+ for Toronto looks similar (in shape, not precise years) to the local long-term, 1893 on, co-op in the W. Maine foothills.  Farmington has reached 100 or more 14 times.  Seven came 1893-97 and based on 3 other stations 30-40 miles distant I think their siting may have been problematic.  The co-op reached triples 5 times in 1911 including 4 within 8 July days, the period in which all 3 NNE states set their current hottest temps.  Since 1911 only 2, 100 on 6/29/1944 as CAR set its all time high of 96 (on 6/28. Farmington's 7 AM obs included the previous afternoon) and 101 on Hot Saturday 1975 (recorded as 8/3: again, 7 AM obs.)  They've topped 95 only once since then, 98 on6/20/1995, and haven't reached even 95 since Sept. 2002.

Is it possible there was much less forestation back then? I know in CT basically 100% of the forest is new growth and you stumble along farming walls in the woods.

[skierinvermont]

21 minutes ago, raindancewx said:

The attribution science assumes that some link between the Earth warming an extreme event can be found. But...it does it after it happens. To me that's like saying I studied that a big steak filled me up more than two slices of bread. I don't think it has any use. I know I complain about the math, but it's really more the philosophy that bugs me. You can predict after every single unusual weather event than a scientist will say it is Global Warming that contributed to the event. The public doesn't care because the public already knows the scientists will say that. People have no use for knowing that a specific unusual regional weather outcome in the future is linked to the Earth warming if there is no specific timeline for when it will or won't happen. The weather has always been pretty terrible at times, and people have always had to adapt to it, it's just now the adaptations are all toward the warming changes rather than more erratic changes.

You can't do anything useful behaviorally from knowing that a rare event was linked to changes in the Earth's temperature. Are people in Portland going to give up their cars? You might think they'd buy air conditioning, but you had a pretty big heat wave in the Northwest in July 2009 and even that didn't happen to a large extent, and it's not like the population stopped growing out there in the 1800s when they had prior less intense heat waves before cooling systems and things like cold bottled water were available. I don't see the point of any of it. If you're talking about something like water in the West, most of the states have had 10 to 100x increased population compared to 100 or 200 years ago, so even in a colder or wetter climate you'd have water and other resource shortages with poor planning. You would have had to divert water resources anyway out here just from the order of magnitude in the population growth (New Mexico went from 327,000 in 1910 around statehood to 2,100,000 now as an example, and even in the 1800s Mark Twain was noting the rivers rain dry, and most of the West has seen far faster growth).

https://www.carbonbrief.org/mapped-how-climate-change-affects-extreme-weather-around-the-world

I mean I agree it's silly to care about these attribution studies simply because it's so obvious that global warming has contributed to every recent heat event. You're telling me that when the planet gets hotter it causes more heat waves? Obviously.

But you are way off base if you think knowing this very obvious fact is only useful if you can predict when and wear 10 years in the future an extreme heat wave will occur. That's kind of a silly and impossible standard, and even if you could predict weather 10 years from now down to the date, I'm not sure it would change much today at all. On the other hand knowing that the frequency of 95F days in Portland nearly doubled from 1950 to 2021 and will likely nearly double again by 2050 is useful information. It's useful for agriculture investors, energy investors, water planners, city planners, people considering where to move based on climate.

But it's probably most important to voters who might care about the overall environmental impact that will likely have on the pacific northwest rainforests, or how climate change will affect the economy and environment globally, and who might want to vote for representatives who will try to curb the ongoing and accelerating environmental catastrophe and accelerating human impacts via green energy subsidies and/or CO2 regulation.

 

If you were deciding where to move and wanted a nice climate, or were buying or investing in a farm (I know lots of small startup farmers), or were deciding where to invest in the electricity sector, would you care about knowing that Portland next hits 110F On July 9th 2032, or would you care that the frequency/probability of 95F and 100F days will increase 40% by 2035?

[LibertyBell]

7 hours ago, donsutherland1 said:

The Washington Post reported:

Within the next week, researchers expect to publish a “rapid attribution” study that determines how climate change made the Northwest heat wave more likely. Yet precisely quantifying the role of climate change in the event has been difficult because the heat was just so extreme, said Michael Wehner, a climate scientist at Lawrence Berkeley National Laboratory in California who is contributing to the attribution effort.

