I give up on this weather!

In my now distant days in the workforce a colleague once said "I am rarely right, but by God I was wrong that time!"  A friend was talking about experiences as a management consultant and particularly an event at which he asked a group of executives to describe their worst cock-up.  Eventually it was the CEOs turn and he sat silently.  My friend asked him "Do you not have any mistakes."  The answer was "Oh no.  I'm just embarrassed for choice."

I recalled those comments after 

1. saying that the event of 2-3 June was not an East Coast Low (ECL) because it didn't come down the East Coast and
2. then looking at a BoM map site showing the national pressure maps for the previous 6 days. 

Here are a sample of the maps:

Converting this to Eastern Australian Time means adding 10 hours so this is 2200hrs on 1 June.

The next image is for 2200hrs on 2 June.

The 3rd image is for 1000hrs on 3 June.

Obviously the system did come down the coast, albeit a bit further offshore than usual.  So reflecting back on the reasons why I thought, at various times, this wasn't an East Coast Low:

1. During the event the Bairnsdale weather radar didn't show a mass of rain happening to our North and moving South.  Rather it showed rain to the West sending showers  - some intense - our way;
2. The winds seemed  to be coming from the South or West rather than the East; and, checking more recently more recently 
3. The weather stations to our North  (Green Cape, Moruya Airport; Ulladulla; and Nowra) didn't record a great amount of rain.

All of these can be explained by the low pressure system being a little further off the coast than is sometimes the case.  Thus the winds in our area were probably those from the anticlockwise circulation around the high pressure system, until the low was almost past us when the clockwise circulation arrived  with Southerly winds.

Whatever: I got it well wrong.  To quote Benny Hill "Learning all the time!"

Moving along to the situation on 6 -7 June.  Let us begin with two more pressure charts, from the "Interactive Weather and Wave Forecast Maps" series, for times of 6 June.  The first 1 is for 0400hrs on 6 June (ignore the reference to validity).

The second is for 0700 on 6 June

Matching these forecasts is a BoM heavy rainfall warning for the area in blue.

I was woken by the sound of heavy rain over-running the gutters at 0400hrs.  When I gave up trying to get back to sleep (about 0430) I was astonished to see my Weather Station (WS) showing a fall of 17mm.  Both the BoM sites showed modest falls so I checked the radar and it was almost clear (I didn't take a snip but this from 0644 AET gives a similar picture).

Having quoted England's greatest philosopher (Benny Hill) may I now cite Barcelona's contribution to scientific process (Manuel, from Fawlty Towers) "Que?".  

By 0600hrs my WS was showing 22mm (after 0.8mm on the evening of the 5th).  I have just checked my Nylex plastic gauge - which I emptied on the 5th - and it read 23mm.  So my WS is doing the right thing.  The chart below shows the situation to 0600hrs AET from the 3 sites already mentioned, and the Wundergound site in Clarke St.

Obviously a very nasty squall (or two) came over our house between 0300 and 0400.  The records from Clarke tend to back this up.  I have since found another Wunderground site in Shady Gully that is showing 18.3mm at 0750 which is pretty consistent with Clarke St (16.3mm at 0750) and my WS (23.2mm at 0750).  

As a means of assessing the squality of the falls the next chart show the amount of rain and the maximum rate for each hour as recorded on my WS.

The three periods with higher rates are all above 25mm/hr.  The database of WS records from February 2019 to end May 2024 has 46,179 records of which 2,640 (5.7%) have rainfall recorded.  Of the records with rainfall 344 (13.0%) have an associated rate > 25 mm/hr: so the three heavy falls are towards the upper end of rates, but not dramatically so (the 25 heaviest falls are all >100mm/hr).