donsutherland1

The 6/28/2021 12z sounding (500 mb heights):

Yesterday’s 104-degree reading in Seattle was more than 3.6 sigma above the mean June-August high temperature (1991-2020 base). It would be the equivalent of 108 degrees in Central Park or 109 degrees in Chicago.

8 am PDT: Seattle: 90

The evolution of the synoptic features. It looks destined to slowly move east-northeastward through Canada while moderating over time.

Portland could have its 3rd consecutive all-time record.

British Columbia Records courtesy of Environment Canada: Weather summary for British Columbia issued by Environment Canada at 12:05 a.m. PDT Monday 28 June 2021. Discussion. The following area sets the Canadian maximum temperature record on Sunday June 27, 2021: Lytton Area (Lytton RCS) New Canadian record of 46.6 Old record of 45.0 set in July 5, 1937 in Yellow Grass and Midale, SK. The following areas set a daily maximum temperature record on June 27, 2021: Abbotsford Area (Abbotsford A) New record of 41.5 Old record of 32.3 set in 2015 Records in this area have been kept since 1944 Agassiz Area (Agassiz RCS) New record of 40.4 Old record of 33.7 set in 2015 Records in this area have been kept since 1889 Bella Bella Area (Bella Bella) New record of 34.2 Old record of 24.3 set in 1995 Records in this area have been kept since 1977 Bella Coola Area (Bella Coola Airport) New record of 36.0 Old record of 35.0 set in 1895 Records in this area have been kept since 1895 Blue River Area (Blue River CS) New record of 37.3 Old record of 34.7 set in 2015 Records in this area have been kept since 1946 Burns Lake Area (Burns Lake Decker Lake) New record of 38.1 Old record of 29.5 set in 1992 Records in this area have been kept since 1949 Cache Creek Area (Ashcroft) New record of 45.0 Old record of 40.1 set in 2015 Records in this area have been kept since 1944 Clearwater Area (Clearwater Auto) New record of 42.3 Old record of 36.9 set in 2015 Records in this area have been kept since 1913 Clinton Area (Clinton RCS) New record of 39.0 Old record of 32.2 set in 2015 Records in this area have been kept since 1974 Comox Area (Comox A) New record of 38.0 Old record of 31.1 set in 2015 Records in this area have been kept since 1914 Courtenay Area (Comox A) New record of 38.0 Old record of 31.1 set in 2015 Records in this area have been kept since 1914 Creston Area (Creston Campbell Scientific) New record of 39.0 Old record of 37.9 set in 2015 Records in this area have been kept since 1912 Dawson Creek Area (Dawson Creek A) New record of 36.1 Old record of 28.2 set in 2000 Records in this area have been kept since 1926 Dease Lake Area (Dease Lake (AUT)) New record of 32.0 Old record of 27.6 set in 1982 Records in this area have been kept since 1944 Esquimalt Area (Victoria Gonzales CS) New record of 38.3 Old record of 27.8 set in 1951 Records in this area have been kept since 1874 Fort Nelson Area (Fort Nelson) New record of 35.8 Old record of 30.4 set in 2004 Records in this area have been kept since 1937 Fort St. John Area (Fort St. John A) New record of 35.1 Old record of 30.0 set in 1928 Records in this area have been kept since 1910 Gibsons Area (Sechelt Aut) New record of 39.6 Old record of 30.6 set in 2015 Records in this area have been kept since 1949 Golden Area (Golden Airport) New record of 36.7 Old record of 35.0 set in 1925 Records in this area have been kept since 1902 Gonzales Point Area (Victoria Gonzales CS) New record of 38.3 Old record of 27.8 set in 1951 Records in this area have been kept since 1874 Hope Area (Hope Airport) New record of 39.9 Old record of 33.4 set in 2015 Records in this area have been kept since 1936 Kamloops Area (Kamloops A) New record of 44.0 Old record of 38.2 set in 2015 Records in this area have been kept since 1890 Kelowna Area (Kelowna UBCO) New record of 41.5 Old record of 38.1 set in 2015 Records in this area have been kept since 1899 Lillooet Area (Lillooet) New record of 44.8 Old record of 39.8 set in 2015 Records in this area have been kept since 1917 Lytton Area (Lytton RCS) New record of 46.6 Old record of 40.2 set in 2015 Records in this area have been kept since 1921 Mackenzie Area (Mackenzie Airport Auto) New record of 37.3 Old record of 28.4 set in 2015 Records in this area have been kept since 1971 Malahat Area (Malahat) New record of 38.2 Old record of 32.6 set in 2015 Records in this area have been kept