donsutherland1

AGW and the severe multi-year drought can't fully be disentangled. While internal variability leads to drought conditions, AGW increases the probability of such outcomes through shifting precipitation patterns and greater drying of soil from higher temperatures. How much is climate change contributing? Detailed multi-model analysis, which is utilized during attribution studies, would provide a good answer. But a rough approximation is possible from the following approach: (Probability of an event under the current climate - Probability of an event under the baseline climate) / Probability of an event under the current climate This formula provides a good approximation, because climate science has concluded with very high confidence that most of the recent warming has resulted from growing anthropogenic greenhouse gas forcing (actually > 100%, because a small decline in solar irradiance has made a negative contribution). I ran some numbers for Seattle. For the baseline, I used the June-August 1951-80 period (the GISS baseline, as the Seattle-Tacoma record only goes back to 1945). For the current climate, I used the 1991-20 base period. Probabilities: 100-degree day: 1951-80: 0.035%; 1991-20: 0.078% Actual: 1951-80: 0%; 1991-20: 0.07% Then using the probabilities, I got: (.0078 - .0035)/0.0078 = approximately 55%. Climate change made such events 55% more likely For 105-degree days, the climate change contribution would be 61% The actual probabilities could be somewhat higher, as climate change has made the kind of resonance events involved in this epic heat event more likely. @bluewaveposted a good paper on this topic earlier in the thread.

Pendleton, OR reached 119 in 1898.

Not necessarily. The ridge will be drifting north and east, so its influence over Portland will be a little less impactful. Statistically, Seattle’s 102 high yesterday would be the equivalent of a 107 high in Central Park.

This morning, Seattle had a low temperature of 73°. That shattered the old record of 63° from 2015. It also set a new all-time record high minimum temperature. The previous record was 71°, which was set on July 29, 2009.

Yes, it’s possible. This is an unprecedented heat event.

Morning thoughts... It will be variably cloudy and very warm. There could be an afternoon shower or thundershower. Temperatures will likely reach the upper 80s and lower 90s in most places today. Likely high temperatures around the region include: New York City (Central Park): 88° Newark: 93° Philadelphia: 91° Normals: New York City: 30-Year: 82.9°; 15-Year: 83.0° Newark: 30-Year: 85.3°; 15-Year: 85.5° Philadelphia: 30-Year: 86.4°; 15-Year: 86.7° Tomorrow will be even warmer. Yesterday, Lytton, BC set an all-time record high temperature of 111°, which also set a new record for Canada’s highest-ever June temperature. Today, Seattle and Portland will likely set new all-time high temperature records. Daily Records for June 26: Portland: 98°, 2000 (Forecast: 108° to 120°) Seattle: 92°, 2015 (Forecast: 99° to 109°) *-Forecast range is 1 sigma below and above the forecast mean.

Yes.

Final figure from Lytton was 43.8C. That set a new Canadian national high temperature record for June.

I suspect that there will be such a study as the event is virtually unprecedented and it has affected millions of people.

Lytton, BC: 43.8C/111F

And it reached 108 at 6 pm PDT to set a new record.

