March 2023 Weather Report

A fairly dry, warmish month.  i have put the qualifier on dry as wile rainfall was not great, humidity was about the average.

Rain 

The total fall at my Weather Station was 60.6mm, 89% of the median fall.  However 32.6mm (53.8% of the total fell on the 1st of the month.

A comparison with previous readings shows both the lower value for 2023 and the outstanding falls for March (and April) in 2022.

March rainfall is very variable over time!  I have tried hard to fit a trend line to this but have been unable to pick a significant one.

Looking forward, my pro-rata estimate for 2023 as a whole is looking rather low!  The current estimate is 787mm which is below median.  I think La Nina has gone for a comfort stop.

Temperatures

The anomaly for March ended at +0.63C.  Looking at the development of the anomaly through the month shows a variable first half with a steadily increasing value after the 13th.

I have also compiled a time series of monthly anomalies.  I haven't (yet) tried to get my head around this, but my memory is that the just-completed set of La Nina events began in Spring 2020, which may explain the high values then and the reasonably stable (OK, it fluctuates wildly month to month, but within a fairly narrow range) set of values since. Please excuse the unusual values on the x-axis but it gets year and month into a single value.

The chart for daily extreme temperatures appears unremarkable except for the 'steady' daily range (ie difference between maximum and minimum.  I have not analysed this in detail (yet) but it appears to be limited to a very tight band.  A future post will look at this.

I will do more detail on this later, but the report is delayed already.

Minimum temperatures

The minima were a little cooler that 2022 but warmer than the average.  This also shown in the day by day comparisons underlying the anomaly: nearly every day in the second half of the month had a higher than " average for date"  minimum and overall there were 7 more than expected days with a high minimum.

There were few days with a minimum significantly below average and no days with both minimum and maximum below average.

Maximum Temperatures

I recorded 5 maximum temperatures > 1 SD above the mean maximum for past Marchs.  3 of those coincided with days on which the minimum was also significantly above the monthly mean minimum which I define as being a Hot Day.  However the three Hot Days were not consecutive so we didn't record a Heat Wave.

Humidity

On eyeballing the first graph of daily values for the 2 BoM standard times, it seemed that the afternoon values were surprisingly close to those in the morning.  Certainly the pattern of the 2 readings is very consistent.

Looking at morning values alone shows them to be rather higher, compared to the mean, than might be expected with the relatively low rainfall.

The afternoon readings are about on average.

Wind

Overall the average daily run was well down for the month.  However there was a long run on the 6th (28th longest all time of 1479 records; 3 longest of 155 March records).  As an incidental observation this emphasised the fact that long runs occur in Spring rather than Autumn. 

Tempest data

Most of the data above comes from my WS (with some of the historical material being based on BoM data from the airport site).  A member of the community has a site near the wharf which reports to Weather Underground and Tempest.   

The Tempest material is interesting on a couple of grounds:

1. It provides details for an additional area in Mallacoota; and
2. It covers a range of additional variables to those collected by my WS (or the BoM site).

I will do some analysis of the common items (temperatures, rainfall) in a separate post to investigate how the site compares with others in Mallacoota.  

The following sections look at some of the additional variables about Mallacoota weather.  Thus far I have only extracted data for 7 months so not a great amount of commentary can be offered.

Lightning strikes x month

This simply the number of lightning strikes recorded per month.  This is recorded by the Weather Flow Weather Station which counts the strikes over a 40km radius.

Using  Google Earth to plot a circle of 40km radius around Mallacoota delivers the following result:

Solar Radiation

The station also measures solar radiation, measured in Watts/Metre squared.  Two values are delivered each day the maximum and the average.  The first chart below shows both of those measures  

To gain a little initial insight into the distribution of these values I have compiled a chart for the first 6 days of April 2023.  It shows a moderate/low level of correlation (r= 0.42) between the two series which is consistent with eyeballing the chart.