Monday, 1 December 2014

Summer is a'comin' in: November weather Report

Using my definition of Summer as months with maxmum temperatures over 30oC it has already come in!


The first graph is the usual depiction of the range of temperatures.
 There were 4 maxima greater than 30 and only 2 minima less than +2.  We often feel that what makes heat bearable is if it cools down - even relatively - at night.  So the 10 days with a range greater than 20 degrees are very good.

When glancing at the graph I noticed that the minima seemed be mainly close to or above 10oC, and wondered how this compared with other months.  The graph below is the inverse of this, showing the percentage of days with a minimum below 10oC
This confirms that we aren't in Winter anymore.


As we scored 48.4mm in a few good falls the month wasn't too bad.  As shown by the chart we were well below last year's fall, and even more behind the 7 year average.  We were away for one of the downpours, but it seemed to scour things out a little in the drive so I suspect it was rather heavy,  The radar image during the storm - seen on the 'net from Orange - supports that proposition.  So does an analysis of the rainfall rates displayed by my weather station for 16 November.
To make the green lines representing amounts easier to see I have multiplied them by 10.  This clearly shows that the storm finished with a metaphorical bang (and probably a physical one).  For the period ending 0930 we received 12mm at a rate of 120mm per hour!  No wonder run off was a tad rugged!

We had another storm late in the evening of 24 November, shown below with the same adjustments etc as above.: 
This was much less rain, but with a peak rate of 140mm per hour, delivering 8 mm.  We didn't get as much run off but it was very noisy when I was trying to sleep.


Looking at my customary relative humidity reading for 1700 hrs was not particularly exciting since it showed a higher reading on days when it rained and that was about it!  However I now have a year's worth of data (including about half of November 2013) so thought it would be interesting to look at the monthly averages.
A very nice little parabola, for any graph-men amongst the readership.

I then wondered how the variation through the day compared between November and the moistest month of June.
Both show a dip across the daylight hours but June is always higher and the dip is far more pronounced in November.


The next chart shows the maximum gusts in a day.
This shows the gusts associated with the storm of the 16th.  I think we experienced them in Orange at about the same time!  A couple of other 'high gust' days  on the first and the 14th were also associated with storms in the area, although they didn't dump on us.

There are two bits of accepted wisdom about wind in this area:
  • the prevailing wind is from the w - NW segment of the compass; and
  • the equinoxial months are the windiest.
My gut feeling from looking at a year's worth of data is that data from my weather station doesn't support either of those statements.  When I am next short of a topic for a blog post I shall have a go at some analysis to see what is going on.

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