Wednesday, 2 September 2015

England/Wales v CONUS temperatures

Having digested overseas climate in recent years, I noted the record-warm January 1880 over the eastern US as exceptionally dry and cold over Western Europe – although similarly dry months there are not necessarily hot as far west as the US.

It is well-known that the contiguous US (CONUS) is by areal average much hotter than England and Wales in the northern summer, and colder in the winter. What I will try to do here is see how much variation there is between these normals, since the annual temperature means overlap somewhat. Since the CONUS averages a little hotter than England and Wales over the whole year, I will take positive as meaning the CONUS is hotter, negative that the CONUS is cooler than England and Wales.

Data exist for the years from 1895 to 2014, and I will do figures for fiscal year (July to June) as well as temperature. Fiscal year should provide a better picture than calendar year due to the greater influence of winter temperatures an annual variation, avoiding situations where unusually cold or warm winters are divided between two years.

Month # CONUS hotter # CONUS cooler Year of “highest” departure Year of “lowest” departure
July 120 0 1954 +17.94˚F
1983 +6.89˚F
August 120 0 1922 +16.33˚F
1997 +5.72˚F
September 120 0 1931 +15.43˚F
2006 +1.06˚F
October 108 12 1931 +8.72˚F
1969 -4.37˚F
November 29 91 1915 +6.07˚F
1951 -9.22˚F
December 3 117 2010 +1.73˚F
1924 -16.65˚F
January 0 120 1941 -0.70˚F
1930 -18.54˚F
February 8 112 1991 +5.83˚F
1903 -16.36˚F
March 45 75 1910 +6.46˚F
1912 -9.20˚F
April 114 6 1986 +10.42˚F
2007 -1.62˚F
May 120 0 1902 +13.97˚F
1917 +0.09˚F
June 120 0 1977 +16.38˚F
1976 +5.2˚F
Fiscal year 118 2 1962/1963 +5.40˚F
1911/1912 -0.37˚F

It can be observed that some extremes, noted in red above, seem to be systematically influenced by man-made greenhouse gas emissions.

