donsutherland1 Posted September 1 Share Posted September 1 In what has become a seemingly regular occurrence beginning in 2020, Phoenix has experienced its hottest summer on record. Since 2020, Phoenix has eclipsed the summer mark in 2020, 2023, and again this year. A major theme, as was the case in 2020 and 2023 when the heat set in, was its persistence. Summer 2024 got off to a blazing start with its hottest June, by far, on record. The sizzling June was followed by Phoenix’s second hottest July and second hottest month on record. July featured an 11-day extreme heat event (Clarke et al., 2014 methodology) during which the temperature reached or exceed 115° on six days. That was the second longest such event on record. Summer concluded with the third hottest August on record. On account of the historic heat, Phoenix saw its longest stretches of 80° or above lows, 100° or above highs, and 105° or above highs: 80° or above lows: 74 days, June 5-August 17; old record: 51 days, July 1-August 20, 2023 100° or above highs: 97 days (as of August 31 and ongoing); old record: 76 days, June 10-August 24, 1993 105° or above highs: 63 days, June 5-August 6; old record: 56 days, June 24-August 18, 2023 Anthropogenic climate change amplified by the urban heat island effect is driving a warming of Arizona’s and Phoenix's summers. Data from a joint May 2024 report published by Climate Central, Red Cross Red Crescent Climate Centre and World Weather Attribution revealed that the influence of climate change has resulted in a 231.1% increase in Arizona’s days with temperatures above the 90th percentile (1991-2020 baseline) over the figure expected without the influence of climate change. The warming has accelerated in recent decades. Between 1950 and 2023, summers have warmed by 0.6° per decade in Phoenix. Since 1980, summers have warmed by 0.9° per decade. As a result, Phoenix has set summer records in 2020, 2023, and now 2024. As a result, the annual number of days on which the high temperature has exceeded the 90th percentile for summer maximum readings (1991-2020 baseline) has increased from 6.5 days during 1961-1990 to 9.99 days during 1991-2020. The most recent 30-year moving average (1995-2024) is 12.7 such days per year (through August 31, 2024). Select highlights: Updates: Phoenix records 100th 80° low temperature of the year Progression of Phoenix's Record Streak of 100° Highs Phoenix and Surrounding Area 100° Highs and 80° Lows U.S. Sites with 110 or More Consecutive 100° Highs and Population Hottest Last 7 Days of September Phoenix Experiences its Hottest September on Record Phoenix's Extreme September 28th and October 1st High Temperatures Phoenix Experiences its Hottest First Week of October on Record Phoenix Sets or Ties Daily High Temperature Records on an Unprecedented 21 Consecutive Days Climate Change not the Urban Heat Island Effect drove Phoenix's Record Autumn Heatwave Southwest Region Summer Trends Phoenix Follows its Hottest Summer with its Warmest Fall on Record 2 2 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 3 Author Share Posted September 3 Phoenix has now reached a record 100 consecutive 100-degree days. 3 2 Link to comment Share on other sites More sharing options...
Typhoon Tip Posted September 5 Share Posted September 5 put a phys.org link over in Global Average Temperature 2024 add s. korea to the list 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 7 Author Share Posted September 7 On September 5, Phoenix recorded a September record-tying 116° high temperature. A day later, Phoenix followed up with a new September monthly record high minimum temperature of 93°, which broke the old record by 2°. In California, Palm Springs recorded a low temperature of 95°, beating the September monthly mark by 3°. That was also tied for the second highest low temperature on record. According to Climate Central's Climate Shift Index, this warmth was made at least 5 times more likely due to climate change. 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 15 Author Share Posted September 15 Yesterday, Phoenix recorded its 100th 80° low of the year, further extending its record. The combination of Urban Heat Island (UHI) Effect and ongoing anthropogenic warming has led to a dramatic explosion of the frequency of such hot nights. 1 1 Link to comment Share on other sites More sharing options...
Typhoon Tip Posted September 15 Share Posted September 15 7 hours ago, donsutherland1 said: Yesterday, Phoenix recorded its 100th 80° low of the year, further extending its record. The combination of Urban Heat Island (UHI) Effect and ongoing anthropogenic warming has led to a dramatic explosion of the frequency of such hot nights. It’s mostly climate change… I’ve never bought it that the urban he Island is a big enough factor in this thing because frankly, the urban heat is has been there since the middle of last century. So it’s on both sides of the trendline, and therefore should be equitable and eliminated as a common factor 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 16 Author Share Posted September 16 Phoenix reached 100° for the 113th consecutive day and 120th day overall this year. Six of the nine years with 120 such days have occurred since 2000 and all have occurred since 1988. Link to comment Share on other sites More sharing options...
