Trend in Last Hour question

[RayProudfoot]

Steve,

A cold front has just passed through here and the temperature in the last hour has dropped from 12.1 at 13:20 to 7.1 at 14:20.

However, the Trend in Last Hour shows -1.5C. Shouldn't it be -5.0C?

[steve]

It's the average over the previous three hours.

[RayProudfoot]

It's the average over the previous three hours.

Looking at my temperatures over the last 3 hours I can see how you've arrived at -1.5C.

14:20 - 7.1C
13:20 - 12.1C
12:20 - 11.5C
11:20 - 11.6C

11.6 - 7.1 = 4.5 / 3 = 1.5

Is this the way it's done officially because it's not really giving the right answer is it? It should show -5.0C

Is there any way you could change it to reflect the actual change in the last hour? Any big changes in temperature are going to evened out by calculating the change over 3 hours and taking the average.

[steve]

Is this the way it's done officially because it's not really giving the right answer is it? It should show -5.0C

It's the right answer, because it's a rate of change, not the change in the last hour (compare rain rate and rain in the last hour). I don't know if there is an official period over which temperature change is quoted, I couldn't find one. Pressure changes are usually forecast/quoted over a three hour period, so I chose to do the same with temperature, converting them both to rates rather than the absolute amount over the three hours.

I don't propose to change it, but there's no reason why an additional figure (again, like rain rate and rain in the last hour) shouldn't be added as an enhancement to a future version.

[RayProudfoot]

I don't propose to change it, but there's no reason why an additional figure (again, like rain rate and rain in the last hour) shouldn't be added as an enhancement to a future version.

That's a good solution. I would like to show dramatic changes when they occur and this seems to be the best way to achieve it. I shall raise an enhancement request later on.

Thanks.

[RayProudfoot]

I have submitted an enhancement request Steve.