The charts today are all ones that have been used in the past, and since some of them can be complicated there will be links back to the original posts that have full explanations.
High Temperatures
Here we have the High temperatures for the year.
The colourful stuff in the background of this chart is the range of temperatures that have been recorded since 1996. The average high for each day is the white line in the centre; it is surrounded by a grey band for the 25th-75th percentiles (where temperatures will fall roughly half of the time); and outside of that are the warmest temperatures since 1996 in orange and the coldest in blue. And finally, the all-time warmest and coldest temperatures going back to 1880 are shown as the faint lines that are furthest from the average.
In 2017 we set four all-time records for warmest-High - on February 15, May 5, September 7 and September 11. If breaking 4 all-time records in one year sounds like a lot, we looked at that earlier this year in How Often Does Edmonton Break Temperature Records?
In addition to the all-time records, the orange dots in this chart also show warmest-since-1996 records, and there were 22 more of those. We didn't set any all-time records for coldest-Low (that doesn't happen very often), but we did set 15 coldest-since-1996 records which are shown by the blue diamonds. 3 of those were during the late-December deepfreeze, 5 were during the early-November coldsnap, and the rest were scattered throughout the year.
The Red & Blue highlighting in this chart shows days that were above or below average. With that we can see the many swings from coldsnap-to-heatwave (or visa versa) that happened in January, February, March, May, September, November and December.
Low Temperatures
Here we have the Low temperatures.
2017 set 6 all-time records for warmest-Lows, on May 5, June 8, August 21, August 28, September 8 and September 27. In addition to that there were 22 other warmest-since-1996 Lows, and 13 coldest-since-1996 Lows. 3 of those coldest-since-1996 Lows were between Christmas and New Year's, and 5 were in early-November.
How Normal is Average?
Looking at 2017's temperatures you might think that they bounced around from warmspells to coldsnaps, without much time spent at the average. And that's pretty typical.
This chart cycles through the High temperatures for the last 5 years, and we can see that every year spends a lot of time near the extremes. We looked at this in detail earlier this year in How Normal is Average? and saw that about 58% of the time we're within ±5°C of the average.
The Horserace
So how does 2017 compare to other recent years?
For a full explanation of this chart it's easiest to refer back to the original discussion of it in How warm is 2016? (September Edition). Generally though, it tracks how much warmer each day of the year was compared to the 20th century average - warm days get points and cold days lose them.
The blue and orange background is the range of all the years going back to 1880, and they are grouped together like that because showing each individual year gets too messy. To keep things simple the last 10 years are shown here as a reference.
So how warm was 2017? Using this metric it was Edmonton's 16th warmest-ever year. Recently 2015 and 2016 were both very warm, in 3rd and 4th spots respectively. 2017 falls well below them, but above every other year since 2007.
When we follow the red line we can sortof see all of the warmspells and coldsnaps: a bumpy January through May; a fairly steady climb through to September; a major dip for the unseasonably cold early-November; a climb back up during our December chinook; and then one final drop for the end-of-December deepfreeze.
Here we have one more summary of how 2017 breaks down, this time on a monthly basis. The full explanation of this chart was in How Warm is 2017 - the Months.
January was our most above-average month, at 5.4°C above the 20th century average. That's partly just luck though, because January started out a little cool, before finishing off warm, including 8 days above 5°C.
I say that January is lucky because many other months - February, March, November and December - also had heatwaves, but they were balanced-off by deepfreezes, and so when we look at the month as a whole the numbers are more moderate. December is still fresh in our minds, and the first 2 weeks were extremely warm, while the last week was very cold, and together those put December at 3°C above the 20th century average.
Warm & Cold Years
And all of that adds up to this chart, which is the full list of Edmonton's warmest and coldest years.
The explanation for this chart is in Edmonton's Warmest Years, but it is essentially averages all the temperatures for an entire year, and then compares that to the average for the 20th century. The reason I've used the 20th century average in several of the charts today is because this chart is based on one from the National Oceanic and Atmospheric Administration, and they use the 20th century average as their baseline.
2017 is in 16th place, overall and was 1.6°C warmer than the 20th century average. 2015 & 2016 were both warm El Niño years at 2.5°C and 2.9°C respectively, so 2017 is down from there. But it's just a bit below 9th and 10th place 2006 and 2005 at 1.9°C and 1.7°C, and 1999 was just a touch above it in 15th place.
This chart also shows the 5-year average, which really shot up in the mid-1970s and has stayed high ever since.
Really Cold Days
In terms of really cold days, 2017 had:
- 23 days with Low temperatures of -20°C or below (8 were in the last week of December)
- 11 at -25°C or lower (6 were in December)
- 2 at -30°C or lower (both in December)
And that's it for the 2017 Year-in-Review Part 1. Later this week in Part 2 we'll look at 2017's Precipitation.
No comments:
Post a Comment