“It’s well beyond what straightforward statistical analysis would suggest. It’s well beyond what climate models suggest,” he continued. “But it happened.”

https://www.washingtonpost.com/climate-environment/2021/07/03/climate-change-heat-dome-death/

Here's a probability question- which was more rare the Pac NW extreme heat, or what happened in Siberia last year?

 

[donsutherland1]

45 minutes ago, LibertyBell said:

Here's a probability question- which was more rare the Pac NW extreme heat, or what happened in Siberia last year?

 

I don’t have daily records for Siberia, so I am not sure. This was a more intense episode of heat, but not as prolonged. Once the attribution study comes out, a comparison might be possible. In terms of intensity, though, this was the most severe outbreak of heat anywhere and at any time during the instrument record.

[Typhoon Tip]

They were both an example of synergistic feedbacks. 
 

 

[bluewave]

This was the warmest June on record from the Pacific Northwest across Canada to New England and the Canadian Maritimes. The most extreme heat was closest to the areas of the greatest 500 mb height long term height increases over Western North America. Those areas experienced all-time 500 mb heights near 600 dm. The secondary area of record warmth was located closer to New England where a June record 597 mb height was recorded at Upton, NY. This is the other region with fastest rising long term 500 mb heights east of New England. 

[LibertyBell]

21 minutes ago, bluewave said:

This was the warmest June on record from the Pacific Northwest across Canada to New England and the Canadian Maritimes. The most extreme heat was closest to the areas of the greatest 500 mb height long term height increases over Western North America. Those areas experienced all-time 500 mb heights near 600 dm. The secondary area of record warmth was located closer to New England where a June record 597 mb height was recorded at Upton, NY. This is the other region with fastest rising long term 500 mb heights east of New England. 

I was wondering if our heat was somehow related to that, because there was a heat spike more than what was expected.  100 at LGA and 103 at EWR were monthly records in their own right.

[LibertyBell]

8 hours ago, Typhoon Tip said:

They were both an example of synergistic feedbacks. 
 

 

Right, nothing occurs in "isolation"

 

[tamarack]

13 hours ago, skierinvermont said:

Is it possible there was much less forestation back then? I know in CT basically 100% of the forest is new growth and you stumble along farming walls in the woods.

That's likely part of the story, though Maine was never more than about 1/3 cleared and by 1970 was back up to 90% forest cover.  However, the current co-op site may be getting some influence from trees that are not as far from the instruments as they were 30 years ago.  (The critters keep growing, upward and sideways, the latter the potential culprit.)

[donsutherland1]

Weather summary
for British Columbia
issued by Environment Canada
at 11:26 p.m. PDT Saturday 3 July 2021.

Discussion.

The following area set a daily maximum temperature record on July 3, 
2021: 

Vernon Area (Vernon Auto) 
New record of 36.4 
Old record of 35.6 set in 1906 
Records in this area have been kept since 1900 

Note: the temperature record reported here has been derived from a 
selection of historical stations in this geographic area that were 
active during the period of record.

Please note that this summary may contain preliminary or unofficial 
information and does not constitute a complete or final report.

End/PSPC

[chubbs]

Saw this on twitter, the increase in severity of heat waves hasn't been evenly distributed. Much of the US has been spared the worst.

[bluewave]

2 hours ago, chubbs said:

Saw this on twitter, the increase in severity of heat waves hasn't been evenly distributed. Much of the US has been spared the worst.

Yeah, the corn has kept the Plains cooler than the East and West.
 

https://www.sciencemag.org/news/2018/02/america-s-corn-belt-making-its-own-weather

The United States’s Corn Belt is making its own weather

By Kimberly HickokFeb. 16, 2018 , 12:05 PM

The Great Plains of the central United States—the Corn Belt—is one of the most fertile regions on Earth, producing more than 10 billion bushels of corn each year. It’s also home to some mysterious weather: Whereas the rest of the world has warmed, the region’s summer temperatures have dropped as much as a full degree Celsius, and rainfall has increased up to 35%, the largest spike anywhere in the world. The culprit, according to a new study, isn’t greenhouse gas emissions or sea surface temperature—it’s the corn itself.

