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Historic Pacific Northwest Heatwave of 2021


donsutherland1
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Well technically our heat wave and dry spell ended yesterday with a few rather weak thundershowers and generally cloudy skies, holding our maximum down to the mid 20s C (24.2 at Warfield) and dropping a small amount of rain, about 3-5 mm at my location and just 0.8 mm at Warfield. But there has not been any real change in air mass so with sunny skies again today it feels like it's heading back to the low or mid 30s. 

There were numerous lightning strikes around the region but possibly heavier rainfalls near the core of these storms which tracked by to our north and south on several occasions. So there are no reports of new fire starts locally. Larger fires continue to rage in central BC however. 

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The graph, shown above, looks at temperature patterns observed in the Pacific Northwest over the last 70 years and applies what is known as Generalized Extreme Value (GEV) theory to it. The fit, shown in red, looks pretty reasonable. 2/

One of the features of GEV is that it sometimes predicts that a statistical system as a finite limit. That occurs when the data presents a downward curving slope, as it does here. 3/

To be concrete, the analysis presented above says: In the 70 years prior to 2021, the worst observed heatwave for the region corresponds to an average of ~35 °C (95 °F). The GEV model estimates the worst possible is ~37 °C (99 °F). But in 2021, we reached 39.5 °C (103 °F). 4/

The GEV model said that 39.5 °C was "impossible", but it happened anyway. Now obviously, if it happened then it was actually possible, so what is it really telling us? 5/

It suggests that the 2021 heatwave may have had a qualitatively different origin or dynamics than all the other Pacific Northwest heatwaves of the last 70 years. 6/

That kind of thing happens sometimes with extremes in physical systems. For example, 70 years of normal rain data may badly fail to predict how much rain is possible during a hurricane, because a hurricane is dynamically different from normal rain-producing processes. 7/

The statistics suggest that the Pacific Northwest heat storm was not merely more extreme than past events, but perhaps also qualitatively different. So, *if* the event was qualitatively different from past events, then we ask in what way? 8/

The first option is that the heat storm was a proverbial hurricane, e.g. a rare dynamical interaction that has always been possible, but so rare that in 70 years of data we never observed a weather pattern that was qualitatively similar. 9/

The second option is that we are seeing unfamiliar dynamics because the climate system has changed at large scales in ways we don't yet fully understand. I consider this the scarier option. 10/

Right now, we don't know the answer. In all likelihood, entire PhDs will be written about the Pacific Northwest heat storm. But nature has thrown us a scary curve ball, and we'll have to wait and see if this was just an exceedingly rare one-off or a sign of more to come. 11/11

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Was the Siberian heatwave last year not similarly beyond prior model estimates?

It covered a larger area, afaik and the deviations from the norm were at least as great.

Should that be seen as supporting evidence for a qualitative shift?

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18 hours ago, etudiant said:

Was the Siberian heatwave last year not similarly beyond prior model estimates?

It covered a larger area, afaik and the deviations from the norm were at least as great.

Should that be seen as supporting evidence for a qualitative shift?

My understanding is that though much longer, the deviations were not as great in terms of standard deviations. Being a continental climate the variability is greater.

but, yes people have been making the argument for a qualitative shift in climate for some time now. The increase in extremes has been slightly larger than one might expect from a simple shift in the means. There’s the whole wavy jet hypothesis which has some empirical and theoretical  evidence.

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Not done with the heat yet, back up to around 38 C in southern BC today. 

We had a nice break for about 2-3 days, and last night's low of 15 C was welcome. Temperatures inside non-a/c buildings have returned to fairly comfortable values but now we have a few more days of this reduced brand of heat. 

By the way I had assumed the Warfield climate station was actually in Warfield, but it appears to be about a mile north in a decommissioned industrial facility formerly associated with the Trail smelter, and located about 0.5 miles west of the highway running north out of Trail, in fairly flat and barren land that is largely exposed rock and dirt. So it's not quite as sheltered as I thought it might be if in the village of Warfield which has a lot of trees around.

Thus I would modify previous comments about adding a degree to get Trail BC equivalent readings, this site is probably as barren and exposed as any part of Trail even if slightly higher above sea level.

