Saturday, 4 March 2017

Happiness is wetness

Carwoola has had a very dry start to the year.  So it was very pleasing to score 9.8mm of rain on the 2nd of March.  This was enough to get the Creek running.
 From looking out over the Plain on the 3 rd
 I had hopes that we get a good follow-up.  But only amounted to 2mm.

The BoM forecast for the weekend of 4-5 March has been up and down over the last few days and had ended up in the low end of their estimates.  Early on the 4th I consulted the radar ...
... (and, using the most reliable forecasting technique, looked out the window) which led me to conclude we could get a fair drop.  So it was, throughout our dog walk.  On returning home, with about 6mm in the gauge the radar looked like this - we're at the red x and the system seemed to be heading NNW.
By 10 am we'd got to 9.8mm (again) with a month to date of 21.9mm.  So where does this fit into past records?  Here is a plot of the March records for Carwoola (at various locations in the general area) since 1985.
The mean value for 1985 to 2016 is 50.66mm.  Clearly 1989 and 2012 are outliers and excluding them gives a slightly more normal mean of 38.7mm.  The median value (half years above and half years below) is 42.4mm, so a fair expectation is about 40mm in a normal March.

Another way of thinking about this is to look at the number of years in which the rainfall was in a few classes.  I hope this chart is comprehensible: it show that the commonest class is 10 - 39.9mm  with 40 - 59.9mm not far behind.  Again about 40mm would be a fair expectation.
The rain on 2nd of March didn't seem to sink in very much, but that of the 4th may have started to get down to where some shallow roots at least can get hold of it.  Hopefully it will also have started wash the smell of smoke and charcoal out of the air!

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