GaWx Posted September 16 Share Posted September 16 23 hours ago, Typhoon Tip said: It’s mostly climate change… I’ve never bought it that the urban he Island is a big enough factor in this thing because frankly, the urban heat is has been there since the middle of last century. So it’s on both sides of the trendline, and therefore should be equitable and eliminated as a common factor The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%: https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population 1 Link to comment Share on other sites More sharing options...
bluewave Posted September 17 Share Posted September 17 16 hours ago, GaWx said: The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%: https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population While UHI is the reason for the urban areas like Phoenix running warmer than the rural locations especially at night, climate change is responsible for the whole region having their warmest summer on record including the low population Death Valley area. Link to comment Share on other sites More sharing options...
GaWx Posted September 17 Share Posted September 17 2 hours ago, bluewave said: While UHI is the reason for the urban areas like Phoenix running warmer than the rural locations especially at night, climate change is responsible for the whole region having their warmest summer on record including the low population Death Valley area. Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV. Link to comment Share on other sites More sharing options...
Bhs1975 Posted September 17 Share Posted September 17 Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV.Deserts soak up a lot of heat as it is so I'm not sure there would be much difference compared to the developed areas that has some grass and trees.. 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 17 Author Share Posted September 17 Phoenix saw its record 113-day streak of 100° temperatures end today. Prior to this year, Phoenix has never had a stretch more than 76 days. 3 Link to comment Share on other sites More sharing options...
bluewave Posted September 18 Share Posted September 18 17 hours ago, GaWx said: Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV. Yeah, that’s what I meant by UHI is mostly evident at night. Notice how Phoenix didn’t really stand out with over 100 days this year as there were other Arizona stations with a similar number. But it was the leader in 80° minimums as the urban areas hold onto the heat that builds up during the day. So while climate change lead to urban and rural stations both having their top ranking for warmest summer, Phoenix had many more 80° minimums due to UHI. Phoenix had their warmest minimum average temperature of 87.5°. Casa Grande to the south with a population of only 56K had their warmest average minimum for the summer but it was cooler at 78.6. Care free also had their warmest average minimum temperature at 77.7 but with a population closer to onky 4K. So the differential is the UHI effect. The number 1 ranking is due to climate change. Climate perspectives site for comparison between rural, suburban, and urban sites with rankings, departures, and actual temperatures. https://sercc.com/climate-perspectives/ Data below from XMACIS Phoenix similar number of 100° days at 120. Data for January 1, 2024 through September 18, 2024Click column heading to sort ascending, click again to sort descending. HAVASU ARIZONA RAWS 125 TACNA 3 NE COOP 124 ROBSON RANCH COOP 121 PHOENIX AIRPORT WBAN 120 Phoenix Area ThreadEx 120 BUCKEYE 5N COOP 119 BULLHEAD CITY COOP 116 EAST MESA COOP 116 LAKE HAVASU CITY COOP 115 Lake Havasu City Area ThreadEx 115 Phoenix lead in 80° minimums at 102. Data for January 1, 2024 through September 18, 2024Click column heading to sort ascending, click again to sort descending. PHOENIX AIRPORT WBAN 102 Phoenix Area ThreadEx 102 MESA FALCON FIELD WBAN 91 BULLHEAD CITY COOP 86 SCOTTSDALE MUNICIPAL AP WBAN 84 SMITH PEAK ARIZONA RAWS 84 LAKE HAVASU CITY COOP 83 Lake Havasu City Area ThreadEx 83 YOUNGTOWN COOP 78 YUMA PROVING GROUND WBAN 77 YUMA MCAS WBAN 75 Yuma Area ThreadEx 75 BUCKEYE 5N COOP 72 AJO COOP 71 PHOENIX DEER VALLEY MUNICIPAL AP WBAN 70 3 1 Link to comment Share on other sites More sharing options...
