Anchorage's Record-Breaking Summer of 2019

[donsutherland1]

Notes: This post was prepared in scientific style to provide links to key points in the section on climate change. All temperature data is from the National Climatic Data Center. The EPO data is through August 29.

OVERVIEW

Prior to 2019, July 2016 was Anchorage, Alaska's warmest month on record. Summer 2019 was even warmer than July 2016.

A warm synoptic pattern that occurred within the context of increased anthropogenic greenhouse gas forcing resulted in exceptional and persistent record-breaking warmth this summer. During June-August 2019, Anchorage experienced its warmest summer on record by 2.0°F (1.1°C). Its summer mean temperature (62.815°F/17.119°C) exceeded that of its warmest month on record prior to 2019 (62.694°F/17.052°C in July 2016).

Summer 2019 saw Anchorage record its warmest-ever June, July, and August. Anchorage tied its all-time record high minimum temperature on two consecutive days. Anchorage reached 90°F (32.2°C) for the first time on record. The duration of the excessive warmth and extreme temperatures recorded during the summer would have been very unlikely, if not improbable, without human-induced climate change.

PREDOMINANT SYNOPTIC PATTERN

Summer 2019 featured a remarkable coupling of atmosphere and ocean. A persistent upper air ridge that promoted warm and dry conditions was anchored over the waters with the highest sea surface temperature anomalies.

These conditions promoted a synoptic pattern where the East Pacific Oscillation (EPO) was negative. The negative EPO combined with a negative Arctic Oscillation (AO) to form a negative Arctic Oscillation-negative EPO pattern (AO-/EPO-) that predominated during the summer. During summer 2019, the AO was negative on 81/92 (88%) days. The EPO was negative on 64% of days.

An AO-/EPO- pattern is typically a warm one in Anchorage. For the current climate reference period (1981-2010), the average summer temperature in Anchorage was 56.9°F (13.8°C). During AO-/EPO- patterns, the average was 57.6°F (14.2°C). Climate change has led to summers becoming warmer and also warm synoptic patterns (AO-/EPO-) becoming warmer.

ROLE OF CLIMATE CHANGE

The observed global warming since the 1950s is unequivocal with anthropogenic greenhouse gas emissions being the dominant driver of that warming (IPCC Climate Change Synthesis Report 2014). The warming is a global phenomenon with 98% of the world having experienced its warmest 51 years during the current 2,000 years (Neukom, et al. 2019).

Since 1880, Arctic temperatures have been increasing at more than twice the rate of global temperatures (GISTEMP Data Set). In recent decades, the rate at which the Arctic has been warming relative to worldwide temperatures has increased. From 1980 through 2018, the Arctic has warmed at a decadal rate of 1.51°F (0.84°C), which is just over 3.5 times the global rate (GISTEMP Data Set). Multiple lines of evidence corroborate the rapid warming that is taking place in the Arctic. Increases in humidity, precipitation, river discharge, glacier equilibrium line altitude and land ice wastage; warming of near-surface permafrost; and, decreases in sea ice thickness and extent, and spring snow cover extent and duration are consistent with rising temperatures (Box, et al. 2019).

Consistent with the Arctic warming, Alaska has recently experienced temperatures that are warmer than they have been at any time in the past century (Thoman et al., 2019). As Alaska has warmed, Anchorage has also experienced rising temperatures. A disproportionate share of Anchorage's warmest months has occurred in 2000 or later.

During the 1961-1990 base period, Anchorage had a summer (June 1-August 31) mean temperature of 56.4°F (13.6°C). During the current climate reference period (1981-2010), Anchorage's average summer temperature had risen to 56.9°F (13.8°C). For the most recent 30-year period (1989-2018), Anchorage's average summer temperature had increased further to 57.6°F (14.2°C). The last time Anchorage had a cooler than normal summer (mean temperature below the 1981-2010 reference period) was 2012 when the average summer temperature was 56.0°F (13.3°C).

