Wednesday, 2 August 2017

Monthly Summaries

I will now be posting a monthly summary at the end of every month on my record books website. The link is below:

http://privaterecords.weebly.com/monthly-summaries

Please feel free to leave comments and suggestions in the comments section here or in the record books website.

Enjoy!

27 comments:

  1. Thank you JJ. I like the new summary section. So how many July's in history were colder and warmer than this one?

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    1. The average mean temperature was at the 36th percentile, which means that 36% of the years were as cold or colder than this one... Which is about 53 years because there are 145 years in the dataset. So this July was the 53rd coldest. If this is confusing, I could always revert to just saying ''53nd coldest'' instead of percentiles. The percentiles are just really good at showing how extreme the value was in the dataset.

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    2. Hi JJ. Personally I would prefer saying " 53rd coldest " it's your choice obviously but I just find is easier to understand that way. For a while it was looking like it would end up in the top 30 coldest until the late month heat wave.

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    3. Ok I will either have both or that simpler version. Thanks for the input.

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  2. Also, what is the outlook for August? I've been hearing talk of generally below normal temperatures into mid month. Summer is running below average so far correct?

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    1. At a quick glance, it appears the first half of the month will be colder than normal. There are hints of warming up in the second half but I want to wait and see before coming to any conclusions.

      The summer is finishing near to slightly below normal so far. June-July averaged 17.9°C, while the normal is 18.3°C.

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    2. Yeah it looks like below normal for the first half. I wonder if we will see an extended heat wave again in the second half. Hard to believe Fall will be setting in in a month from now. The tree across the street is already starting to drop a few leaves.

      I am curious about this, why have septembers warmed so much? I see they used to average around 11.5C and now they average 13.5C. Especially in the last 25 years they've been incredibly warm. Is there a reason this is happening? Is September going to become a summer month soon? Yet we rarely ever get a nice warm May anymore, except for 2016 which was a warm one. Mays usually are near to below normal. Is there any reason for this? It's almost like summers are shifting later into the year.

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    3. I don't know why Septembers have been warming so much. It seems summers have been extending later into the year like you say. It appears to be a widespread change, not just localized here.

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    4. Yes I see what you mean. Do you also agree they seem to be starting later too? Because we never get hot May's anymore either. Except for 2016, the trend has been towards colder mays in the last 2 decades or so.

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  3. US CPC outlooks continue to call for a warm fall, what is your take on this?

    I think it would be highly unlikely to get a fall and winter like 2015-16 and 2016-17. Both falls and winters were extremely warm. Statistically this shouldn't repeat itself for a third year. I'm hoping for a colder fall and winter. It seems falls are trending warmer this decade.

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    1. Yeah you're right, it would be unlikely to get a very warm fall for the third year in a row statistically. We certainly are due for a cold September as well, but the trend of late has been for warm Septembers. I personally lean toward a colder fall simply based on these stats. Other than that, I can't say what fall will bring. Seasonal forecasts are difficult.

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    2. Yes I understand the difficulty with seasonal forecasts. The weather network said last winter was going to be very cold but instead it finished 14th warmest. The trend does seem to be towards warmer falls but I honestly can't see this upcoming fall being as warm as the last two. I would like to see a cold September too.

      This summer has been interesting so far. June started off with record heat which progressed to record cold ( low maximum record ) in the second half of the month. We've had some pretty chilly nights this summer too. Yesterday dipped to 6C. This morning to 8C.

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  4. The interesting thing is that the extreme September warming didn't really start until around 2000. As that's when the black line on your graph starts going up. So in 17 years they've warmed an entire degree. Interesting. They were on a slow cooling trend until then.

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  5. JJ. Do you think we have the potential to reach a top 30 coldest summer? It would have been very likely if we didn't have the late July heat wave that brought the mean up quite a bit. But depending on the rest of August could we be looking at a top 30 coldest? The nights have been quite chilly so far this summer with a definite lack of humidity.