A very warm and humid air mass now covers the Middle Atlantic and southern New England areas. Under partly sunny skies, temperatures could approach or reach 90° in parts of the region tomorrow. A shower or thundershower is possible. The warmth will continue through at least mid-week next week. Meanwhile, out West a historic, if not unprecedented heat event, is now underway. The ongoing epic heatwave in the Pacific Northwest fried numerous June monthly records. Preliminary high temperatures included: Eugene, OR: 103° (old record: 99°, 2015) ***New June Record*** Kamloops, BC: 103° (old record: 101°, 2006) ***New June Record*** Lillooet, BC: 109° (old record: 98°, 2002) ***New All-Time Record*** Lytton, BC: 111° (old record: 104°, 2006) ***New All-Time Record*** Portland: 108° (old record: 102°, 2006) ***New All-Time Record*** Seattle: 102° (old record: 90°, 2006) ***New June Record*** The Dalles, OR: 110° (old record: 103°, 2017) ***Tied June Record*** Vancouver: 87° (old record: 86°, 2002) ***New June Record*** Victoria, BC: 95° (old record: 85°, 2002) ***New June Record for the 2nd Consecutive Day*** Yakima, WA: 104° (tied record set in 2015) This heatwave will further intensify tomorrow. Numerous all-time high temperature records will likely be smashed, some by large margins. After Monday, the core of the heat will shift somewhat to the north and east. Readings will remain much above normal in parts of eastern Washington State, Oregon, Idaho, and eastern British Columbia. Records for select cities: Kamloops, BC: June 27: 99° (37.1°C), 2006 June 28: 100° (37.7°C), 2008 June 29: 102° (39.1°C), 2008 June record: 103° (39.5°C) All-time record: 105° (40.8°C) Portland: June 27: 98°, 2000 June 28: 100°, 2008 June 29: 97°, 1951 June record: 108° All-time record: 108° Seattle: June 27: 92°, 2015 June 28: 91°, 1995 and 2008 June 29: 93°, 1987 June record: 101° All-time record: 103° Spokane: June 27: 102°, 2015 June 28: 105°, 2015 June 29: 98°, 1939 June record: 105° All-time record: 108° Climate change has increased the frequency, magnitude, and duration of extreme heat events in the United States and worldwide. Further increases are likely in coming decades as the world's climate continues to warm. During the 1971-00 period, there was a statistical 0.9% probability that the temperature would reach or exceed 90° during June 26-28. For the 1991-20 period, that figure had increased to 2.0%. That's an implied 55% increase tied to climate change. Actual outcomes saw Seattle record 90° temperatures on 1.1% of days within that period during 1971-00 and 4.4% during the 1991-20 timeframe. For Portland, the statistical probability of a 90° day during the June 26-28 period was 6.2% during the 1971-00 period and 10.4% during the 1991-20 period. That's an implied 40% increase tied to climate change. The actual outcomes were 6.6% during the 1971-00 period and 12.2% during the 1991-20 period. That actual outcomes exceeded statistical outcomes is consistent with ongoing warming. In large part on account of Phoenix's recent extreme heat event, there is an implied 89% probability that June 2021 will become Phoenix's warmest June on record with a mean temperature near 95.0°. The existing record of 94.8° was set in 2013 and tied in 2016. The ENSO Region 1+2 anomaly was +0.4°C and the Region 3.4 anomaly was -0.5°C for the week centered around June 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.30°C and the ENSO Region 3.4 anomaly has averaged -0.25°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +5.83 today. The preliminary Arctic Oscillation (AO) figure was +0.456 today. On June 24 the MJO was in Phase 1 at an amplitude of 1.308 (RMM). The June 23-adjusted amplitude was 1.532 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Since 1896, 76% of years that saw Phoenix reach 115° or above in June, as occurred this year, had a warmer than July-August in the Middle Atlantic region. The ratio of top 30 July-August temperatures relative to bottom 30 temperatures was 6:1 in favor of the warmth. Overall, the ingredients continue to fall into place for a warmer than normal to potentially hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a warmer than normal June (1991-2020 normal). June will likely finish with a mean temperature near 74.0° (2.0° above normal).

No. That’s a new June record. The all-time high is 103. It might be matched today and should be broken tomorrow.

This is a really high impact heat event. I saw that YVR surpassed its monthly record a short time ago. Victoria has set new monthly records for 2 consecutive days. Lillooet was at 42.2C. It will be interesting to see the final numbers when Environment Canada posts them tomorrow. Moreover, the worst is yet to come in much of BC, WA, and OR.

Lillooet was up to 41.6C at 3 pm PDT. That’s the first 40C temperature on record there in June.

At 3 pm PDT, Seattle had a temperature of 98° . That sets a new June monthly record high temperature.

Historic sounding: https://twitter.com/ensembleator/status/1408795609516052485?s=20 Sounding from the above tweet:

At 2 pm PDT, Seattle had a temperature of 96° today. That broke the daily and monthly record high figure of 90°, which was set on June 26, 2006. It also tied the monthly record that was first set on June 9, 1955 and tied on June 30, 1995 and June 25, 2017.

Seattle had a low temperature of 69° today. That broke the daily and monthly record high figure of 67°, which was set on June 26, 2006.

Continuing the discussion of the point made about changes in minimum temperatures, there is also a climate change component involved with the UHI Effect Here’s one paper on that topic that explains what is happening: https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.4688 In sum, the combination of climate change and the UHI Effect have led to more rapid warming at night.

Fresh off yesterday's June-record 93° temperature, Victoria, BC has set a new daily record high for June 26. At 10 am PDT, the temperature was 86°. That broke the previous daily record of 85°, which was set in 2017. Elsewhere in the Pacific Northwest, 10 am temperatures included: Eugene, OR: 92° Lytton, BC: 92° Portland: 82° Seattle: 85°

In a few decades with a general business-as-usual energy policy, the right synoptic set up might produce such extremes. But it would still be a very rare event.

There are some differences between then and now. We’ve already seen more heat dome ridges pop up particularly over drought-stricken areas. The climate is also warmer than it was then. While the kind of extreme heat we’ve seen out West is probably not very likely, but cannot be ruled out, a sustained above-to-much above normal temperature regime remains likely.

