Monday, 3 March 2014

A month of 2 halves: February '14 Weather report

I will begin with my memory, uncontaminated with data,  of the weather in February 2014.  The first half continued the hot and arid conditions evident in January.  Very good rains appeared mid month, after which the temperature calmed down and cloudy days finished the month off.

Having got that off my chest let us see what the weather station tells us.

Rainfall

Measurable rain came on 5 days (although only 3 of them were significant) totally 84.6mm. \
That has been the subject of a separate post.  The most surprising aspect of this was the way there was very little run-off during the event, and the way the Creek stopped running within a few days.  Obviously the moisture has gone into the soil!

Looking at the rain in comparison with other periods gives a rating of 'reasonable'.

Temperature

Fortunately, the data supports my memory.  Last month as well as doing a report on what had happened, I posted about some possible alternative ways of presenting the temperature elements of the weather reports.  Being totally a caring and sharing SNAG (not) I consulting a few other readers on the choice between ways of doing this.  Most of the responses were along the lines of "We trust you to choose.".  You are very kind (and possibly optimistic)!  So I have chosen.

This needs a little explanation before getting to the interpretation.  
  • The green lines represent the range of temperatures during the day with (obviously) maximum at the top and minimum at the bottom;
  • The yellow boxes are days in which the temperature at 0:30hrs (bottom of the box) was cooler than the temperature at 23:30hrs (top of the box);
  • The blue boxes are days in which the temperature at 0:30hrs (top of the box) was warmer than the temperature at 23:30hrs (bottom of the box);
  • A dash crossing the vertical line means 0:30 and 23:30 temperatures were the same.
Readers did say they trusted me!

Interpretation

Clearly the temperatures were warmer up to the 11th and much cooler thereafter.  After the extreme heat of 1st to 3rd there was a temporary plummet on the 4th with the maximum temperature at 0:30 and the minimum at 23:30 (thus the box fills the range).

The very limited range, and change, of temperature on the 14th shows the insulating effect of the cloud cover and rain on that day.

As would be expected the boxes(or dashes) are generally towards the bottom of the bars, since night time temperatures are usually cooler than daytime temperatures.  However they are not, in most cases at the bottom of the lines as the temperature continues to cool through the dark period with minimums usally occurring around 05:30.

Humidity

This is almost a case of "move along folks, nothing to see here."
Quite low humidity apart from the rainy period in the middle of the month and the cloudy period at the end.  (As an aside, the cloud cover of the last few days have meant that the solar powered fairy lights and snake repellers ceased operation for a couple of days.  Fortunately the snakes also seemed to have ceased operations!)

Wind

It didn't seem to be an unduly windy month: the following chart shows both January and February lines, with the Maximum gust in a day as the variable.
Indeed they are about the same level, with slight differences in distribution of peaks and troughs.  The arrival of the rain mid-month stands out!

By far the majority of the gusts came from the NE - SSE range.  (This accords with my memory: when it is hot one hangs out for the cooling Easterlies.)

Evaporation

As explained last month these data relate to Burrinjuck Dam ad are thus even more indicative-only than the rest of these numbers.  Here is a graph showing the two months daily evaporation.
Basically all over the place.  It is interesting that the rainfall at Burrinjuck was much greater than Carwoola (not surprising as it is on the windward side of the mountains) and came close to matching the evaporation in February.  The latter averaged 6.4mm per day in February compared to 7.3mm per day in January.

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