March 2021 rainfall event

 

Between 14 March and 24 March 2021 was a period of rain and showers with some thunderstorms, as a result of an succession of favourable synoptic features. During this period a total of 263.3 mm was observed and was the wettest period since 364.9 mm was observed between the 3 February and 14 February 2020.

In the past 30 years the rainfall event total was the 14th highest on record and was in top 7 % of rain event totals. For March the rain event total was the second highest on record and the highest since the current record high of 278.2 mm between the 28 March and 31 March 2017 associated with Ex-Tropical Cyclone Debbie.

During this rainfall event a large portion of the rainfall occurred during the last few days of the event where 203.3 mm was measured between the 22 and 24 March. The highest 24 hour rainfall total was 129.7 mm on 22 March 2021 and for March this was the third highest 24 hour rainfall total observed on record and which was the highest since the current record high of 153.5 mm on 6 March 2004 (squally heavy rainfall between the 5 and 6 March 2004). When compared to all previous months the highest 24 hour rainfall total was the 21st highest on record and the highest since 143.4 mm on 24 February 2018 (showers becoming heavy rainfall on the 23 and 24 February).

At the time of writing the month-to-date total is 297 mm, which is 177.4 mm above the long term median and 248.3 % of the long term median. For March so far this is the highest March total rainfall since 375.4 mm in 2017, which is the current record high. However considering that showers are expected during the rest of the month the final total may end up as the second highest on record, due to the current second highest being 301.25 mm in 1992. For all months this is the highest since 389.2 mm in February 2020.

Year to date rainfall is currently 519 mm, which is 88 mm above the long term January to March total (16.9 % above average). This is lower than the January to March rainfall total in 2020, which saw both well above average rainfall in January and February in contrast to near average rainfall in 2021 until the above average rainfall in March 2021.

The number of rain days have been 51 so far this year (of least 0.2 mm of rainfall excluding daily rainfall totals that are entirely from dew, mist or fog). This is 16 days above the long term average, is the highest on record as compared with previous January to March totals since 52 days in 2015 and the third highest on record. For March this is the highest number of rain days since 18 days in March 2019.

Note that rainfall totals are based on manually recorded daily rainfall totals measured as the 24 hours to 9am. This data is currently not displayed on this website, except as contained in the weather reviews. Therefore there will be differences to the rainfall totals shown on the website that are collected automatically from a different rain gauge and is measured as the 24 hours from midnight.

Some charts from this period are below where daily data is for the 24 hours from midnight. This is based on the existing graphs on this website, but uses a script that allows to show data between a specific date range, rather than using data in the last x days. This alternate format is not available on the website at this time which could be included in a future update.

 

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New air quality statistics

The air quality data we recently began to measure has been expanded to include statistics for this month, this year and all-time.  This data is now available on the this month and year and all-time record pages.

In the short period that we have been measuring air quality the air is exceptionally clean. For the vast majority of the time the particulates and air quality index values have been extremely low (good) and have been elevated to a slight degree only for fairly short periods of time.

To include these new statistics changes were required to be made to our database. Since the recording of air quality began from 26 December 2020, a routine is ran at the start of each day to fetch the data from the previous day to insert a new row into a database table for that day. However generally only the averages and maximums were shown, without the earliest time of the occurrence. With these improvements now the averages, minimum and maximums are measured for each day along with the time of minimums and maximums.

However, it should noted that these additions began from 7 February 2021, because we only retain the real-time data for 7 days (for data storage reasons). Therefore the time of occurrence will not be shown for statistics before this date. Also we collecting a vast range of daily parameters, most of which haven’t been published to a great deal on the web site, but is being collected for completeness and for future analysis.

To provide a bit more information about how this works a MySQL database procedure (as shown below) is scheduled to run at the start of each day to insert the previous day data into a table of daily air quality averages and extremes. This uses the ROW_NUMBER window function to calculate the earliest time for each individual minimum and maximum for each day. A query for each of one of these calculations are then joined to a query that essentially merges these calculations into one table. Because these calculations are rather expensive a variable retrieves the latest date of data already inserted into the data to limit the quantity of data that is calculated to only the data not already captured in the daily table.

These queries are both performed on the real-time table (every 10 seconds) and an 5 minute interval logged data table, with the results inserted into temporary tables. These two temporary tables are then used to determine the greatest value of each of these data sources to insert the data for each column of data. This is so that the data is suitably captured due any possible network outages that may affect the currency of data. The SQL COALESCE function is used to return the first non- null value from these data sources, with preference provided to the Real-time table.

A PHP script contains SQL queries that retrieve the necessary information from this table and are assigns to variables when the web page is visited. This allows for these statistics to be shown on the web page and is the same principle as several other statistics on these and other pages. The SQL queries are fairly simple because the daily air quality data already shows all the required summarised information for each day.