Morning thoughts... It will be variably cloudy and warmer. Some drizzle or light rain is possible in places this morning. There could be an afternoon shower or thundershower. Temperatures will likely reach the lower and middle 80s in most places today. Likely high temperatures around the region include: New York City (Central Park): 83° Newark: 87° Philadelphia: 85° Normals: New York City: 30-Year: 82.7°; 15-Year: 82.7° Newark: 30-Year: 85.0°; 15-Year: 85.2° Philadelphia: 30-Year: 86.2°; 15-Year: 86.5° Tomorrow will be even warmer. Yesterday, Victoria, BC set a June record high temperature of 93° and Lytton, BC set a daily record high temperature of 103°. This marked the beginning of a monster heatwave that will engulf the Pacific Northwest over the next few days. At its height numerous June and perhaps all-time high temperature records will tumble, including at Portland and Seattle. Today, Seattle will very likely set a new daily record high temperature. Portland will likely break its monthly record high temperature (102°) and could challenge its all-time record high temperature (107°). There is an implied 40% probability that Portland will reach or exceed its all-time high today. Tomorrow will be even hotter. Daily Records for June 26: Portland: 102°, 2006 (Forecast: 102° to 110°) Seattle: 90°, 2006 (Forecast: 95° to 101°) *-Forecast range is 1 sigma below and above the forecast mean.

A very warm weekend lies ahead. Temperatures could approach or reach 90° in parts of the region on Sunday. The warmth will continue through at least mid-week next week. In the Pacific Northwest, a historic and potentially unprecedented heatwave began to descend on the region. In response, parts of Oregon, Washington, and British Columbia saw temperatures soar into the 90s today. A few locations even exceeded 100° including the following sites: The Dalles, OR: 102° Ephrata, WA: 100° Lytton, BC: 102°/38.7°C (old record: 101°/38.2°C) Omak, WA: 100° This weekend into early next week could see the most extreme heat parts of that region have ever experienced. Monthly and possibly all-time record high temperatures could be challenged or broken. That includes the Portland and Seattle areas. After Monday, the core of the heat will shift somewhat to the north and east. Readings will remain much above normal in parts of eastern Washington State, Idaho, and eastern British Columbia. Records for select cities: Kamloops, BC: June 26: 102° (38.4°C), 2006 June 27: 99° (37.1°C), 2006 June 28: 100° (37.7°C), 2008 June 29: 102° (39.1°C), 2008 June record: 102° (39.1°C) All-time record: 105° (40.8°C) Portland: June 26: 102°, 2006 June 27: 98°, 2000 June 28: 100°, 2008 June 29: 97°, 1951 June record: 102° All-time record: 107° Seattle: June 26: 90°, 2006 June 27: 92°, 2015 June 28: 91°, 1995 and 2008 June 29: 93°, 1987 June record: 96° All-time record: 103° Spokane: June 26: 100°, 1925 June 27: 102°, 2015 June 28: 105°, 2015 June 29: 98°, 1939 June record: 105° All-time record: 108° Climate change has increased the frequency, magnitude, and duration of extreme heat events in the United States and worldwide. Further increases are likely in coming decades as the world's climate continues to warm. During the 1971-00 period, there was a statistical 0.9% probability that the temperature would reach or exceed 90° during June 26-28. For the 1991-20 period, that figure had increased to 2.0%. That's an implied 55% increase tied to climate change. Actual outcomes saw Seattle record 90° temperatures on 1.1% of days within that period during 1971-00 and 4.4% during the 1991-20 timeframe. For Portland, the statistical probability of a 90° day during the June 26-28 period was 6.2% during the 1971-00 period and 10.4% during the 1991-20 period. That's an implied 40% increase tied to climate change. The actual outcomes were 6.6% during the 1971-00 period and 12.2% during the 1991-20 period. That actual outcomes exceeded statistical outcomes is consistent with ongoing warming. In large part on account of Phoenix's recent extreme heat event, there is an implied 83% probability that June 2021 will become Phoenix's warmest June on record with a mean temperature near 95.1°. The existing record of 94.8° was set in 2013 and tied in 2016. The ENSO Region 1+2 anomaly was +0.4°C and the Region 3.4 anomaly was -0.5°C for the week centered around June 16. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.30°C and the ENSO Region 3.4 anomaly has averaged -0.25°C. Neutral ENSO conditions will likely prevail into at least mid-summer. The SOI was +10.54 today. The preliminary Arctic Oscillation (AO) figure was +0.210 today. On June 23 the MJO was in Phase 1 at an amplitude of 1.532 (RMM). The June 22-adjusted amplitude was 1.207 (RMM). In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer. Since 1896, 76% of years that saw Phoenix reach 115° or above in June, as occurred this year, had a warmer than July-August in the Middle Atlantic region. The ratio of top 30 July-August temperatures relative to bottom 30 temperatures was 6:1 in favor of the warmth. Overall, the ingredients continue to fall into place for a warmer than normal to potentially hot summer. Based on sensitivity analysis applied to the latest guidance, there is an implied 98% probability that New York City will have a warmer than normal June (1991-2020 normal). June will likely finish with a mean temperature near 73.9° (1.9° above normal).