This is the first time anyone has examined regional climate change in the central United States by directly comparing the influence of greenhouse gas emissions to agriculture, says Nathan Mueller, an earth systems scientist at the University of California (UC), Irvine, who was not involved with this study. It’s important to understand how agricultural activity can have “surprisingly strong” impacts on climate change, he says.

The Corn Belt stretches from the panhandle of Texas up to North Dakota and east to Ohio. The amount of corn harvested in this region annually has increased by 400% since 1950, from 2 billion to 10 billion bushels. Iowa leads the country for the most corn produced per state.

To see whether this increase in crops has influenced the region’s unusual weather, researchers at the Massachusetts Institute of Technology in Cambridge used computers to model five different 30-year climate simulations, based on data from 1982 to 2011. First, they compared simulations with high levels of intense agriculture to control simulations with no agricultural influence. Unlike the real-life climate changes, the control simulations showed no change in temperature or rainfall. But 62% of the simulations with intense agriculture resulted in temperature and rainfall changes that mirror the observed changes, the team reports this week in Geophysical Research Letters.

Map of the central United States, showing changes in rainfall during the last third of the 20th century. Areas of increased rainfall are shown in green, with darker colors representing a greater increase.

MASSACHUSETTS INSTITUTE OF TECHNOLOGY 

The team then compared its results to historical global simulations from the World Climate Research Programme (WCRP), an international program for the coordination of global climate research sponsored by the International Council for Science, the World Meteorological Organization, and the Intergovernmental Oceanographic Commission of UNESCO. WCRP’s models take into account greenhouse gas emissions and other natural and humanmade influences, but do not consider agricultural land use. When researchers ran the numbers for the Corn Belt, the global models fell short of reality: They predicted both temperature and humidity to increase slightly, and rainfall to increase by up to 4%—none of which matches the observed changes.

Other climate simulations that use sea surface temperature variation didn’t match observed changes, either. Those simulations matched historical data until 1970; after that, the simulations predicted temperatures to keep increasing, rather than decreasing as they did in reality. This is a strong indication that agriculture, and not changing sea surface temperature, caused the regional changes in climate during the last third of the 20th century, the researchers say.

“The [influence] of agriculture intensification is really an independent problem from greenhouse gas emissions,” says Ross Alter, lead author of the study and now a meteorologist with the U.S. Army Corps of Engineers in Hanover, New Hampshire. In fact, Alter says, heavy agriculture likely counteracted rising temperatures regionally that might have otherwise resulted from increasing greenhouse gas emissions. One other place that shows a similar drop in temperatures, he notes, is eastern China, where intensive agriculture is widespread.

But how does agriculture cause increased rainfall and decreased temperatures? The team suspects it has to do with photosynthesis, which leads to more water vapor in the air. When a plant’s pores, called stomata, open to allow carbon dioxide to enter, they simultaneously allow water to escape. This increases the amount of water going into the atmosphere and returning as rainfall. The cycle may continue as that rainwater eventually moves back into the atmosphere and causes more rainfall downwind from the original agricultural area.

Rong Fu, a climate scientist at UC Los Angeles, agrees with the team’s assessment. She also thinks that though human influence might be “greater than we realize,” this regional climate change is probably caused by many factors, including increased irrigation in the region.

“This squares with a lot of other evidence,” says Peter Huybers, a climate scientist at Harvard University, who calls the new study convincing. But he warns that such benefits may not last if greenhouse gas emissions eventually overpower the mitigating effect of agriculture.

Alter agrees, and says it’s unlikely that the large increases in U.S. crop production during the 20th century will continue. Other scientists have voiced concern that agricultural production could soon be reaching its limit in many parts of the world. 

“Food production is arguably what we’re more concerned about with climate change,” Mueller says. And understanding how agriculture and climate will continue to affect one another is crucial for developing projections for both climate and agricultural yields. “It’s not just greenhouse gasses that we need to be thinking about.” 

 

[Hoosier]

We talk about the corn every so often in the Lakes/OV sub.  Where the impact of that really shows up is in the frequency of high end max temps... say 100+.  It has become increasingly difficult to get those temps. 

If there is one area of the country where the all-time highest state temperatures are probably going to be fairly safe for a while, it would be the Midwest.  Most of those all-time state records were set in the 1930s.  There were some isolated areas of the Ohio Valley that flirted with 110 degrees in the drought summer of 2012, but it took the worst drought since the Dust Bowl in those areas to do it and those readings are still generally several degrees short of the all-time state records.