I would call them on this site choice except for the fact that much of the urban area of Trail is similarly rocky and barren so perhaps it is a good choice to be representative. Up the hill here there is a lot more shade from trees that survived the smelter years. It did not feel like that shade was doing us a lot of good back in the severe heat wave however.

Another interesting observation -- the Columbia River is running quite high and fast, due to snow melt at high elevations up around the Revelstoke region. It had peaked in late May and early June at fairly moderate levels, as it usually does in these flood-controlled times (Trail used to get some fairly severe flooding in the spring runoff), but now it's at least a foot and probably two feet higher. There is a huge infestation of moths in some parts of the Columbia valley, driving at night exposes you to a mass casualty event that needs extensive car cleaning work the next day. It sounds like driving through a hailstorm. 

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If today and tomorrow average 37 C here, there will be a 30-day interval from June 17 to July 16 with an average high of 37 C. That is about 7 to 8 deg above normal (C deg = 1.8 F deg). Quite the anomaly, I would imagine the previous maximum anomaly in the summer in this region was half of that. Normally the next 30 days are the hottest portion of the summer so if this goes on another 30 days ... well I hope it doesn't, the results will not be good if it stays this hot and dry (in the 30 days the official rainfall is 0.8 mm which is not enough to drown the spiders building webs in the rain gauge. At my location I estimate 3-5 mm fell (it was just one brief interlude about a week ago that has left no trace). 

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16 hours ago, Roger Smith said:

If today and tomorrow average 37 C here, there will be a 30-day interval from June 17 to July 16 with an average high of 37 C. That is about 7 to 8 deg above normal (C deg = 1.8 F deg). Quite the anomaly, I would imagine the previous maximum anomaly in the summer in this region was half of that. Normally the next 30 days are the hottest portion of the summer so if this goes on another 30 days ... well I hope it doesn't, the results will not be good if it stays this hot and dry (in the 30 days the official rainfall is 0.8 mm which is not enough to drown the spiders building webs in the rain gauge. At my location I estimate 3-5 mm fell (it was just one brief interlude about a week ago that has left no trace). 

sounds like you guys are on the way to experiencing what Siberia did last year.

 

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16 hours ago, bluewave said:

No surprise that the Northern Hemisphere mid-latitude land set a new June heat record by a significant margin.

 

 

In layman’s terms, is this saying June was nearly a full degree Fahrenheit warmer than ever recorded, even when averaged over a massive portion of the world?

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I am old enough to remember the 1966 heat wave in the east and this reminds me of that, weeks of mid to high 90s with low humidity levels, a few slightly cooler days in between and no significant rainfall. But in terms of anomaly this is more significant (1966 peaked around 98 to 100 F at various locations), the only thing I can really compare this to would be the 1936 heat wave in some parts of the central U.S., or maybe in terms of anomaly, Dec 2015 in many areas. This is a fairly warm area in an average summer but quite often we don't get this sort of weather until about now, having it from mid-June onward is the really odd part. Late June usually brings one or two cool and wet intervals and July is rarely this dry, August more often has a long dry spell that breaks towards the end of the month.

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On 7/16/2021 at 2:02 PM, Roger Smith said:

I am old enough to remember the 1966 heat wave in the east and this reminds me of that, weeks of mid to high 90s with low humidity levels, a few slightly cooler days in between and no significant rainfall. But in terms of anomaly this is more significant (1966 peaked around 98 to 100 F at various locations), the only thing I can really compare this to would be the 1936 heat wave in some parts of the central U.S., or maybe in terms of anomaly, Dec 2015 in many areas. This is a fairly warm area in an average summer but quite often we don't get this sort of weather until about now, having it from mid-June onward is the really odd part. Late June usually brings one or two cool and wet intervals and July is rarely this dry, August more often has a long dry spell that breaks towards the end of the month.

I only wish we had 1966 type heat back east, all this humidity sucks, and I'm constantly having to spray to get rid of all the insects trying to get inside.  Seems like hot dry weather has much less insects trying to come inside.

