Friday, 2 June 2017

Weather report May 2017

At an early stage in the month a comment was made to the effect that May was an uninteresting month as it wasn't hot, but not really cold, and there was little rain.  Those attributes were evident this May, but it is still interesting to see see how the month sits within the year and how this May compares with earlier Mays.

For most measures the month was indeed close to average (possibly the number of average readings was above average?).  The exception was minimum temperature which was for the 4th month this year well above average.


The month ended with a total fall of 35.4mm: a little below last year and the 33 year average, but above the average for the 10 years we have lived here.
It is noteworthy that 29.6mm of this fell on the 19th or 20th of May.  The rest of the month was very dry.  However the water seems to have got into the soil and Whiskers Creek has run through the month.

The year-to-date fall continues to catch up from the deficit of the very dry January and February: we're now at 64% of the average.  However a pro-rata estimate of the annual total is still only 457mm, which would be the lowest recorded in the 10 year period and the second lowest for the 33 year period.  As the BoM forecasters are muttering about a dry period coming up we could set a record!


A mild start to the month was followed by dropping temperatures towards the end.
 Looking at the long term averages May continued the year's pattern of maxima close to or below average  ....
 .. with minimum temperatures well above average.
The big-ticket item in Winter is the number of frosts.  As with previous months the two measures are temperatures below +2oC  (a ground frost) and temperatures below 0oC  (an air frost).  The first two charts below show the number of days meeting those criteria in 2017 and the 24 year average.

Clearly the number of frosts is below average for both measures.  That is emphasised by looking at the values for 2017 as a % of the average.  Clearly we have been very deficient in deficiency of warmth.


As always I take the relative humidity reading for 3pm as my indicator.  As usual the graph looks like a cross section of the Himalayas, but note that no day was below 40% or above 90%.   A pretty bland month.
The comparison with longer term average  - in this case 5 years - shows, somewhat surprisingly in view of there only being one major rain event,  that the month was slightly above average for humidity.  That justifies my subjective view of it being a rather drab month: no rain but cloudy.


As usual I am unsure about the quality (somewhere on the continuum from poor to useless) of the wind data due to poor location of my weather station.  However the average gust for the month was quite low.

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