[TimB]

4 hours ago, Hoosier said:

We talk about the corn every so often in the Lakes/OV sub.  Where the impact of that really shows up is in the frequency of high end max temps... say 100+.  It has become increasingly difficult to get those temps. 

If there is one area of the country where the all-time highest state temperatures are probably going to be fairly safe for a while, it would be the Midwest.  Most of those all-time state records were set in the 1930s.  There were some isolated areas of the Ohio Valley that flirted with 110 degrees in the drought summer of 2012, but it took the worst drought since the Dust Bowl in those areas to do it and those readings are still generally several degrees short of the all-time state records.

The interesting part of that is this: South Dakota is the only state that could be considered the Midwest by any metric that has recorded its state record high this century. It is also, per that map in the previous post, the state that has the greatest proportion of area where the average summer temperatures have gone down over the past 50 years.

[donsutherland1]

From the Boise NWS Office: Record streak of 70F low temperatures

https://twitter.com/NWSBoise/status/1412085747377606656?s=20

[TimB]

16 minutes ago, donsutherland1 said:

From the Boise NWS Office: Record streak of 70F low temperatures

https://twitter.com/NWSBoise/status/1412085747377606656?s=20

Good lord. I see each of the past 5 years and 6 of the last 7 on that list.

Edited to add: streaks of 3 or longer have occurred 34 times in Boise’s history according to the complete list. 21 of those 34 have occurred in the past 20 years. 13 of those 34 occurred in the previous 125 years on record.

In layman’s terms, something that used to happen once a decade is now happening once a year.

[LibertyBell]

4 hours ago, Hoosier said:

We talk about the corn every so often in the Lakes/OV sub.  Where the impact of that really shows up is in the frequency of high end max temps... say 100+.  It has become increasingly difficult to get those temps. 

If there is one area of the country where the all-time highest state temperatures are probably going to be fairly safe for a while, it would be the Midwest.  Most of those all-time state records were set in the 1930s.  There were some isolated areas of the Ohio Valley that flirted with 110 degrees in the drought summer of 2012, but it took the worst drought since the Dust Bowl in those areas to do it and those readings are still generally several degrees short of the all-time state records.

I wonder how much that big derecho took down?  I heard damage was in the billions.  Also, I read that many farmers are going out of business because of more frequent flooding and 3"+ rainfall events, so the corn business out there may be on the clock.....

I dont think thats sustainable farming anyway, monocultural farming is bad for the soil.

 

[donsutherland1]

11 minutes ago, TimB84 said:

Good lord. I see each of the past 5 years and 6 of the last 7 on that list.

Edited to add: streaks of 3 or longer have occurred 34 times in Boise’s history according to the complete list. 21 of those 34 have occurred in the past 20 years. 13 of those 34 occurred in the previous 125 years on record.

There has been a large increase in the number of such minimum temperatures:

1961-90: 2.3 days per year
1971-00: 2.6 days per year
1981-10: 4.0 days per year
1991-20: 6.1 days per year

2021: 8 days (through July 4)

10 Highest Annual Figures:
15, 2015
12, 2014
11, 2007, 2012, 2013
10, 2017
9, 1971, 1994, 2018
8, 1998, 2021*

[TimB]

36 minutes ago, donsutherland1 said:

There has been a large increase in the number of such minimum temperatures:

1961-90: 2.3 days per year
1971-00: 2.6 days per year
1981-10: 4.0 days per year
1991-20: 6.1 days per year

2021: 8 days (through July 4)

10 Highest Annual Figures:
15, 2015
12, 2014
11, 2007, 2012, 2013
10, 2017
9, 1971, 1994, 2018
8, 1998, 2021*

This is unfortunately a statistic that the AGW deniers would use their standard “but UHI” argument on, and ignore the fact that these 3 day streaks of lows in the 70s are 10 times as common as they used to be and that Boise is a relatively small city where UHI wouldn’t be nearly as pronounced as, say, PHX or MSP.

One other fact that should be included: I’m not familiar with Boise, nor have I ever been within 250 miles of it, but it would appear from looking at a map that the airport sits literally right at the edge of the developed area, so that would also mitigate UHI to some extent.