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    1. Yeah, the nights this August especially have been very chilly compared to normal. Only 3 of 13 days have seen lows above 10C. In fact, lows so far have averaged 9.1C up to today which would be in the top 10 coldest for August. I'll have to check this week about comparing to other first halves of August, because climatologically we usually don't get chilly like this until the second half of the month. At least afternoons have been warmer and this is expressed by the fact that the average mean for August so far is about 17.1C or so, which wouldn't even be in the top 30 coldest Augusts. As you mention, humidity has been low.

      The summer so far has averaged about 17.6C using the August mean up to today. This would not make it to the top 30 coldest summers, but would be the coldest summer since 2009. We'll have to wait and see how the second half of August changes the means...

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    2. I do enjoy the chilly nights. It looks like some much warmer nights are on the way though. I would like to see the summer place in the top 30 coldest though. I am surprised how cold the nights have been even though the days have been warm. Highs of 28/29 degrees during the afternoon. It feels like a nice early preview of fall though.

      The highlight of this summer has been the chilly nights. Daytime highs have been pretty average except for a very chilly second half of June.

      If it wasn't for the warm first half of June we'd be talking about a top 30 coldest guaranteed.

      What is the average summer mean temperature for a normal summer? I do suspect this summer will finish below normal unless we get really hot for the second half of August.

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    3. 30-year normal is 18.4°C.

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    4. Thanks!
      Does it look like we will be heading into a warmer pattern? It looks like the days of single digit nights are over for a while now. Very warm lows in the forecast. In fact a high of 32C on Saturday with a low of 20C

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    5. I haven't seen anything too strong to believe that we're heading into an extended period of heat but it does look like a warmer second half than the first half overall. That 20C low seems too high under current guidance. I wouldn't expect warm nights like that unless we had some strong winds overnight or some higher dewpoints creeping north.

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    6. Is that why they get warm nights south of the border is because they get higher dewpoints?

      Although I don't think a high dew point is necessary for a warm night. On the night of July 11/12 1936, during Winnipeg's worst heat wave ever, the minimum was an unbelievable 28.3C with the temperature at or above 30C for most of the night. It has been said that it was very dry to allow temperatures to reach the 40s like they did. So how would a night stay that warm without high dewpoints?

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    7. Cloud cover and gusty winds at night can also keep temperatures warmer at the surface. A thorough explanation can be seen here if you want to know more https://courseware.e-education.psu.edu/courses/meteo101/Section4p05.html. Also, we don't have access to dewpoint observations from 1936 so we can't say for sure that it wasn't humid on some days. There was a 44 mm rainfall the day after that 28C low, which was likely thunderstorm-related, so there was definitely some humidity to play with. But in general, it was probably a very dry month, because it is extremely difficult to get to 37-42C with high humidity.

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    8. Thanks!

      Why did they not start taking dewpoint, hourly temp observations, humidex and windchill values, or thunderstorm data until the 1950's? Is there a specific reason they didn't take this starting in 1872?

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    9. Some measurements, like wind (and therefore humidex and wind chill) (I'm not sure about others like dewpoint etc.), were taken as early as the 1920s. However, they have not been digitized (only available in hard-copy format) and are sitting somewhere (might be Western University in Ontario or somewhere else, I'm not entirely sure).

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    10. (and therefore humidex and wind chill)... shouldn't have included humidex there because it requires dewpoint.

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    11. I'm surprised they haven't put the measurements in the online databases then. It would be interesting to see those wind chills.

      Did they not have the technology to measure dewpoint back then?

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  6. JJ how is our outlook into early September looking?

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    1. Looks like a near normal to warmer than normal end to August then likely increasingly variable in September as is typical with fall. If August finishes below normal, it will be the 4th consecutive below normal month. Appears we have entered into a drier and cooler weather pattern and at this point it doesn't appear it should change much in the near future. However, we haven't had a truly colder than normal September since the 1990s, so I hope this trend continues into this year.

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