Without climate change, the extreme summer 2019 warmth would have been improbable. However, the combination of a rising average summer temperature and increasing variability (1961-1990: mean temperature 56.4°F/13.6°C; standard deviation: 1.4°F/0.8°C vs. 1989-2018: mean temperature: 57.6°F/14.2°C; standard deviation: 1.6°F/0.9°C) has made summers like 2019 approximately 190 times more likely than they had been.

The long duration of the AO-/EPO- synoptic pattern led to the relentless persistence of above to much above normal temperatures in Anchorage that allowed monthly warm temperature records to be set in June, July, and August. Rapid Arctic warming has contributed to an increasing frequency of long-duration upper air patterns (Francis, et al. 2018). Should the world warm 3.6°F (2.0°C) above its pre-industrial temperatures, the persistence of boreal summer weather will likely increase further (Pfleiderer, et al. 2019).

Based on the above evidence, human-driven climate change played a key role in bringing about Anchorage's historic summer warmth. Without anthropogenic warming, the combination of the exceptional heat and remarkable duration of the warmth in Anchorage would have been very unlikely, if not improbable.

DATA AND RECORDS

Summer 2019 Temperature Thresholds:

Lows 60°F (15.6°C) or above: 9 days (previous summer and annual record: 4, 2016)

Highs 70°F (21.1°C) or above: 49 days (previous summer record: 40, 2004; previous annual record: 42, 2013)

Highs: 80°F (26.7°C) or above: 8 days (previous summer and annual record: 4 days, 2015)

Highs: 90°F (32.2°C) or above: 1 day (none prior to 2019)

Daily Record High Minimum Temperatures:

June 8: 54°F (12.2°C) (old record: 53°F/11.7°C, 1978)

June 24: 58°F (14.4°C) (tied record set in 1984)

June 28: 57°F (13.9°C) (old record: 56°F/13.3°C, 2015 and 2016)

June 29: 60°F (15.6°C (old record: 58°F/14.4°C, 1984 and 1990)

June: 3 new records and 1 tied record

July 2: 57°F (13.9°C) (tied record set in 1970)

July 3: 58°F (14.4°C (tied record set in 1979 and tied in 1999 and 2014)

July 5: 61°F (16.1°C) (old record: 60°F/15.6°C, 1984)

July 6: 59°F (15.0°C) (tied record set in 2015)

July 8: 61°F (16.1°C) (old record: 59°F/15.0°C, 1968, 2003, and 2004)

July 9: 62°F (16.7°C) (old record: 59°F/15.0°C, 2003)

July 12: 60°F (15.6°C) (old record: 59°F/15.0°C, 1977)

July 13: 59°F (15.0°C) (tied record set in 1972 and tied in 2013)

July 20: 59°F (15.0°C) (old record: 58°F/14.4°C, 1973, 1983, 2003, 2004, and 2016)

July 22: 58°F (14.4°C) (tied record set in 1984 and tied in 1996, 2013, and 2016)

July 24: 59°F (15.0°C) (tied record set in 1984)

July: 5 new records and 6 tied records

August 7: 61°F (16.1°C) (old record: 58°F/14.4°C, 1979 and 1983)

August 13: 63°F (17.2°C) (old record: 57°F/13.9°C, 2003) ***tied all-time record***

August 14: 63°F (17.2°C) (old record: 58°F/14.4°C), 2001) ***tied all-time record***

August 16: 58°F (14.4°C) (tied record set in 1967)

August 17: 57°F (13.9°C) (old record: 56°F/13.3°C, 1984)

August: 4 new records and 1 tied record

Summer: 12 new records and 8 tied records

Daily Record High Maximum Temperatures:

June 23: 78°F (25.6°C) (old record: 75°F/23.9°C, 1974)

June 24: 75°F (23.9°C (old record: 74°F/23.3°C, 2015)

June 27: 79°F (26.1°C) (old record: 78°F/25.6°C, 1997)

June 28: 81°F (27.2°C) (old record: 80°F/26.7°C, 1997)

June 29: 82°F (27.8°C) (old record: 77°F/25.0°C 1968, 1989, and 1990)

June: 5 new records

July 3: 80°F (26.7°C) (tied record set in 2018)