since 1986 Merritt Area (Merritt) New record of 42.2 Old record of 38.0 set in 2015 Records in this area have been kept since 1918 Nakusp Area (Nakusp CS) New record of 36.1 Old record of 35.3 set in 2015 Records in this area have been kept since 1966 Osoyoos Area (Osoyoos CS) New record of 42.0 Old record of 40.9 set in 2015 Records in this area have been kept since 1954 Pemberton Area (Pemberton Airport CS) New record of 40.9 Old record of 38.0 set in 2015 Records in this area have been kept since 1908 Penticton Area (Penticton A) New record of 40.5 Old record of 37.8 set in 1925 Records in this area have been kept since 1907 Pitt Meadows Area (Pitt Meadows CS) New record of 40.0 Old record of 33.9 set in 2015 Records in this area have been kept since 1874 Port Alberni Area (Port Alberni (AUT)) New record of 41.3 Old record of 37.0 set in 2015 Records in this area have been kept since 1900 Port Hardy Area (Port Hardy A) New record of 30.2 Old record of 21.3 set in 1995 Records in this area have been kept since 1944 Powell River Area (Powell River) New record of 36.6 Old record of 30.0 set in 2015 Records in this area have been kept since 1924 Prince George Area (Prince George Airport Auto) New record of 36.4 Old record of 29.4 set in 1928 Records in this area have been kept since 1912 Prince Rupert Area (Prince Rupert) New record of 30.0 Old record of 20.4 set in 2013 Records in this area have been kept since 1908 Princeton Area (Princeton CS) New record of 41.4 Old record of 38.5 set in 2015 Records in this area have been kept since 1893 Puntzi Mountain Area (Puntzi Mountain (AUT)) New record of 38.1 Old record of 31.7 set in 2015 Records in this area have been kept since 1959 Quesnel Area (Quesnel Airport Auto) New record of 39.9 Old record of 36.7 set in 1925 Records in this area have been kept since 1893 Sandspit Area (Sandspit Airport Auto) New record of 23.8 Old record of 20.6 set in 2016 Records in this area have been kept since 1945 Sechelt Area (Sechelt Aut) New record of 39.6 Old record of 30.6 set in 2015 Records in this area have been kept since 1956 Smithers Area (Smithers Airport Auto) New record of 37.1 Old record of 29.9 set in 1992 Records in this area have been kept since 1938 Squamish Area (Squamish Airport) New record of 41.2 Old record of 32.3 set in 2015 Records in this area have been kept since 1960 Summerland Area (Summerland CS) New record of 38.8 Old record of 36.5 set in 2015 Records in this area have been kept since 1907 Tatlayoko Lake Area (Tatlayoko Lake RCS) New record of 37.1 Old record of 31.3 set in 2015 Records in this area have been kept since 1930 Terrace Area (Terrace A) New record of 35.6 Old record of 30.1 set in 2016 Records in this area have been kept since 1912 Trail Area (Warfield RCS) New record of 42.3 Old record of 40.6 set in 2015 Records in this area have been kept since 1928 Vancouver Area (Vancouver Intl A) New record of 31.1 Old record of 27.2 set in 1935 Records in this area have been kept since 1896 Vernon Area (Vernon Auto) New record of 41.5 Old record of 37.3 set in 2015 Records in this area have been kept since 1900 Victoria Area (Victoria Intl A) New record of 37.7 Old record of 29.5 set in 1995 Records in this area have been kept since 1914 Victoria Harbour Area (Victoria Gonzales CS) New record of 38.3 Old record of 27.8 set in 1951 Records in this area have been kept since 1874 Victoria (Hartland) Area (Victoria Gonzales CS) New record of 38.3 Old record of 27.8 set in 1951 Records in this area have been kept since 1874 Victoria (University of) Area (Victoria Gonzales CS) New record of 38.3 Old record of 27.8 set in 1951 Records in this area have been kept since 1874 Whistler Area (Whistler - Nesters) New record of 40.2 Old record of 34.8 set in 2015 Records in this area have been kept since 1950 White Rock Area (White Rock Campbell Scientific) New record of 36.9 Old record of 29.2 set in 1995 Records in this area have been kept since 1929 Williams Lake Area (Williams Lake A) New record of 37.2 Old record of 30.3 set in 2015 Records in this area have been kept since 1960 Yoho (National Park) Area (Yoho Park) New record of 33.3 Old record of 31.1 set in 1925 Records in this area have been kept since 1923 Note: the temperature records reported here have been derived from a selection of historical stations in each 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

