Wind Chill/Heat index

[J Jones]

I was just wondering if the wind chill is working correctly. I have never had heat index lower than wind chill.

Version 4.5.1

[p q]

see discussion here: https://github.com/weewx/weewx/issues/601 

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Peter Quinn
(415)794-2264

[Tom Keffer]

I would also call your attention to option "algorithm". It allows you to use the "old" algorithm, which many people prefer (including myself).

http://www.weewx.com/docs/usersguide.htm#[[[heatindex]]]

[StdWXCalculate]

  [[WXXTypes]]

    [[[heatindex]]]

      algorithm = old

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[J Jones]

Thanks! it hasn't been that cold here since the beginning of the year. I was thinking they were reversed.

[J Jones]

Hi it's me again. It doesn't look like wind chill is on the graph. We had a low wind chill of 25 today and its not showing on graph.

[Tom Keffer]

But, you didn't have any wind! It's the wind that counts, not wind gusts. Your wind was less than 2 mph. Wind chill doesn't kick in until the wind is greater than 3 mph.

https://www.weather.gov/safety/cold-wind-chill-chart

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[J Jones]

I guess I'm just not used to the new format. It shows a chill on the left of 25 and  the graph shows roughly 35.

[Tom Keffer]

I admit, that is a bit confusing.

If the loop_hilo option is set to true (which is the default), then LOOP packets contribute to the daily max/min values. So, if a value is reached, even if only for a second, it will appear in the highs and lows. In other words, the gusts do count. OTOH, the plot uses the average values over an archive interval, so gusts will not contribute much.

Hope that makes sense. 

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