July 4: 90°F (32.2°C) (old record: 77°F/25.0°C), 1999) ***all-time record***

July 5: 81°F (27.2°C) (old record: 77°F/25.0°C, 1999)

July 6: 81°F (27.2°C) (tied record set in 2015)

July 7: 85°F (29.4°C) (old record: 79°F/26.1°C, 2009)

July 8: 85°F (29.4°C) (old record: 84°/28.9°C, 2003)

July: 4 new records and 2 tied records

August 7: 77°F (25.0°C) (tied record set in 2015)

August 10: 77°F (25.0°C) (old record: 75°F/23.9°C, 1960, 1972, and 2004)

August 12: 77°F (25.0°C) (tied record set in 2005)

August 13: 77°F (25.0°C) (old record: 75°F/23.9°C, 1963, 1977, 2007)

August 14: 75°F (23.9°C) (old record: 74°F/23.3°C, 1990)

August 15: 77°F (25.0°C) (old record: 76°F/24.4°C, 1984)

August: 4 new records and 2 tied records

Summer: 13 new records and 4 tied records

CONCLUSION

Anchorage experienced a historically warm summer. The all-time record high temperature was established, the all-time record warm minimum temperature was tied on two consecutive days, and numerous daily record high maximum and minimum temperatures were set or tied. June 2019 was the warmest June on record. July 2019 was the warmest July and month on record. August 2019 was the warmest August on record.

Ocean-atmosphere coupling produced a persistent pattern associated with warmer than normal temperatures. Anthropogenic climate change, that has driven global and Arctic warming and led to increasing temperature variability in the Arctic region, has dramatically increased the probability of persistent warmth and extreme high temperatures. Absent the contribution of climate change, the kind of warmth seen during summer 2019 was extremely unlikely, if not improbable.

Going forward, the ongoing warming is likely to continue on account of a continuing rise in the atmospheric concentration of greenhouse gases. Although summer warmth equivalent to 2019 will likely remain rare over the next decade or two, the probability of such occurrences will very likely increase.

[Typhoon Tip]

What really needs to be done is a deeper statistical analysis of past -AO summers. A good start; of the three 'hot months,' June, July, and August, when ever the three averaged negative in the Northern Annual Mode, what were the temperature anomaly distributions those years, both as scalar values, but also relative to the oscillation's SD curves.  

That kind of analysis might begin to expose a secondary trend ... revealing at least the plausibility of systemic change ( the elephant in the room .. notwithstanding), change too often lost in the din of climate noise. 

For example, suppose there was a -.5 SD mean in the AO in 1955, and the hemispheric temperatures were X.   

Then, in 2019, there was a -.5 SD mean, and the hemispheric temperatures were Z   ... 

( X - Z ) = some positive or negative value that in fairness, may not mean much? 

However... if this were expanded to a bigger comparative population,  such that utilizing (x̄ - ȳ),

 ... where (y₁+ y₂+ ... + y_n)/n = ȳ and the same for x̄ ... if the result equaled a positive number, that is a better finger-print for actual change..  I'm sure this sort of number juggling is being performed everywhere there is a reputable scientific process focused in environmental/atmospheric research/problem solving, but for some reason, I haven't found any published research that specialized in a relative AO to temperature anomaly distribution approach like that ... as a 2ndary precipitant study that might help to crystalize an image through the obfuscating blur of anomalies ( often used to hide truths and lies  eh hm ).     

Primer:    ... Negative NAMs correlate with warm temperature anomalies above the (*) 60th parallel. During those periods,  (**) cool temperatures tend to occur below the 60th parallel, known as mid latitudes. Naturally, this overall pattern/distribution of temperature anomalies above and below the 60th parallel ... reverses during positive Annular Modes. 

( * that ~ demarcation of latitude around the hemisphere does not take into account topographical/geologic imposing variances, and also, fluctuates higher and lower in latitude depending upon the season).

( ** relative to normal AND "pattern" ...a latter distinction often lost and/or strategically elided in efforts of deniers, as well as less learned in general. Relativity matters... a warm pattern may be so warm in 1900, and that same pattern may be cooler(warmer) at another time and space of different geological/environmental arena, a.k.a., the European heat waves now, versus similar pattern manifestation back whence).