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December 2020 weather review

The review of the weather at Ferny Grove during December 2020 is now available.

in December 2020 overnight temperatures were over 1 ºC above average and was the highest for December in 11 years. Daytime temperatures were close to average and the lowest in 5 years. Minimum temperatures in December were predominately above average during the month and were near or below average in the middle of the month and at the end of the month. Maximum temperatures in December saw two periods of warm days at the start of the month and between the 18th and 23rd, as well as near average or below average temperatures. The first 8 days of the month saw warm days and nights that were up 7 ºC above average during a low to severe intensity heatwave .

Rainfall in December was above average with a total of 145.9 mm (112.9% of the long term average). This is the highest for December since the current record high of 450.1 mm in 2010. The annual rainfall total remained above average at 23.3% above the long term average and was the highest since 1263.6 mm in 2015. Most rainfall in the month occurred between the 7th and 18th during an active period of drizzle, showers, rain, and mild thunderstorms. The first 8 days of the month was dry and later in the month there were some drizzle and light showers on some days. The highest daily total rainfall on the 14th of 70.1 mm was the highest for December since 82 mm on 28 December 1999. This rainfall was a result of light to moderate rain from the evening of the 13th to early on the 14th that was associated with a coastal low pressure system that brought severe weather conditions to coastal areas of south-east Queensland.

Most long period rainfall totals continue to remain below or well below average, that improved for many of these periods. 6 monthly rainfall improved a little to 18.3 mm below average, while 9 monthly rainfall deteriorated from 171.9 mm above average to 52.7 mm below average. 12 month rainfall improved by 91 mm to 94.2 mm above average and 18 month rainfall improved by 100 mm at 38 mm below average. 24 month to 48 month rainfall was between 156.7 mm below average for 48 month rainfall and 366.1 mm below average for 24 month rainfall. Compared with the same period in the previous year these periods improved, and the greatest improvement was 12 monthly rainfall that improved by 564 mm.

The summary containing the key information can be found here.

The full report of more detailed analysis is available here.

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November 2020 weather review

The review of the weather at Ferny Grove during November 2020 is now available.

in November 2020 overnight and daytime temperatures were close to average. Minimum temperatures were near average or below average in the first half of the month and then warm nights during the rest of the month with some cool nights. Daytime temperatures were mostly below average in the first half of the month before most days were warm during the rest of the month. An 8 day cool period occurred for the daily maximum temperatures between the 6th and 13th that peaked at 7 ºC below average.

Rainfall in November was well below average with a total of 4.7 mm (4.9% of the long term average). This is a new record low for this location for the past thirty years beating the previous record low of 14.2 mm in 2019. The year to date rainfall remained above average at 3.8% above the long term average. Most rainfall in the month occurred on the 17th from the edge of two mild thunderstorms when 4 mm was measured. On the 5th there was a mid-afternoon brief light shower from a thunderstorm passing to the south with 0.5 mm of rainfall. On the 13th there was some light rain but with no measurable rainfall.

Most long period rainfall totals continue to remain well below average, that improved for some of these periods. 6 monthly rainfall improved slightly to 58 mm below average, while 9 monthly rainfall reduced significantly from 97.2 mm in the previous month to 205.9 mm below average. 12 month rainfall remained nearly the same as the previous month at 3.4 mm above average. 18 month to 48-month rainfall was between 140.7 mm below average for 48 month rainfall and 384 mm below average for 24 month rainfall. Compared with the same period in the previous year most of these periods improved, except for 36 monthly rainfall which have worsened and was the lowest since 2008 when it was 334.2 mm below average.

The summary containing the key information can be found here.

The full report of more detailed analysis is available here.

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October 2020 weather review

The review of the weather at Ferny Grove during October 2020 is now available.

During October 2020 overnight temperatures were close to average and daytime temperatures were above average. Overnight temperatures were near or below average in the first half of the month before warm nights during most of the second half of the month. The 22nd to 29th saw warm nights of up to 6 ºC above average. Daytime temperatures were above average throughout the month with some days that were cool.

Rainfall in October was above average with a total of 119.5 mm (185.4% of the long term average). The year to date rainfall remained above average at 11.5 % above the long term average. From the 19th was an active period of showers, rain and thunderstorms with some moderate to heavy falls. 14 mm of rainfall fell in 8 minutes on the 25th during a severe thunderstorm with marble size hail. On the 31st was 2 hours of thunder from 4 nearby thunderstorms with very little rainfall.

Long period rainfall totals remained well below average during most periods though improved for some periods. 6 monthly rainfall improved by 130 mm to 64.5 mm below average. 9 monthly rainfall remained above average at 97.2 mm above average while 12 month rainfall was 12.2 mm above average, improving from 58.6 mm below average in the previous month. Periods between 18 to 48-month remained below average and was as much as 624.9 mm below average for 36 month rainfall.

The summary containing the key information can be found here.

The full report of more detailed analysis is available here.

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Solar and air quality data

New data is now available on multiple pages to incorporate solar radiation, sunshine and air quality following the start of recording these parameters from 26 December 2020. These sensor were installed along with the change to using a Weatherlink Live receiving unit between 19 and 22 December 2020, which were then tested for compatibility with our processes and existing data.