Typhoon Tip Posted September 18 Share Posted September 18 On 9/16/2024 at 7:06 PM, GaWx said: The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%: https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population there's a lot of urban layouts across the continent that have not arrived through time with as much expansion, where also observing proportionate gains in t averages ( relative to their specific climate). the idea should be consistent in the integral of the curve - which it is not. in other words, the rises have been ubiquitous, while the rate of urban expansion was too variable to logically conclude hi effects 'as much'. i did not say phx's growth in that respect is no factor. no issue with that. what i said was, it's mostly climate change. and it has to be anyway, because the climate provides the environment for the uhi feedback - not the other way around i might be mistaken here but i suspect folks are thinking that the consiliency of cc is actually not considering the urban heat island in the data ? no 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 18 Author Share Posted September 18 2024 was the first year that saw large or major U.S. population centers affected by extreme duration heatwaves (100 or more consecutive days with 100° or above high temperatures). East Mesa and Phoenix, both of which are the only population centers with 250,000 or more people to experience such streaks went on to record 113 consecutive 100° or above highs. The list for 110+ such consecutive days is below. 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 19 Author Share Posted September 19 Phoenix has seen 120 100F (37.8C) or hotter days this year (tied for 8th highest with 1992). Phoenix will very likely reach or exceed 125 such days for the second consecutive year. There has never been 2 consecutive such years. 130+ days is possible. 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 23 Author Share Posted September 23 The latest guidance suggests that Phoenix will experience its hottest last week of September on record. Select record heat statistics for the last week of September are below. 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 26 Author Share Posted September 26 Phoenix is in the early stages of an unprecedented last week of September heatwave. This heatwave occurs as Phoenix is experiencing a warming climate. The second half of September has been warming rapidly (4.4F/2.4C from 1961-1990 to 1991-2020). The distribution of 100F (37.8C) and 105F (40.6C) or above readings has risen. 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted September 29 Author Share Posted September 29 Phoenix set a new all-time September monthly record high temperature today. The high was 117F, which matched the August monthly record. 3 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 1 Author Share Posted October 1 Phoenix experienced its hottest last week of September on record. No past last week of September heatwave was comparable. In fact, the 2024 heatwave was so extreme that it exceeded a synthetic heatwave constructed from all the pre-2024 daily record values for the September 24-30. The average 111.6° high temperature was the highest for any 7-day period in September. Prior to 2024, the hottest average maximum temperature was 109.6° from September 1-7, 1945. September 4-10, 2024 beat that mark with a 111.1° average. September 24-30 exceeded that new mark. 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 1 Author Share Posted October 1 2024 has been a marathon of heat in Phoenix. Following the hottest summer on record, Phoenix experienced its hottest September on record as the heat persisted. September 2024’s monthly mean temperature of 94.6° crushed the old record of 92.2° that had stood since 2001. September started with its hottest first week on record (mean temperature: 99.3° vs. the old record of 98.2° from 2019). It concluded with its hottest last week of the month (mean temperature: 97.1° vs. 92.0°, 2015). June-September 2024 was also the hottest June-September on record with a four-month mean temperature of 97.9°. That smashed the record of 95.6° that was set just last year. September highlights included a new September monthly high temperature record (117°), a new record high September low temperature (93°), a new September record high daily mean temperature (102.0°), and the conclusion of a record 113-day stretch during which the temperature rose to 100° or above on each day (old record: 76 days). Anthropogenic climate change amplified by the urban heat island effect is driving a warming of Arizona’s and Phoenix's summers and Septembers. A potential key mechanism by which climate change drives extreme events involves the increased frequency of quasi-resonant amplification (QRA) events. QRA events result in persistent summer extreme events, including heatwaves, in the Northern Hemisphere (Guimarães et al., 2024). QRA events likely contributed to recent persistent and often extreme heat in parts of North America (including the Phoenix area), Europe, and Asia. Currently, the normal September mean temperature (1991-2020 baseline) is 89.2°. That exceeded the 30-year average value for August 1939-1968. The warming has been especially pronounced during the second half of September. Between 1961-1990 and 1991-2020, the September 1-15 mean temperature rose 2.9° from 88.1° to 91.0° with the first week warming 3.3° from 89.1° to 92.4°. During the same periods, the September 16-30 mean temperature rose 4.4° from 82.9° to 87.3° with the last week warming 4.5° from 82.1° to 86.6°. Since record keeping began in August 1895, 8 of the 11 (73%) last weeks of September with mean temperatures of 90.0° have occurred since 2000 and all have occurred since 1989. Six (55%) of those weeks have occurred since 2010 and three (27%) have occurred since 2020. 