November 2023 Weather Report

 In terms of temperature the month averaged to being warm, but this was largely due to high daily minima (usually overnight temperatures holding up).  The outstanding feature of the month was the dramatic rainfall caused by an East Coast Low in the last two days of the month, making it the second wettest November on record.

Rainfall

In essence a month of two halves.  From the 1st to the 19th my Weather Station (WS) recorded rainfall on 2 days, totalling a miserable 2.2 mm.  From the 20th onwards the WS recorded rain on 10 of the 11 days, falls above 5mm on 5 days.

As expected this total is way above last year and the median fall for November.

A time series for Novembers shows the result to be outstanding (but not unprecedented)!  The values for 1981 and 1982 come from Gabo as BoM has no data for those months.  (The highest rainfall for any month shown by BoM for the Airport site is 440mm in April 1989.)

Apart from the sheer amount of rain in the last 2 days of the month the contrast between the steady, modest-rate falls until 1400hrs on the 30th and the series of squalls which followed was dramatic.  

In terms of outcome, the closure of the Genoa Rd by a landslide has had the greatest impact.  There has been a fair amount of flooding around the area due to the rising level of the Lake.  This seems to have been a 'perfect storm' combination of heavy rain, high tides and an onshore wind.  A couple of photos:

Lakeside Drive at 0800 hrs on 1 December.

Where have the Goodwin Sands gone?

Temperatures

My usual measure of the overall temperature is the difference between the average temperature for a current period and the long term mean of that measure: this is the anomaly.  For November looking at the average temperature the overall value is +0.95C.  After a very cool start to the month followed by a warm spell (see below) the anomaly mainly resolved to close to +1C.

Most of the extreme temperatures were moderate: they are discussed in the following sections.

Minimum temperatures

The average minimum temperature for the month was 13.77C well above the long term mean of 12.27C, as shown in the following chart.

An overall time series of minimum temperatures is not of great assistance as it varies greatly from year to year.  Instead I have compiled a set of annual series for readers to contemplate.

I have also examined the daily values for significant variation from the long term mean.  In November there were 9 days in which the minimum was more than 1 standard deviation above the long term mean (but no occurrences of minima more than 1 SD below the mean).  Indeed there were only 6 daily minima below the average for that day.

Maximum Temperatures

The average minimum temperature for the month was 22.53C slightly above the long term mean of 22.12C, as shown in the following chart.

The set of recent average monthly maxima are interesting in that they show the maxima for the colder months to be above average, but for the last two months have moderated, probably due to cloud cover.

6 daily maxima were >1SD above the long term monthly mean and one day (11th, maximum 34.3C) was >2SD above.  only one of the significantly high maxima coincided with a significantly high minimum, meeting my definition of a Hot Day.  Due to lack of consecutive Hot Days there was not a Heat Wave but I considered 7th - 11th and 21st to 26th as Warm Spells with maxima and minima above the average and several values for one of the indicators significantly so.

Humidity

Overall a somewhat sticky month, with both 0900hrs and 1500hrs relative humidities well above the average for those standard times.  From the 22nd onwards relative humidity was always above 70% for both those times.

Wind

Normally November is one of the windiest months but the last month was, overall, relatively still as far as my WS measured it.  My WS has poor exposure to wind, especially from the South and East, and  unfortunately the BoM publishes (at no charge) very little information about wind.  Comparing the maximum daily Gusts from the two sources shows they correlate "fairly well"  (correlation coefficient of 0.52).  

There were a couple of windy days early-mid month, and again in the East Coast Low period, as shown in this chart of daily runs from my WS.