Although I could use an earlier date since rainfall records in the southern hemisphere indicate man-made global warming (countered in the northern hemisphere by short-lived aerosol pollution) was taking control of the climate as early as 1967, I will use the 1980 Lonie Report – which paved the way for major expansion of polluting freeways in by far the planet’s worst greenhouse polluter (Australia) – as a cut-off for “natural” variability. Previous records for those established since are:
  • July “lowest”: 1976 (CONUS averaged 72.90˚F or 22.72˚C; CET was 18.7˚C or 65.66˚F)
  • August “lowest”: 1975 (CONUS averaged 71.53˚F or 21.96˚C; CET was 18.7˚C or 65.66˚F)
  • September “lowest”: 1949 (CONUS averaged 63.73˚F or 17.63˚C; CET was 16.3˚C or 61.34˚F)
  • April “lowest”: 1944 (CONUS averaged 48.97˚F or 9.43˚C; CET was 10.2˚C or 50.36˚F)
  • December “highest”: 1933 (CONUS averaged 36.43˚F or 2.46˚C; CET was 1.3˚C or 34.88˚F – though Scotland was actually milder than England or the CONUS)
  • April “highest”: 1908 (CONUS averaged 52.75˚F or 11.53˚C; CET was 6.0˚C or 42.8˚F)
  • February “highest”: 1954 (CONUS averaged a record 41.11˚F or 5.06˚C; CET was 2.6˚C or 36.68˚F)
Temperature for the winter of 1916/1917. Note the uniform cold over most of the northern hemisphere apart from the subtropics, Central Asia, Greenland and Sakhalin.
The case of May 1917, after a very long and severe winter across the northern hemisphere apart from Central Asia and Greenland (à la January 1963) is amazing. The month was by mean percentile (as opposed to temperature) easily the coolest every observed across North America. At 55.13˚F or 12.85˚C, May 1917’s mean temperature stands 5.06˚F or 2.8˚C below the virgin mean, and only May 1907 comes within 2˚F (1.1˚C) in terms of coolness.The pattern from the winter of 1916/1917 persisted remarkably through the spring, as can be seen below, although England and parts of southwestern Canada would come out slightly hotter than normal if something closer to the virgin mean were used:
Temperature anomalies for May 1917. Note the extreme and uniform cool over North America, Australia, East Asia and and eastern Europe
What’s more amazing is that no district in the contiguous US ranks higher than 41st coolest for the month, although it was not especially wet (very dry in the north). In fact, only the mid-Atlantic region (in 1967) the central-west coast (in 1933) and the Great Basin (in 1953) has widely experienced a record cool May since.
Rankings for May 1917 in the contiguous US. With over 87 percent in the “very cool” category this month is by mean temperature percentile by far the coolest from coast to coast.
In fact, May’s case of the CONUS being as cool as England and Wales during what is almost summer is much more exceptional than January 1880. Although accurate data do not exist, it is almost certain that in January 1880 the United States was around 2˚C (3.6˚F) hotter than England and Wales. Most places east of the Rockies averaged 9˚F or 5˚C above normal, and even the Pacific Northwest which received snowfalls comparable to the record cold January of 1950, was slightly milder than normal – though Canada was extremely cold.
Mean temperatures for January 1880, the most recent January where the CONUS averaged hotter than England and Wales (it’s a pity I can’t obtain figures relative to a mean less influenced by Australian greenhouse gas emissions, which would not show the western US as substantially cooler than average).
February 1954 was globally an exceptional month, notable for the complete lack of monsoonal rainfall over northwestern and central-western Australia (before CFCs and Australian coal power and freeways spread the monsoon far beyond its natural domain!) and for a major cyclone on the east coast that saw some of the heaviest rainfalls recorded in the world. Lismore record 480 millimetres or 18.90 inches in two days, and at Dorrigo Post Office a daily fall of 774.7 millimetres (30.50 inches) is generally regarded as an NSW record. The Macleay River was thirty feet (nine metres) deep as it raced through Kempsey.
Rainfall over Australia, February 1954. Note the extreme dryness over WA, where essentially no rain fell south of the Kimberley – then affected by a four-year drought of a type unknown to its present inhabitants.
February 1954 was exceptionally cold over Alaska, Central Asia and southeastern Europe. The extreme cool over eastern Australia is clearly due to the nonexistent monsoon over the northwest allowing anticyclones over the Bight to drive cool southerly air far inland. The month, however, was remarkably hot over the United States and south-of-treeline Canada: apart from perhaps March 1910 or October 1947, no pre-Lonie Report month matches February 1954 for average mean monthly temperature percentile over the CONUS, with the first and last weeks seeing shorts temperatures as far north as the border. It was also warm over eastern Greenland, the Sea of Okhotsk and the extreme north of Russia.
October 1969 is a striking month, which I have long known in Australia as the driest October in Perth and Adelaide, but a very wet month in northern New South Wales with Gilgandra under water from its biggest flood since 1956.
Rainfall over Australia for October 1969. Note the heavy rainfall over northeastern NSW and southeast Queensland, as well as over the wet-dry tropics (where it proved a false beginning and was followed by the last big wet season failure before Australian greenhouse emissions eliminated such occurrences.
Globally, October 1969 saw an “Indian summer” in England and the beginning of a warm winter in a cold era for Alaska, but cold weather in western Russia, South America and New Zealand as well as the contiguous United States:
March 1912 was the end of one of the most famous cold winters in the US – and a key part of one of only two years since 1895/1896 where the England averaged hotter than the contiguous US. It also saw a “March miracle” in Southern California, whereby Los Angeles, which had not seen rain for 49 days at February’s end and recorded just 1.60 inches (40.6 millimetres) between October and February, accumulated 8.65 inches in the next six weeks. San Diego had an amazing 20 wet days that March. In Britain, this March was very wet (top ten wettest since 1766) but extremely mild at 2.0˚C above the virgin mean and warmest since 1882. What’s notable on a broad scale about March 1912 is that the western ends of both main northern hemisphere continental landmasses were warm, but that the rest was uniformly very cold, suggesting two big blocking patterns were driving cold air into Canada, the contiguous US and Russia, whilst – as is typical during a Lower 48 cold wave – Alaska was unusually warm. Even with anthropogenic global warming have major impacts, Fairbanks has experienced only four milder Marches since and was as warm as Sioux City and 3˚F (1.7˚C) warmer than Helena, Montana.
The summers of 1954 for being cool and wet, and 1975 and 1976 for being hot and dry, are legendary in the UK. It’s interesting to see that these contrasting summers seem to have opposite-signed anomalies extending quite widely over the globe, and that 1954 appears to have a somewhat similar pattern to the fabled year of 1816, being very cool in Western Europe and hot in the east, though I have not checked how general this is for cool or wet English summers.
Although the summer of 1975 in the US is most famous for the northeastern heatwave that saw several New England states set still-standing temperature records (and it’s notable that Maine’s record of 105˚F or 40.6˚C comes from the very hot European summer of 1911), the two 1970s summers were generally very cool across the US. Indeed, the record July cool in Texas approaches that of 1993 in Idaho and surrounds for its exceptional character, with anomalies in maximum temperature as large as 9.6˚F or 5.3˚C below normal, so that it was sometimes hotter in England than in Texas!
This animation shows US temperatures during the hot and dry English summers of 1975 and 1976. It was notably cool in the West and South, where 1976 is the coolest calendar year since records begin.
The summer of 1954 – the coolest since 1907 in the UK – is famous for its severe southern heatwave and drought, likely related to a highly positive Atlantic Multidecadal Oscillation (AMO). July saw the hottest temperatures east of the Mississippi River, although the summer – like that of 1980 – was as cool over the Pacific Northwest as over Western Europe so it does not come out exceptionally hot over the CONUS as a whole:
Contiguous US temperatures for the summer of 1954. Note the unusual cool (and rain) over the Pacific Northwest and heat (and drought) over the Southern Plains
April 1944 was very cool in the US and also in most of Australia (in Melbourne it is the seventh coolest April since records began in 1855, whilst the West Central division of Kansas was equal coolest) but notably warm in Canada, western Siberia and western Europe. It does not appear as striking as previously reviewed months.
Global temperature anomalies for April 1944. Note the cool over Australia, Beringia and the central US, plus the heat over Western Europe that made Britain hotter than the CONUS.
April 1944 was also notable for being extremely wet – record floods on the Missouri occurred early that summer in Montana’s wettest month on record – and part of a very dry spring across Western Europe. In Victoria the autumn was wet between two record-dry seasons, but was a blip on the longest genuine drought during the period before Australia’s mining and road-building industries began to control the global climate.  
September and October 1931 were very hot over the interior US – the end of the great drought of 1930-1931 as November saw big rains:
The hot September and October of 1931 over the US – it’s a pity the colour was lost when I formed an animation!
February 1903 is one a of a number of months (the winter of 1948/1949 being outstanding in this line, as was January 1932) that was very cold over the western US, but mild over the eastern US and England. That winter was also the mildest over northern Japan until 1948/1949, and in fact February 1903 was one of the mildest on record over all of Russia west of the “cold pole”. It is remarkable for the heavy rains in the eastern US as well as England and extreme cold over the Southwest under a flow of Arctic air to the west of the cyclone:
This hopefully will be a good summary of CONUS versus CET temperatures, and a “big picture” look at some outstanding contrasts therein. I hope readers find these historical data of interest.

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