This has been a rather robustly +AO(NAM) summer.  The Alaskan warm summer ... really should be compared to past positive annular mode summers, and also, other northern latitude/geographies around the hemisphere compared.  Intuitively ...this is almost tongue-in-cheek and anyone objective has a pretty solid idea what the results are likely to look like ...Oh, some value of positive across the board, where -1 SD summer ins 1890' did not produce the same wamrth as this year...and so forth, but, taking a study through the arithmetic caries more weight for everyone save the eerily growing numbers of population that as an entirely separate and sociological concern, have come under the impression that is okay to say and act in adversarial 'no' in the face of Universal fact(s), that the right to do so is merely enough to refute the reality the do not want to accept.

Very recently ( spanning the last two weeks ) the mode has been relaxing toward neutral/positive, and is forecast to continue to do so into September.  This is just a heads up; it's an intra seasonal ...at times, intra-weekly time-scale teleconnector, so this is not a statement/intention for seasonal forecast. 

[donsutherland1]

On 9/3/2019 at 9:23 AM, Typhoon Tip said:

What really needs to be done is a deeper statistical analysis of past -AO summers. A good start; of the three 'hot months,' June, July, and August, when ever the three averaged negative in the Northern Annual Mode, what were the temperature anomaly distributions those years, both as scalar values, but also relative to the oscillation's SD curves.  

That kind of analysis might begin to expose a secondary trend ... revealing at least the plausibility of systemic change ( the elephant in the room .. notwithstanding), change too often lost in the din of climate noise. 

For example, suppose there was a -.5 SD mean in the AO in 1955, and the hemispheric temperatures were X.   

Then, in 2019, there was a -.5 SD mean, and the hemispheric temperatures were Z   ... 

( X - Z ) = some positive or negative value that in fairness, may not mean much? 

However... if this were expanded to a bigger comparative population,  such that utilizing (x̄ - ȳ),

 ... where (y₁+ y₂+ ... + y_n)/n = ȳ and the same for x̄ ... if the result equaled a positive number, that is a better finger-print for actual change..  I'm sure this sort of number juggling is being performed everywhere there is a reputable scientific process focused in environmental/atmospheric research/problem solving, but for some reason, I haven't found any published research that specialized in a relative AO to temperature anomaly distribution approach like that ... as a 2ndary precipitant study that might help to crystalize an image through the obfuscating blur of anomalies ( often used to hide truths and lies  eh hm ).     

Primer:    ... Negative NAMs correlate with warm temperature anomalies above the (*) 60th parallel. During those periods,  (**) cool temperatures tend to occur below the 60th parallel, known as mid latitudes. Naturally, this overall pattern/distribution of temperature anomalies above and below the 60th parallel ... reverses during positive Annular Modes. 

( * that ~ demarcation of latitude around the hemisphere does not take into account topographical/geologic imposing variances, and also, fluctuates higher and lower in latitude depending upon the season).

( ** relative to normal AND "pattern" ...a latter distinction often lost and/or strategically elided in efforts of deniers, as well as less learned in general. Relativity matters... a warm pattern may be so warm in 1900, and that same pattern may be cooler(warmer) at another time and space of different geological/environmental arena, a.k.a., the European heat waves now, versus similar pattern manifestation back whence).

This has been a rather robustly +AO(NAM) summer.  The Alaskan warm summer ... really should be compared to past positive annular mode summers, and also, other northern latitude/geographies around the hemisphere compared.  Intuitively ...this is almost tongue-in-cheek and anyone objective has a pretty solid idea what the results are likely to look like ...Oh, some value of positive across the board, where -1 SD summer ins 1890' did not produce the same wamrth as this year...and so forth, but, taking a study through the arithmetic caries more weight for everyone save the eerily growing numbers of population that as an entirely separate and sociological concern, have come under the impression that is okay to say and act in adversarial 'no' in the face of Universal fact(s), that the right to do so is merely enough to refute the reality the do not want to accept.