Morning thoughts... It will be variably cloudy and hot. There could be a widely scattered afternoon shower or thundershower. Temperatures will likely reach the lower and perhaps middle 90s in most places today. Likely high temperatures around the region include: New York City (Central Park): 91° Newark: 98° Philadelphia: 93° Normals: New York City: 30-Year: 83.2°; 15-Year: 83.3° Newark: 30-Year: 85.5°; 15-Year: 85.8° Philadelphia: 30-Year: 86.6°; 15-Year: 87.0° Much above normal temperatures will likely persist through mid-week. Yesterday, Portland (112°) and Seattle (104°) established new all-time high temperature records. Lytton, BC set a national Canadian high temperature record of 116°. Today, Seattle and Portland will likely further increase their all-time high temperature records that they set yesterday. Lytton could challenge its record, as well. Daily Records for June 26: Portland: 100°, 2008 (Forecast: 108° to 120°) Seattle: 91°, 2008 (Forecast: 103° to 115°) *-Forecast range is 1 sigma below and above the forecast mean. The huge model spread suggests a 43% implied probability that Seattle will reach 110° and that Portland will reach 115°.

Seattle finished with an all-time high of 104 today.

Lytton, BC. Data as per Environment Canada: 46.6C/116F. https://twitter.com/ECCCWeatherBC/status/1409306438074310661?s=20

A very warm and humid air mass remains in place over the Middle Atlantic and southern New England areas. Under partly sunny skies, temperatures will likely reach the lower 90s in many parts of the region. A shower or thundershower is possible. The warmth will continue through at least mid-week. Meanwhile, out West an unprecedented heat event shattered numerous all-time high temperature records. Preliminary high temperatures included: Eugene, OR: 111° (old record: 98°, 2015) ***New All-Time Record*** Fort Nelson, BC: 96° (old record: 87°, 2015) ***New June Record*** Kamloops, BC: 110° (old record: 99°, 2006) ***New All-Time Record*** Lillooet, BC: 113° (old record: 104°, 2015) ***New All-Time Record*** Lytton, BC: 116° (old record: 96°, 2000) ***New All-Time Record; New National Record for Canada*** Medford, OR: 113° (old record: 104°, 2015) ***New June Record*** Portland: 112° (old record: 98°, 2000) ***New All-Time Record*** Seattle: 104° (old record: 92°, 2015) ***New All-Time Record*** Spokane: 102° (tied record set in 2015) The Dalles, OR: 115° (old record: 105°, 2006) ***New June Record; Tied All-Time Record*** Vancouver: 87° (old record: 79°, 1937) Victoria: 99° (old record: 85°, 1995) ***New All-Time Record*** Yakima, WA: 108° (tied record set in 2015) ***Tied June Record*** Additional all-time high temperature records will likely be surpassed tomorrow. After tomorrow, 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 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 28: 100°, 2008 June 29: 97°, 1951 June record: 112° All-time record: 112° Seattle: June 28: 91°, 1995 and 2008 June 29: 93°, 1987 June record: 103° All-time record: 103° Spokane: 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 95% 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 -5.62 today. The preliminary Arctic Oscillation (AO) figure was +0.456 today. On June 25 the MJO was in Phase 1 at an amplitude of 1.357 (RMM). The June 24-adjusted amplitude was 1.305 (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 74.1° (2.1° above normal).

The hourly data and hot spots data are inconsistent today. We’ll know a little later what the final high temperature was.

Earlier, Environment Canada posted that Lytton, BC had reached: 46.1C/115F, on its website. However, the 3 pm PDT temperature now shows 44.1C, so the earlier number is in question.

It sure looks like it.

No. There’s no indication that this air mass will ever impact this region.

At 2 pm, PDT, Portland had a temperature of 109°. That destroys the daily record of 98°, set in 2000. It also surpasses the all-time record high of 108° that was set just yesterday. The difference over yesterday at this time has increased to 13°.

This morning, Portland recorded a low temperature of 73°. That broke the existing daily record high minimum temperature of 71°, which was set in 2015. It was also Portland's record-tying second consecutive 70° minimum temperature. That record was set during July 16-17, 1941 and tied on July 27-28, 1998 and July 28-29, 2009. This is the only occurrence of such a streak in June.

115. I ran the numbers.

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.