Saturday, December 2, 2017

November 2017 Summary

An average November for both temperature and precipitation

After the warmth of the last two months we finally experienced some cooler temperatures.  Overall, November was about half a degree cooler than average, but still within the average range (the last time we saw a month that was in the below average range was April 2016).

However, if you take a look at the temperature graph you can see that the 10th and 11th really stand out as abnormally cold days.  The temperature went down suddenly for about 36 hours and then just as suddenly came back up.  In fact, if you took out those two days the month would have ended up being a bit above average.

Although the 66.2 mm of precipitation was well below the average of 87.1 mm this was just enough to put November into the average range.  So going into the final month of the year the total precipitation for the year is 956.6 mm which is above the average of 832.9 mm.  This also means that we are already above the average for the year of 916.3 mm, and would only need an average December to end up above average for 2017.

Summary for November 2017:
Maximum Temperature 15.8°C
Minimum Temperature -12.3°C
Average Daily High Temperature 6.2°C (Long term average 6.3°C)
Average Daily Low Temperature -2.3°C (Long term average -1.4°C)
Total Precipitation 66.2 mm (Long term average 87.1 mm)

(Long term averages based on 1981-2010 data for the Waterloo-Wellington Airport)

Friday, November 3, 2017

October 2017 Summary

A very warm October with above average precipitation

Most of October was really warm and if it wasn’t for the cooler temperatures in the last week it might have been one for the record books.  As it was, the overall temperature was over 3.5 degrees above average making it the second warmest in almost 50 years (it was 5 degrees warmer than average in 2007).

We also saw 12 days in October where the temperature was over 20°C, we haven’t seen than many since October 1971.  But the most significant day was the 22nd when the temperature topped out at 25°C, this was tied with 1947 as the latest day of the year with a temperature above 25°C in the over 100 years of weather records in the region (just for the record it got up to 25.6°C that day in 1947).

As we have seen in each of the 20 years of weather data at the UW Weather Station, the first day that it went below zero occurred in October.  This year it first happened on the morning of October 26th, which is later than the recent average of the 13th.  The resulting length of the frost-free season was 170 days, a little longer than the recent average of 160 days.

The 77.0 mm of precipitation was just enough above the average of 67.4 mm to put the month in the above average range.  The total precipitation for the year is 890.4 mm is still well above the average of 750.6 mm.

Summary for October 2017:
Maximum Temperature 25.7°C
Minimum Temperature -1.2°C
Average Daily High Temperature 17.5°C (Long term average 13.5°C)
Average Daily Low Temperature 6.4°C (Long term average 2.9°C)
Total Precipitation 77.0 mm (Long term average 67.4 mm)

(Long term averages based on 1981-2010 data for the Waterloo Wellington Airport)

Sunday, October 1, 2017

September 2017 Summary

Some historical temperatures during a dry September 

Well that was quite an end to September with the longest heat wave of the “summer” and some historical temperatures.  The most significant streak was the 15 days above 25°C between the 12th and the 26th, that is something we have never seen before in September during the 100+ years of weather records in the region (the previous record was 13 such days back in 1947).

Some other notable events were the 5 days in a row above 30°C, which is something we have only seen a few times, the last was back in 1952.  Finally, the high temperature on the 24th of 32.2°C was the highest seen that late in the year since September 24, 1931 when it was 32.8°C.

Not surprisingly, the overall temperature was almost 3 degrees above average, what might be surprising is that this is colder than the last 2 years although they didn’t have the extreme highs we saw this year.  It is also useful to remember that this year the month started off cool during the first week.

But since I have you here can we talk a bit about recent Septembers?  Fun fact: no other month has seen more consistently above average temperatures.  In the past 20 years of data at the UW weather station, there has not been one in the below average range and only once was it even slightly below average (by 0.1 degrees in 2006).

The month was also very dry with only 38.0 mm of precipitation compared to the average of 87.8 mm, with half of the total coming during the first 4 days.  This dry month puts the total precipitation for the year at 813.4 mm, which is still well above, but a bit closer to the average of 683.5 mm than it was at the end of August.

Summary for September 2017:
Maximum Temperature 32.2°C
Minimum Temperature 3.8°C
Average Daily High Temperature 24.1°C (Long term average 20.4°C)
Average Daily Low Temperature 10.7°C (Long term average 8.6°C)
Total Precipitation 38.0 mm (Long term average 87.8 mm)

(Long term averages based on 1981-2010 data for the Waterloo Wellington Airport)

August 2017 Summary

An average August for both temperature and precipitation 

Although we didn’t see lots of really hot temperatures this month (only one day above 30°C), we also didn’t see lots of cold ones.  This resulted in the overall temperature being just 0.2 degrees below average, but this is still within the average range.