Very recently ( spanning the last two weeks ) the mode has been relaxing toward neutral/positive, and is forecast to continue to do so into September.  This is just a heads up; it's an intra seasonal ...at times, intra-weekly time-scale teleconnector, so this is not a statement/intention for seasonal forecast. 

I included a chart for AO-/EPO- summers (averages are based on all days that met both criteria). That historically warm pattern has also grown warmer.

[donsutherland1]

Utqiagvik (formerly Barrow) has seen a dramatic increase in the number of days each year where the temperature stays above freezing. Much of the increase has come recently, as summer Arctic sea ice has declined markedly from prior levels.

The change in the 30-year moving averages (to remove the noise of interannual variability) for the number of such days provides further illustration of the dramatic warming that is underway in the Arctic region.

For the 1961-90 base period, the 30-year moving average was 43.9 days. For the latest 30-year period (1989-2018), the moving average has increased to 63.4 days. That's a nearly 20-day increase over a remarkably short period of time. Through September 3, Utqiagvik has had 76 days with temperatures above freezing. The last time Utqiagvik had fewer than 50 days above freezing was 2003.

In 2007, the minimum Arctic sea ice extent fell below 5 million square kilometers for the first time (JAXA data set). Since then, only 2009 has had a minimum extent of 5 million square kilometers (5.054 million square kilometers). As of September 3, Arctic sea ice extent was 4.175 million square kilometers. During the "low ice" era that commenced in 2007, Utquiavik has averaged 76.8 days per year (2007-18) with above freezing temperatures.

Through September 3, Utqiagvik had a record 70 consecutive days where the temperature has stayed above freezing. The old record was 68 consecutive days from July 1-September 6, 2009. Prior to 2009, there were no cases with 60 or more consecutive days above freezing.

[donsutherland1]

Quick update for the larger June 1-September 15 period for Anchorage:

2019 had a mean temperature of 62.0°F (16.7°C). That surpassed the previous record warm figure of 60.0°F (15.6°), which was set in 2016.

The 10 warmest June 1-September 15 timeframes occurred as follows:

Prior to 1980: 2 cases
2000 or later: 7 cases
2010 or later: 5 cases
2015 or later: 4 cases

 

[donsutherland1]

Yesterday, Utqiagvik (formerly Barrow) experienced its first freeze of the season. That was its latest freeze on record. The prior record was September 7, 2009. As a result, that city's 85-consecutive day stretch above freezing ended. The old record was 68 consecutive days, set in 2009. Both records are likely, in large part, due to low Arctic sea ice.

[iluvsnow]

Well there's no lack of cold in Alaska now.....its weather....it happens.

[etudiant]

3 hours ago, iluvsnow said:

Well there's no lack of cold in Alaska now.....its weather....it happens.

While that is a forecast for Jan 1-6 of 2020, not of the temperatures now, it is pretty chilly already, with Fairbanks around 25 below zero F. Quite a swing from earlier.

 

[donsutherland1]

Less than 2 years after Anchorage’s historic  summer, Anchorage has recorded its earliest streak of 8 consecutive 70-degree days (May 27-June 3). The prior record was set during June 26-July 3, 2019. Today’s preliminary 78-degree high was the earliest such temperature on record. The previous mark was set on June 10, 1995.

Meanwhile, Juneau saw its earliest 3 consecutive 80-degree days (June 1-3). The old record was set during June 5-7, 1980.

[StormchaserChuck!]

Recent, weak -EPO that popped up recently, and none for many consecutive months going back to Oct 2021. (15 seconds to go through)

[donsutherland1]

Anchorage just experienced its warmest first five days of June on record. The mean temperature of 63.6° surpassed the old mark by 3.1°. Some charts:

 

 

 

 

[StormchaserChuck!]

Yeah, you just figure "it should be warmer here"

[donsutherland1]

Anchorage recorded its warmest first week of June on record:

Mean temperature: 62.1° (old record: 59.7°, 1997)

Average high: 72.3° (old record: 70.0°, 1996)

Average low: 51.9° (old record: 51.3°, 1990)