Monday, 5 August 2013

Weather Report for July 2013

Although I was away for the last 2 weeks of the month my Davis weather station remained on duty so I can tell you about the weather in Carwoola.

We recorded rain on 8 days in the month totalling 40.2mm.  This is effectively identical to last year and to the 6 year average.   The heaviest falls were 16.2mm on the 19th and 10mm even on the 20th.  After a very dry Autumn Winter is getting back to average or damper conditions.
In summary: yuck.  Only 1 day got above 15 degrees while 6 had a maximum below 10C.  The coldest minimum was -5.2 (not too bad) while a frost occurred on 21 nights, of which 14 were air frosts, below 0C.  I always dislike it when there is little difference through the day and on 13 days the range was less than 10 degrees with the smallest range being a paltry 3 degrees on the 15th.

This next chart compares the indoor and outdoor temperatures during the month.
We left for overseas on the 17th.  I find it informative how the temperatures change without our intervention.  I need to think a little about the way the maximum temperature indoors drops to track quite closely the outdoor maximum while the minimum is a few degrees above the external minimum.  Presumably this means that our house holds the heat a little better than the ground at the weather station, plus is sheltered from the wind.

This chart shows the daily maximum wind speed recorded on each half hour and the maximum gust recorded during each day. The system also records daily wind run but I have yet to contemplate how to interpret that metric.Although the gusts are considerably higher than the 30 minute spot readings the two series correlate well (r=0.83).  The similarity of pattern is also shown in this chart with the two measures plotted on different vertical scales.

Basically two very windy periods around 4th -5th and 19th to 22nd.

The second chart emphasises the fact that no half hour reading on the 14th showed any wind to be blowing which seemed a little strange so I checked back to the data.  Not only were all those readings zero but of the 48 gust readings (ie highest reading at any time during the half hour) 18 were also zero, 20 were 1.6km/hr, 9 were 3.2km/hr and 1 was the maximum of 4.2km/hr.  By any measure a very calm day.

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