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Old 01-01-2021, 04:01 PM
 
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Quote:
Originally Posted by jbgusa View Post
I think they should go to using a 50 or 60 year average. A lot less prone to being influenced by freak events.
Any evidence for that? I think freak events are likely to contribute a small part of of the variation between successive 30 year normals, as by definition freak events are rare and usually of short duration. An usually hot day or heavy downpour etc is going to have very little impact on averages of 30 years.
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Old 01-02-2021, 03:05 PM
 
Location: Fort Worth, Texas
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Online sources claim that the New climate normals won’t be published until May 2021.......
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Old 01-02-2021, 03:29 PM
 
Location: Live:Downtown Phoenix, AZ/Work:Greater Los Angeles, CA
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Quote:
Originally Posted by Isleofpalms85 View Post
Online sources claim that the New climate normals won’t be published until May 2021.......
Part of that is the use of 29 day smoothed averages, so December's data won't even be complete until the 15th of this month
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Old 01-02-2021, 04:40 PM
 
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Quote:
Originally Posted by FirebirdCamaro1220 View Post
Part of that is the use of 29 day smoothed averages, so December's data won't even be complete until the 15th of this month
How does that work and why? I assumed they'd just add up all the data for the month and divide it by the number of days.
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Old 01-02-2021, 04:58 PM
 
Location: New York Area
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Quote:
Originally Posted by Bisfbath View Post
How does that work and why? I assumed they'd just add up all the data for the month and divide it by the number of days.
That works for July and January, that's it. The temperature fluctuates too much any other month. The "smoothing" is so when you calculate your 30 year average, you don't get a mean high of 86° one day, 83° the next, 84° the next. With "smoothing" the mean high in NYC would be 84° from roughly July 10 to August 10, and a somewhat steady curve rising from 38° around the end of January until July 10. Otherwise it is hard for people to know a rough "normal" for any given day. One reason I would like to use a 50 or 60 year base is that I am suspicious of the drop in the 30 year average high during the period of roughly July 18 to July 25 in NYC from 86° to 84°.
Quote:
Originally Posted by Bisfbath View Post
Any evidence for that? I think freak events are likely to contribute a small part of of the variation between successive 30 year normals, as by definition freak events are rare and usually of short duration. An usually hot day or heavy downpour etc is going to have very little impact on averages of 30 years.
While I am a climate change skeptic I do not think we are cooling. I think the 1970's, 1980's and the 2000's both featured a bunch of cool summers that have skewed the current and previous 30 year averages. Worthy of note is that except for a couple of days in 1977, it never topped 100° from 1966 until 1980, and then not again until 1991. And 1969, 1971, 1972, 1974, 1975, 1976, 1979, 1981, 1984, 1985, 1986, 1989, 1990, 1992, 1996, 1998, 2000, 2003, 2004, 2008 and 2009 were quite cool, with few 90+ days.

The NYC "scorecard" for the 2010's is: hot - 2010, 2011, 2012, 2013, and cool, 2014, 2018 and 2019.


Where I may be wrong, however, is the growing vegetation near with Central Park station at Belvedere Castle; it looks like boreal forest there.

Last edited by jbgusa; 01-02-2021 at 05:09 PM..
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Old 01-02-2021, 09:52 PM
 
Location: Seattle area
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Quote:
Originally Posted by jbgusa View Post
That works for July and January, that's it. The temperature fluctuates too much any other month. The "smoothing" is so when you calculate your 30 year average, you don't get a mean high of 86° one day, 83° the next, 84° the next. With "smoothing" the mean high in NYC would be 84° from roughly July 10 to August 10, and a somewhat steady curve rising from 38° around the end of January until July 10. Otherwise it is hard for people to know a rough "normal" for any given day. One reason I would like to use a 50 or 60 year base is that I am suspicious of the drop in the 30 year average high during the period of roughly July 18 to July 25 in NYC from 86° to 84°.
Yea but that doesn't change the average high for the whole month, just the day to day averages.
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Old 01-03-2021, 12:22 AM
 
Location: New York Area
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Quote:
Originally Posted by Botev1912 View Post
Yea but that doesn't change the average high for the whole month, just the day to day averages.
True, but it's easier for the average member of the public to construe the average high during the period of mid-July to early August to be 77° rather than the jumpy graph if would otherwise be, or 32° for the mean for most of January. That's why the table is "smoothed." I don't think it's a bad approach but I think it should be for a longer period so that the period is not for statistical purposes influenced by even ten or so anomalous seasons. In a post a few above I have examples of a run of a few summers where New York barely hit 90°. In 2004 for example it hit 91° once in June, 90° once in August. In 2009 it hit 90° or better three days in April and three days in August, and June was about tied with 1972 for the coolest. In 2000 it it hit 90° or better three days in May, one or two days in June and one or two days in August. 2007 wasn't much warmer. 2003 and 2008 had extensive June heat waves, but little heat for the other parts of the summer. A thirty-year average can be misleading for long-term averages.
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Old 01-03-2021, 03:29 AM
 
992 posts, read 305,104 times
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Quote:
Originally Posted by jbgusa View Post
I think they should go to using a 50 or 60 year average. A lot less prone to being influenced by freak events.
Quote:
Originally Posted by jbgusa View Post
True, but it's easier for the average member of the public to construe the average high during the period of mid-July to early August to be 77° rather than the jumpy graph if would otherwise be, or 32° for the mean for most of January. That's why the table is "smoothed." I don't think it's a bad approach but I think it should be for a longer period so that the period is not for statistical purposes influenced by even ten or so anomalous seasons. In a post a few above I have examples of a run of a few summers where New York barely hit 90°. In 2004 for example it hit 91° once in June, 90° once in August. In 2009 it hit 90° or better three days in April and three days in August, and June was about tied with 1972 for the coolest. In 2000 it it hit 90° or better three days in May, one or two days in June and one or two days in August. 2007 wasn't much warmer. 2003 and 2008 had extensive June heat waves, but little heat for the other parts of the summer. A thirty-year average can be misleading for long-term averages.
Ah I see, I was thinking of monthly averages rather than daily ones. For climate, it's usually monthly stats that are used rather than daily ones. Or periods of three months.

The Australian BOM gives a good summary of climate normals and the reason to avoid overly-long reference periods:-


Statistics calculated over standard periods (commonly a 30 year interval) are often called climate normals, and are generally used as reference values for comparative purposes. The period is long enough to include the majority of typical year to year variations in the climate, but no so long that it is significantly influenced by longer-term changes in climate.


50 or 60 year normals i think would be significantly influenced by longer-term climate change for many locations and so be of less value in representing the climate as it is now, rather than that of the past.
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Old 01-04-2021, 04:59 AM
 
Location: Sydney, Australia
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Sydney's 1991-2020 climate normals are already on Wikipedia.

Here are the normals of my suburb in western Sydney:

Attached Thumbnails
A quick question in regards to the 1991-2020 climate normals?-untitled.jpg  
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Old 01-31-2021, 02:25 PM
 
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Default New normals for Indy

Quote:
Originally Posted by Isleofpalms85 View Post
Both Fort Worth Texas and Indianapolis Indiana are warmer and wetter overall in the 1991-2020 climate normals when compared to the 1981-2010 climate normals
Could you post the source? I'd be interested in seeing the new "official" monthly normals.
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