May 2023 Weather report

 The promised El Nino has not yet appeared with above median rainfall.  Temperatures over the month as a whole were below mean but there was a very warm patch to finish the month.

Rainfall

We recorded 77.2 mm for the month as a whole.  This is 12.9% above the median fall, and takes the year-to-date total to 382 mm (7.2% above the median year to date).

The daily falls show that nearly all the wet came in the early part of the month.  Most of the rain came in steady falls: no extreme rates to report.

Temperatures

Overall it was a cold month with the anomaly ending at -1.08C.

The chart of temperature extremes shows that the main reason for the outcome was (very) low maxima.

Minimum Temperatures

The average minimum was a little below both the 2022 value and the longer term mean.

The lowest daily minimum was 5.6C, significantly below the long term mean minimum.  It coincided with a maximum also significantly below the average for that variable making that the only Cold Day of the month.  There was one other significantly low minimum, and 2 occurrences of minima significantly above the long term mean.

Maximum temperatures.

The average maximum temperature of 16.45C was well below the previous lowest average maximum (adjusted to make the Historic BoM data more consistent with my Weather Station) of 16.9C.  Looking at the BoM data without adjustment the value for May 2023 was 16.6 C compared with a long term lowest value of 16.1C in 2006).  Either way it was a very low month for maxima.

My WS recorded 2 days with significantly high maxima (shown clearly in the chart under the main heading) but 12 days with a significantly low maximum.

Humidity

The chart for the two standard-time humidities shows a very confused situation with a relatively high proportion of days in which the afternoon reading is higher than the morning value.  I expect this to be a timing effect reflecting when the wind switched to the South or SW.

Looking at history the 9AM reading is well below average while the 3PM reading is well above average.

Wind

The average daily wind run was 91 km.  This is a little below average, with many days less than 100km and only 3 above 15 km.

Tempest data

A friend who lives near the wharf has a weather station connected to the Tempest network.  This provides some additional data items to those available from my Davis.  Two variables I find particularly interesting are covered below.  I need a longer time sereies to attempt any insights from these data.

Lightning strikes

According to material I read on the Weatherflow website these relate to an area 40km radius around the station (while this seems hard to fathom, I note that my looking at Flight Radar shows aircraft visible to my eyesight that are 200+ km away).    There were 52 strikes in May 2023.  The chart shows a time series since this weather station commenced.

Solar radiation

The station also measures solar radiation: a topic of great interest in view of the use of solar radiation to power water heaters and electricity.