[Hoosier]

55 minutes ago, TimB84 said:

The interesting part of that is this: South Dakota is the only state that could be considered the Midwest by any metric that has recorded its state record high this century. It is also, per that map in the previous post, the state that has the greatest proportion of area where the average summer temperatures have gone down over the past 50 years.

I looked up that South Dakota record.  Looks like it happened in the central part of the state, which is toward the western fringe of the corn belt.  I don't know about the synoptics of that day, but it's probably safe to assume there were downsloping winds on that day for it to get so hot. 

[Hoosier]

50 minutes ago, LibertyBell said:

I wonder how much that big derecho took down?  I heard damage was in the billions.  Also, I read that many farmers are going out of business because of more frequent flooding and 3"+ rainfall events, so the corn business out there may be on the clock.....

I dont think thats sustainable farming anyway, monocultural farming is bad for the soil.

 

The derecho caused huge losses.  The before/after satellite images of the crop destruction were pretty stunning.  That derecho was on August 10, so basically too late for the crop loss to have any feedback on summer temps.  

[Roger Smith]

By the way it was the fourth warmest June on record at Toronto (downtown) at 21.4 C but short of 2005 (22.8) 1919 (22.5), 1949 (22.4) and even before urban heat island adjustments which would have moved 1919 about 0.4 lower, 1949 0.7 and the other two 1.1 C lower. June 1991 was 0.1 cooler in fifth place. The differentials were such that 2021 also took fourth place after adjustments, most of the 5-10 ranked Junes are fairly recent so none of them had much of an advantage to use by these adjustments. 

Report from the heat zone -- around Friday it began to moderate slightly each day but has remained very warm indeed for this climate, 35 C highs on the weekend. Somewhat cooler air pushed in just to our north so we went up that way and spent most of the weekend enjoying 28 C and scattered thunderstorms. As of time of writing it has not rained here at all but we have some activity moving in from the west on the radar, expecting a bit of thunder and maybe 0.25" rainfall. 

Fires not too big a problem locally, there was a stubborn one that while not very aggressive was hard to put out, west of Castlegar (on the outskirts of town) but it hasn't burned very far down the hill yet so no evacuations in the town, just on one outlying street near the fire. 

Otherwise in our drive around the region we could see smoke rising on the west side of the south arm of Kootenay Lake in an uninhabited area that is perhaps logged a little, from our perspective could not see much sign of clear cuts on the slopes. That was about ten miles west of the highway which runs up the east side of that lake. 

Not expecting much change in this current air mass which has become a bit more humid so the cooling does not feel like that much since the super heat was dry (dew points have come up from around 10 C to around 16 C). About 90% cloud cover today and 31 C. This is probably the coolest day here since June 20th. So we've now had a solid two weeks of either heat or extreme heat. Considering that our climate is statistically no warmer in summer than the east coast or the mid-Atlantic states, two weeks average of 98 to 100 F is quite something. 

[A-L-E-K]

18 hours ago, Hoosier said:

We talk about the corn every so often in the Lakes/OV sub.  Where the impact of that really shows up is in the frequency of high end max temps... say 100+.  It has become increasingly difficult to get those temps. 

If there is one area of the country where the all-time highest state temperatures are probably going to be fairly safe for a while, it would be the Midwest.  Most of those all-time state records were set in the 1930s.  There were some isolated areas of the Ohio Valley that flirted with 110 degrees in the drought summer of 2012, but it took the worst drought since the Dust Bowl in those areas to do it and those readings are still generally several degrees short of the all-time state records.

best climo

[bluewave]

 

The 99th percentile event, by definition, occurs 1 day in 100. Since there are 92 days in the Jun-Aug period, it is approximately a 1 year event. 2/

 

Because temperatures are recorded in whole degrees °F and the differences are typically in the small single digits, the map has a somewhat mottled appearance. 3/

 

If you remove "major" big city stations, the map looks almost identical and the gridded average only changes by 0.06°F. 4/

 

Finally, what about all that blue??? It's well understood that decades of land use and irrigation changes in the Great Plains has led to less extreme summer temperatures over the decades. This is, quite literally, a human induced change of the climate. 5/5

[Roger Smith]

Here's the record of daily highs at Warfield BC near my location. Warfield is a small town outside Trail BC, and the urban influence would be minor at most. It is also a few hundred feet above the Columbia River where Trail is located, so Trail likely had readings about 1 F or 0.5 C higher than these. I guess I was cooler by the same amount, not that it was all that obvious. 