This may be surprising to some, but the fact is we have seen a string of warm months of August in recent years with this year’s overall temperature being the coolest since 2008.  In the 20 years of data at the UW Weather Station, only one August (2004) was cold enough to be in the below average range.  It was also a lot cooler than last year when we had 8 days over 30°C in August.

The month started out very wet, but with drier conditions in the last week the total precipitation of 93.6 mm was within the average range coming in a bit higher than the average for August of 83.9 mm.

The total precipitation for the year of 775.4 mm is well above the average of 596.0 mm.  For the last few months we have been in second in the “wettest year to date” category, however, there were lots of wet months of August in the past so we have dropped down to the sixth wettest year so far since records in the area began just over 100 years ago.

Summary for August 2017:
Maximum Temperature 30.7°C
Minimum Temperature 6.2°C
Average Daily High Temperature 24.5°C (Long term average 24.8°C)
Average Daily Low Temperature 12.9°C (Long term average 12.9°C)
Total Precipitation 93.6 mm (Long term average 83.9 mm)

(Long term averages based on 1981-2010 data for the Waterloo Wellington Airport)

Thursday, August 24, 2017

Solar eclipse 2017

These are my recollections of my trip down to the US to get on the line of totality during the solar eclipse on August 21, 2017.  As well as just experiencing the eclipse I also took along a temperature sensor to record the effects of the sun being blocked.

Just a bit on the logistics, I stayed in a small town called Glasgow, Kentucky the night before the eclipse and woke up early to drive to Bledsoe Creek State Park in Tennessee which is east of Nashville.  I was worried there might be some traffic, but it was open roads all the way.  I got there about an hour and half before the park opened and was car number 120 in line.  The park was mostly forested, but there was a hydro cut where most people set up their camps as there was a pretty good open view of the sky.

It was nice being somewhere that wasn't wall to wall people, but enough people to have a good group experience.  There were also a few people with very large telescopes, including one guy who had his connected to a computer screen so everyone could see a close up of the sun.

The day was really hot and sunny, with high temperatures of around 35C.  A few clouds appeared in the early afternoon, but just one covered the sun about an hour before totality, after that it was clear.

About 10 or 15 minutes before totality is when it started to get noticeably less bright, note I didn't say darker, but it started to feel not quite so hot and I could take off my sunglasses.  I think this was made all the more noticeable because it was so hot that day.

Once the moon's shadow actually passed over it of course became dark almost instantly, it wasn't pitch black but maybe about as dark as it is 15 minutes after a regular sunset.  Also interesting was the horizon which looked like sunset or sunrise, but instead of just in one part of the horizon it was all around.  Then everything went in reverse once the sun came back out.

Here is a video that I made just by putting a phone on the ground, it starts about a minute before totality and goes till about a minute after.  You can see how quickly it got dark and how the sky changed during the event (note the I'm standing out of the camera's view, I don't know the people who are actually seen in the video):

Something I didn't notice until I watched the videos was just how loud the cicadas got during the eclipse.  If you watch this "time-lapse" I made you can see both the reduction in the light as well as the background noise.  This one starts about 5 minutes before totality and each segment is about 1 minute apart:

Here is the graph of temperature during the eclipse in Tennessee, I kept one of the sensors in the sun (not the usual way to measure temperature I know) and one in the shade.  You can see that the sensor in the sun went down about 7C and the one in the shade got down to about the same temperature but started about a degree lower (the variation in temperature before 14:00 is probably just me setting everything up getting the sensor out of my car, as well the temperature looks like it was still going up when I left the park so I didn't get the entire rising limb of the temperature graph):

And closer to home, at the UW weather station there was understandably a lessor effect on the air temperature:


With the eclipse being 75% or so in the region, there was a large effect on the incoming solar radiation and the wind speed, as shown in the graphs below:

Overall it was a great experience and I recommend trying to get into the path of totality if you can make it.  The only downside was that after getting out of the park there was about 5 hours of bumper to bumper, stop and go traffic to get away from the totality line.  So my biggest advice for the eclipse in 2024 is that wherever you are, stay somewhere close and spend the night so you don't have to deal with the traffic.