Friday, 19 May 2017

A note about May rainfall

A note was posted on the Carwoola Community Facebook page about the impending deluge in the area.  At the time of writing (13:40 on 19 May) it hasn't yet made it, but there have been a few sprinkles.  As we have only had 2.2mm so far this month some more rain would be welcome (unless you're trying to do a concrete pour).

This has led me to have a look at what has gone on in past Mays.  We have records for various properties covering the period from 1984.  The minimum fall recorded for the month was 1mm even in 2005.  Since we have lived here the lowest May total has been 3mm in 2009.

Here is a distribution of the falls by size, counting the number of years in each class.
It is a bit difficult at this time to work out what BoM are forecasting with precision, but their rainfall forecast maps are suggesting 15-25mm on Friday and Saturday.  If both days are at the low end of the scale we would end up getting at least 32mm for the month (in the middle class) while the upper range giving a total of 52mm puts us up a class.

I, and I suspect many others, have accessed the Elders 28 day forecast for an idea of what is to come. It has generally been quite reasonable (accepting that one BoM forecaster has been reported as saying anyone who goes more than 6 days out is dreaming!)  However the site has recently been looking like this:
The next week is entirely consistent with the BoM forecast but the remaining 3 weeks are blank.  That has been the consistent appearance of the site for the last 2 weeks.  It looks almost as though they have given up trying to forecast for the final 21 days of the 28 day cycle.  I will despatch an email to find out what is going on.

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