High wind and graphs not the same???

[duke]

I rushed in tonight to see the high winds recorded after being battered on the south coast today. Strange thing though, the high wind recorded 10.5mph @ 13.58 is shown on the graph correctly. High gust recorded 24mph @ 15.16 but the graph shows only 18mph. In fact there were several gusts today over 18mph but the graph never showed anything higher than 18mph.

Next I opened "select a graph" and choose wind and here I find all the high gusts shown correctly.

What's going on? Should the 2 graphs not match?

Duke

[steve]

What's going on? Should the 2 graphs not match?

There's no particular reason why they should match, they're not necessarily showing the same data. It depends on which settings you've chosen and which data you are looking at. Bear in mind that your station does not actually supply anything that it calls a 'gust', so when you're looking at 'gusts' in Cumulus you need to be aware of exactly what you are looking at, and this depends on which settings you have chosen.

For example, do you have 'plot latest gust' set? Are you looking at 'wind gust' or 'peak gust' in Select-A-Graph?

Have you read this? http://wiki.sandaysoft.com/a/FAQ#The_pe ... eme_values

[Sunfish]

Whichever "settings are chosen", Cumulus still appears to send 'peak gust' data to the net--PWS, WU, CWOP, AWEKAS all recorded my highest gust today, whereas the graph did not. The only stations that didn't, were those accessing the realtime.txt file

So is the issue resolved by simply unticking the box, "plot latest gust?"

Apologies if this question is rather basic, but it would be useful to see the graph displaying the highest gust recorded at the station

[ironeagleuk]

So is the issue resolved by simply unticking the box, "plot latest gust?"

I have "plot latest gust" ticked, and my graph showed the maximum gust today

[Sunfish]

All the station data, including wind gusts, downloaded by Cumulus is recorded, stored, and displayed accurately, in the various record files, etc.

Also, it sends this accurate data to the net, including today's peak (maximum) gust.

It is only the graph display that does not replicate this, at least with my "plot latest" box ticked.

[steve]

The graphs are samples of the data; it is not feasible to plot every data point. 'Plot latest gust' causes the 'Latest' figure (as shown on the main screen) to be plotted. What this figure represents exactly depends on your weather station type. This figure may vary rapidly, e.g. on Davis stations, it changes every 3 seconds or so. The graphs are plotted once a minute, and hence, with Davis stations, for example, there is approximately a one in 20 chance of any given 'latest' figure actually being plotted.

Cumulus also stores the peak value of the 'latest' figure from the last 10 minutes. It calls this the 'gust', as this is a reasonable representation of a true 'gust' figure. If you untick 'plot latest gust', it will plot this figure instead. As it contains the peak figure from the last 10 minutes, and the graph is plotted once a minute, plotting this value means that the high gust figure will always appear on the graph.

Note that 'plot latest gust' is not the default value.

[Sunfish]

That really does answer my question.
Thanks very much for the detailed reply.

[duke]

I've now "unticked" the "plot latest gust option" and my graph now shows peak gusts.

Thanks for the advice.

Duke