For reference the normal late June and early July mean maximum temperatures in this location would be in the range of 28-29 C (83-84 F). I started the log from June 18 which was the first day after a mid-month relatively cool spell that broke 28 C. There were also three very hot days at the start of June (average 36 C). 

There has been zero rainfall in this now 19 day hot spell. In fact the last rainfall was 17 mm on June 15th. So today is the 21st consecutive dry day. This would not be all that unusual in late July or early August around here, but is quite unusual for this part of the summer season.

 I will post further data in this table until the heat wave ends. Today's values are estimates from hourlies so far. It is scorching hot and sunny again. 

 

Date ____ Max __ Min 

Jun 18 __ 30.6 __ 9.5

Jun 19 __ 29.1 __ 11.3

Jun 20 __ 29.7 __ 14.4

Jun 21 __ 33.4 __ 11.3

Jun 22 __ 35.3 __ 13.4

Jun 23 __ 34.2 __ 15.2

Jun 24 __ 32.4 __ 19.0

Jun 25 __ 35.7 __ 14.3

Jun 26 __ 39.6 __ 19.0

Jun 27 __ 42.3 __ 18.2

Jun 28 __ 42.5 __ 19.3

Jun 29 __ 43.9 __ 21.9

Jun 30 __ 44.8 __ 22.3

July 1 ___ 40.0 __ 20.7

July 2 ___ 37.2 __ 20.0

July 3 ___ 38.1 __ 19.0

July 4 ___ 37.2 __ 17.6

July 5 ___ 35.8 __ 17.3

July 6 ___ 37.1 __ 18.2 

19 day avg 36.8 (98.2 F) 

11 day avg 38.6 (101.5 F)

morning of July 7 overcast with spits of rain, trace amount so far.

this may be the end of the heat wave unless it clears up later.

__________________________________________________

If you read my tables of hottest NYC weeks, I would estimate that this location had probably seen values comparable to the top five in that once or twice in the past, perhaps up to around 100 F, but the value for average maximum June 26 to July 2 was 106.7 F which is about 8 deg (F) higher than any comparable period at NYC, and 0.7 higher than the all-time (one-day) high for NYC in July 1936. 

The saving grace is that we saw low humidity through the heat wave and overnight lows while balmy for this climate were tolerable enough. 

 

[donsutherland1]

Attribution Study: Pacific Northwest Heat "Virtually Impossible" without Human-Induced Climate Change

Excerpts:

Using published peer-reviewed methods, we analysed how human-induced climate change affected the maximum temperatures in the region where most people have been affected by the heat (45–52 ºN, 119–123 ºW) including the cities of Seattle, Portland, and Vancouver (with well over 9 million people in their combined metropolitan areas)...

Based on observations and modeling, the occurrence of a heatwave with maximum daily temperatures (TXx) as observed in the area 45–52 ºN, 119–123 ºW, was virtually impossible without human-caused climate change...
There are two possible sources of this extreme jump in peak temperatures. The first is that this is a very low probability event, even in the current climate which already includes about 1.2°C of global warming — the statistical equivalent of really bad luck, albeit aggravated by climate change. The second option is that nonlinear interactions in the climate have substantially increased the probability of such extreme heat, much beyond the gradual increase in heat extremes that has been observed up to now. We need to investigate the second possibility further, although we note the climate models do not show it. All numbers below assume that the heatwave was a very low probability event that was not caused by new nonlinearities...

Also, this heatwave was about 2°C  hotter than it would have been if it had occurred at the beginning of the industrial revolution (when global mean temperatures were 1.2°C cooler than today).

Looking into the future, in a world with 2°C of global warming (0.8°C warmer than today which at current emission levels would be reached as early as the 2040s), this event would have been another degree hotter. An event like this – currently estimated to occur only once every 1000 years, would occur roughly every 5 to 10 years in that future world with 2°C of global warming.

https://www.worldweatherattribution.org/western-north-american-extreme-heat-virtually-impossible-without-human-caused-climate-change/

The full study can be found here.