1 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 1 Author Share Posted October 1 For some measure of how extreme and abnormal the heat in Phoenix has been this year, just last year Phoenix recorded its hottest summer on record (surpassed this year). The three-month mean temperature for Summer 2023 was 97.1°. The four-month June-September 2024 mean temperature exceeded that mark, coming in at 97.9°. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted October 1 Share Posted October 1 15 hours ago, donsutherland1 said: ....the increased frequency of quasi-resonant amplification (QRA) events. QRA events result in persistent summer extreme events, including heatwaves, in the Northern Hemisphere (Guimarães et al., 2024). QRA events likely contributed to recent persistent and often extreme heat in parts of North America (including the Phoenix area), Europe, and Asia... the article contains a broader perspective but just wrt to the bold above: yup... i've been writing about this phenomenon - or trying to raise attention - as to the 'synergistic heat wave' one in the same. you get some kind of harmonic feedback from the environment that is also not very well understood and/or not necessarily built into the modeling/leading indicators ... boom! the event exceeds expectations. but i also believe it is not just feed back from the physical enviroment, but i also see atmospheric harmonics taking place too. like rogue waves in the ocean as analogy, where multi scaled waves come into a constructive interference - the degree of amplitude tends arrive large and there goes edmond fitzgerald. 2 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 2 Author Share Posted October 2 The ongoing historic late-season heatwave toppled October monthly records in parts of Arizona and California. Palm Springs reached the highest U.S. temperature on record for October. Link to comment Share on other sites More sharing options...
Typhoon Tip Posted October 2 Share Posted October 2 may not be appropriate for this thread ? japan set the 2nd warmest september since records began back in 1898 according to the meteorological agency. "But some regions, including eastern and western parts of mainland Japan, logged the highest ever average temperatures for September since comparable data began available in 1946, the agency added." given to the damning global surgence of warmer than normal just about anything that can be defined, i feel that cited statement is probably more important than the fact that this particular september was "only" the 2nd warmest ever. a completely chaotic timed cloudy day comes along enough to hide a 10th of a degree and we're enabling deniers - ( https://phys.org/news/2024-10-japan-hottest-september.html ) 1 Link to comment Share on other sites More sharing options...
TheClimateChanger Posted October 2 Share Posted October 2 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 2 Author Share Posted October 2 18 minutes ago, TheClimateChanger said: Amber is a top-notch meteorologist. She has done a terrific job conveying both the forecast to her viewers and the reality that what is taking place is being driven by climate change. She's a real asset to the Phoenix community. Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 2 Author Share Posted October 2 The high temperature of 117° on September 28, 2024 set a new monthly record and matched the August monthly record. It was so extreme for the second half of September that i fell well outside what statistically would be expected using a 99.9% confidence interval based on 30-year moving average September 16-30 high temperatures. The October 1, 2024 113° high temperature, which demolished the prior October record of 107° (October 1, 1980, October 2, 1980, and October 1, 2020) was so extreme that it falls outside of what would statistically be expected using a 99.9% confidence interval based on 30-year moving average October high temperatures. Although the charts start at 1970 for easier viewing, 2024 is the only year in Phoenix's climate record (October 1895-present) that saw the September 16-30 and October monthly high temperature break out of their 99.9% confidence intervals. Separately, both July 2023 and July 2024 broke out of the same confidence interval for monthly average temperatures. Further, during the 7-day September 25-October 1, 2024 period, Phoenix has had an average high temperature of 112.3°. The previous record high average maximum temperature during the September 25-October 1 period was set in 2010. That average was 104.9°. Phoenix has never experienced a late-season heatwave like the current one. And Phoenix wasn't alone with extreme heat on October 1st. Blythe, Palm Springs, Tucson, and Yuma were among cities that set new monthly records. At Palm Springs, the temperature reached 117°, which tied the U.S. national October record high temperature. 1 Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 3 Author Share Posted October 3 The ongoing historic late-season heatwave in Arizona is unprecedented in the State's climate record. The 9-day period has set state records for highest average high temperature, average low temperature, and average temperature for the September 24-October 2 period. All of those marks are at least 1°C (1.8°F) above their prior marks. Link to comment Share on other sites More sharing options...
donsutherland1 Posted October 4 Author Share Posted October 4 The heat so far in October has been made at least 5 times as likely by climate change in the Phoenix area and a large swath of the southwestern United States. Link to comment Share on other sites More sharing options...
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