Friday, 1 February 2013

Weather Report for January

I have posted a few times in the month about significant weather events but thought it worthwhile putting up a general overview of the month.

The following graph shows the outdoor temperatures for January.
In a word, HOT!  11 days recorded a maximum temperature over 35C, topping out at 41.4 on the 18th.  I was surprised to find that there were 8 days in which the minimum temperature was below 10C, with 6.8C on the 14th being the low point.

The next chart  compares December 2013 and January 2013

I am currently looking at two measures of 'windiness'.  These are maximum gust in the day and average speed through the day.  Maximum gust is LH Axis and daily Average is RH axis.
Clearly the picture is very similar, especially on very windy days.

With regard to wind direction this pie Chart shows that most of the wind, in terms of number of times the direction was reported, in January came from NE to SW inclusive.
 This was a bit surprising as I think of the wind primarily coming from the NW.  I wondered if this was a factor of daytime winds coming from the NW while overnight the influence of the coast gave a predominance to the Easterly directions.  This next chart show that the "whole day" and "7AM to 7PM" directions closely correlate,
There is also close correlation between the number of readings from a direction and the sum of windspeeds from each direction.  Some further empirical research (ie go and look at the direction the wind is coming from and compare this with what the weather station is reporting) is needed to resolve this breach of conventional wisdom.

We received 102mm this month, the highest in the 7 Januarys for which I have records.  However rain was only recorded on 5 days with one day recording 64mm.  Overall the period felt very dry.

Looking forwards
As well as sorting out the issue of wind direction I'm going to try to develop some indicators of how the day felt overall and fire risk.  These will be simpler than the official indicators of that type which seem to involve such tricks as an exponent based upon the 4th root of the number you first thought of.

1 comment:

Denis Wilson said...

Good post, Martin.
Yes, a month of extremes. Very hot days, interspersed with cold days and colder nights.