October 2010 Weather Report

 In summary a warm and wet month, which is to be expected with La Nina being designated.  In fact, looking at increased rainfall as the key impact of La Nina (and disregarding a few trivia such as Normal Distributions) this month is 2 SD above mean and thus definitely in La Vieja - the Old Female,different to El Nino in both age and sex.

Rainfall

We totaled 130.6 mm for the month.  This is significantly above last year and the median.

There were non-trivial (ie >0.2 mm) amounts of rain on 14 days in the month.  (In another context a meteorologist noted that towards the end of the month Canberra had rain on 10 consecutive days: a record run.)  None of the falls were dramatically heavy - and most of the higher (deeper?) accumulations were very gentle, steady falls.

The pro-rata estimate for the year is at 1029 mm.

The actual fall to the end of October was 856 mm which is greater than 19 of the 41 annual totals for Mallacoota.  So definitely a soggy month/year.

Temperatures

My core measure of overall temperatures is the difference between the average daily temperature and the long term average.  Both come from the BoM site.  The overall result for October was +1.37C and largely due to above average minima: the re were below average maxima on 18/31 days.  The chart shows the progress of the anomaly through the month.

My second overall measure is to show the daily temperature extremes from my Weather Station.  It clearly shows the very hot days at the start of the month.

Minimum Temperatures

The average minimum temperature from my weather station (12.27C almost identical to the 12.2C recorded by BoM)  was well above both October 2019 and the long term average for the month.  In part this appears to be due to the continual presence of clouds, not allowing overnight cooling.

This average is the second highest recorded, being topped only by 2015.

Maximum Temperatures

The average maximum at my Weather Station (21.13C vs 19.7 from the BoM) was well above the past.  

In part this reflects the frequent impact of a cooling sea breeze on the BoM site.  Looking at the maximum component of the calculation to arrive at the anomaly shows that the BoM recorded 18 days in which the maximum temperature was lower than the average for that day of the month.  However due mainly to the two very warm days of 3 and 4 October even the BoM average for the month was .5 above the long term value.

The BoM maximum, on 3 October, of 33.8C was the 5th highest maximum recorded for a day in October.

Humidity

The daily pattern for the 2 standard rimes is rather strange with the series showing very similar values.  Again I relate this to the considerable cloudiness of the month.

The value I am using as the long term average is some historic BoM data so is really only useful to give an annual pattern.  I am surprised that my readings appear to be consistently higher than the BoM series: looking at the values for October values for both standard times have correlation coefficients of ~0.94 and the average value over the month is close (especially for the 1500 series) .

The 0900 series is very close to 2019+ but above average. 

In contrast the 1500 series is well up on 2019 and average.  Cloudiness again?

Wind

There were some quite strongly windy days with runs of more than 200km ...

 

... but overall it was less windy than 2019 and the adjusted BoM average.

The final aspect of the wind is the direction it comes from.  In the past I have done this through a pie chart, as I like the idea of a circle matching the compass.  However it is messy as the slices of the pie vary in width with the number of cases.  (I realise that what I want is a chart in which the slices are of equal width, but the length of the bar indicates the number of cases.  I cant find such a chart in Excel's offerings.)  As a change I have compiled a column chart showing the number of observations of the the direction of the wind at the hourly reading times and the direction of each strongest gust.

I shall ponder this form of presentation a little more.