Overall grotty episode

There seems to be a decent break in the rain and wind ( I have even, briefly, seen a strange yellow object in the sky this morning - giving a nod to the Billy Cotton Band Show, BBC circa 1965).  Thus I calling this event done and dusted.  Total rainfall at my WS for the 6 days was 125.6 mm.

The total rainfall by hour is shown in the following chart.  I hope the axes in this, and some other charts can be understood as it involves some ad-hoc text boxes overlaid on the axis values by EXCEL.

While the 25th-26th was the most miserable with constant light rain for 2 days the peak rain episode was overnight 27th to 28th.  This was explained by a friend (a retired meteorologist) in a weather forum:

"This is a cold occlusion with three airmasses involved: the coldest air is moving in from the SE undercutting warmer cold air, which is the residual airmass over NE Bass Strait and the far South Coast, both of which undercut the subtropical moist air that brought our heavy rain earlier in the week. The subtropical airmass is still hanging around, but is now entirely above the surface. Heavy rain, storms and even funnel clouds can develop at the point above the surface where the warm air wedge is at its lowest, known as the trowal, short for TROugh of Warm air ALoft.

The trowal came closest to shore in the middle of last night near the VIC/NSW border, giving Gabo Island 41mm between 21:00 and 03:00 for a 24 hour total of 75.4mm and Mallacoota 40mm from 21:00 and 03:00 to give 60.0mm to 09:00. There's a straightforward description with diagrams of the different types of occlusion and associated weather in Wikipedia, and I find the diagrams are essential to getting my head around the mechanism.

My weather station also records peak rain rate in each hour.  The next chart shows the rate with the total amounts also shown in the background.

It was basically mild (in terms of minimum temperatures) to cool (in terms of maximum temperatures.  The drop in temperature on 23 August is quite evident but during the rest of the event a blanket of cloud kept temperatures quite steady.

For most of the event it was quite windy.

Rather unusually the wind was worse to North of Mallacoota than to the South.  The strength of winds to the north is shown in Australian Weather News by it setting a gust record for the month at Montague Island and all time gust record at Point Perpendicular. 

In another post I tried to bring the three unpleasantnesses (wet, cold and windy) together by counting the number of hours per day where the temperature was <10C; and the wind above 20kph; and >1 mm  of rain in an hour.  The 25 August set a new record with 9 hours meeting those criteria of crappiness.  A further 2 faecal hours were recorded on the 27th and i more on the 28th.  A scatterplot shows the incidence of these 'orrible days since I began recording in February 2019.