The following pages have been updated with additional data:

  • The home page: the solar and air quality data have been added to the real time updates on the home page, sunshine/ night-time bands have been added to the real-time graph, the station forecast have been removed and a Bureau of Meteorology forecast added
  •  Gauges: A gauge for solar radiation was added
  •  Today and Yesterday: Averages, Totals and Extremes for Solar, Insolation, Sunshine and Air Quality added
  •  System Status: Reworked to align with the system changes and to provide additional system information now available with this change
  •  Glossary: Updated with additional terms of Air Quality, Insolation, Solar Radiation and Sunshine.

 A routine now runs at the start of each day to collate the air quality data into an additional daily database table used in the Historical graphs. The Realtime database table was altered to include air quality data. A monthly air quality database is also populated with data each 5 minutes.

A combination of our regular data updating on the website and these Realtime and Monthly database tables are used to update the tables and graphs on the website. The Realtime and Monthly database tables are also used as in the input to update the daily air quality database table.

Coming soon will be the addition of UV data. Also air quality data for the this month, this year and all-time records is also planned. Additional data will need to added to the daily database table in order to show that data along with the date and time of the occurrences.

Under progress is the calculation of daily potential evapotranspiration and possibly evaporation now that we are measuring solar radiation. Due to limitations with the system I am using it appears these will have to be calculated, rather than supplied by the weather station directly. These are rather complex multi-step calculations, so considerations are being made with the practicalities of that and what data will be shown from that on the website.

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September 2020 weather review

The review of the weather at Ferny Grove during September 2020 is now available.

During September 2020 overnight temperatures were above average and were the highest in 10 years. Similarly to August 2020, the month saw very few cool nights and many warm nights throughout the month. The 18th to 25th saw overnight temperatures peak at 9 ºC above average. Daytime temperatures were close to average and saw a mixture of above and below average temperatures.

Rainfall in September was below average but was close to the long term median, with a total of 14.2 mm (42.7% of the long term average). The long term rainfall for September is generally quite low, hence the close to median rainfall. While the rainfall total was quite low and continuation of the trend of low monthly rainfall totals, the year to date rainfall however remains above average at 9.8 % above the long term average and the highest since 2015. Low daily rainfall totals with light showers during some days during the month. A thunderstorm passed to the south on the 25th, as well as another thunderstorm to the north and brought a brief light shower.

Long period rainfall totals remained well below average during most periods while deteriorating further. 6 monthly rainfall fell significantly to 161.7 mm below average being more than 6 months since significant rainfall at the start of the year. 9 monthly rainfall was 79.4 mm above average while 12 to 48-month rainfall was between 72.4 mm below average for 12 month rainfall and 245.3 mm below average for 24 month rainfall.

The summary containing the key information can be found here.

The full report of more detailed analysis is available here.

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Website analytics

A new page is now available that has been in development lately of a different nature to the existing content on the website. We use the privacy friendly open source website analytics platform Matomo that is hosted on-premises where we fully own the data that allows us to understand the usage and interest in this service we provide.

This website analytics data have been used to determine whether there is a correlation between the visits are made to the website compared to amount of the rainfall at the time and to test whether visitor activity is stronger during wetter weather. From this it have been discovered that at this time that while a lot of visits are made when there is no rainfall, when expressed in percentage terms that there is a general trend in more interest in the website during wetter weather, whilst visits across the range of rainfall totals are very consistent.

This information of visits by rainfall have been published on the new page as four charts using this information calculated from our databases. In addition to this, more standard summarised data over time of the number of visits, the type of devices used and the visits made by returning and frequently returning visitors. On that page are explanations of the definitions relating to this data and also there are key metric for various periods to provide a quick summary.

Thank you to all those who have shown an interest in this website and the many who have come back to this website many times. I have been quite surprised at the strong visitor activity that has occurred and there is clearly an interest on local real-time weather data. This website is in continued development with completed new works announced on this blog in addition to updates to the website that are mentioned on our Website Info page.

The below information is provided to share how this page is put together at this time for anyone who want to have more understanding of this. Both the analytics data and weather data are stored in MySQL databases, which are both used to create four database tables containing the data for the four graphs for the visits by rainfall. These calculations use table joins and appropriate aggregations to produce the data to allow for a fair comparison. But because these are quite complex calculations the database queries are not executed when a graph is viewed as retrieving the current data will add significant time to load the graph.

So given that this data doesn’t change too quickly, a SQL procedure is executed once a month to update the data for when someone visits the page. The SQL code used in that procedure is similar to the below example. The methodology used is that a table is created to calculate the amount of rainfall in the previous 24 hours for each hour during the past year, of which this data is not readily available in the database. This is derived by first calculating the rain for each hour, then the cumulative rainfall during the last year for each hour and then calculate the amount of rainfall for each hour compared to the same time in the previous day.

Once we have that data then table joins are used to merge the analytics data to this rainfall data for each of the four tables. Finally at the end the rainfall data is deleted, as the data is no longer needed.