 

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  • 2 weeks later...
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4 hours ago, donsutherland1 said:

Select high temperatures for August 11, 2021:

Dallesport, WA: 110° (old record: 109°, 1981)
Eugene, OR: 102°
Medford, OR: 104°
Pendleton, OR: 101°
Portland: 102° (tied record set in 1977)
Richland, WA: 107° (tied record set in 1958)
Salem, OR: 103°
Seattle: 91°

 

Peak heat on Friday Don?  When was the last time both NYC and Seattle hit 95 or higher on the same day?

 

 

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7 hours ago, donsutherland1 said:

It has happened just twice:

July 23, 1991: NYC 99; SEA 99

August 4, 1993: NYC 96; SEA 95

wow those were two of the all time hot summers at NYC, both had 39 90+ days!

 

that day in 1991 was one degree off at both for being the first ever same day triple digit temps at both locations!

 

 

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773 
SXUS76 KSEW 130134
RERSEW

RECORD EVENT REPORT
NATIONAL WEATHER SERVICE SEATTLE
634 PM PDT THU AUG 12 2021

...ALL TIME HIGH TEMPERATURE SET TODAY AT BELLINGHAM WA...

...MULTIPLE DAILY RECORD HIGH TEMPERATURES SET TODAY ACROSS WESTERN 
WASHINGTON...

BELLINGHAM WA RECORDED A TEMPERATURE OF 100 DEGREES TODAY, REACHING 
THIS MARK FOR THE FIRST TIME ON RECORD. THE PREVIOUS RECORD MAXIMUM 
TEMPERATURE WAS 99 DEGREES SET EARLIER THIS YEAR ON JUNE 28. RECORDS 
DATE BACK TO 1949.

THIS IS, OF COURSE, ALSO THE RECORD WARMEST TEMPERATURE RECORDED AT 
BELLINGHAM IN THE MONTH OF AUGUST. THE PREVIOUS MARK WAS 94 DEGREES, 
SET ON BOTH AUGUST 8 1978 AND AUGUST 9 1960.

IN ADDITION TO BELLINGHAM, SEVERAL OTHER LOCATIONS SET OR TIED 
RECORD MAXIMUM TEMPERATURES FOR THE DATE, AUGUST 12.

LOCATION     HIGH TEMPERATURE     PREVIOUS RECORD / DATE 
---------------------------------------------------------
BELLINGHAM     100                  85  / 1956    
OLYMPIA        96 (T)               96  / 1977  
NWS SEATTLE    93 (T)               93  / 1977
HOQUIAM        88                   84  / 1977 


$$

CULLEN
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Select high temperatures for August 13, 2021:

Bellingham, WA: 100° (old record: 85°, 1956 and 1977) ***New All-Time Record***
Boise: 100°
Dallesport, WA: 108° (old record: 107°, 1977)
Eugene, OR: 104° (old record: 102°, 1977)
Medford, OR: 103°
Olympia: 96° (tied record set in 1977)
Pendleton, OR: 102°
Portland: 103° ***Record-tying 5th 100° day this year***
Salem, OR: 103°
Seattle: 95°

Portland's minimum temperature of 70° set a new August record for highest minimum temperature.

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On 8/12/2021 at 9:07 PM, donsutherland1 said:

On June 28, 2021, the temperature at Bellingham, WA reached 99°, which broke the all-time record of 96° that had been set on July 29, 2009. Today, the temperature rose to 100° at Bellingham, which eclipsed the all-time record set during the historic June heat wave.

Wow Bellingham was hotter than Seattle?
 

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On 8/13/2021 at 10:57 AM, donsutherland1 said:


Select high temperatures for August 13, 2021:

Bellingham, WA: 100° (old record: 85°, 1956 and 1977) ***New All-Time Record***
Boise: 100°
Dallesport, WA: 108° (old record: 107°, 1977)
Eugene, OR: 104° (old record: 102°, 1977)
Medford, OR: 103°
Olympia: 96° (tied record set in 1977)
Pendleton, OR: 102°
Portland: 103° ***Record-tying 5th 100° day this year***
Salem, OR: 103°
Seattle: 95°

Portland's minimum temperature of 70° set a new August record for highest minimum temperature.

Well Seattle reached 95 but NYC did not.

 

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