Responding to both of your messages: You are right that my comments would
equally apply to the heat index being different to the actual temperature.
A relatively quick scan of the relevant pages on the NWS site found the
explicit statement that the wind chill was undefined for air temperatures
above 50 ºF but I did not notice the slightly less strongly worded caveats
about heat index calculations being unreliable below 80 ºF
My console initially showed the same value (60) for Heat index and Wind
Chill, with outside temperature 62.0, RH 60, and wind in the low teens. At
the same time, the weewx display showed a wind chill of 62.0 and a Heat
Index of 60.7. A couple of minutes later, the temperature had dropped to 61
7, the RH had risen to 61, the heat index had risen to 61 (all on the
console), with no significant change in the wind. The simultaneous weewx
value for heat index was 60.5. It looks, therefore as if weewx is not using
the console's calculated values for *either* derived parameter..
In terms of definitions, at least as per the US NWS, it is not that (wind
chill == temperature) above 50 ºF, but that wind chill is *undefined* above
that temperature.They are not quite as clear about heat index, simply
saying that "...The Heat Index calculation may produce meaningless results
for temperatures and dew points outside of the range depicted on the Heat
Index Chart linked below {40<= RH <=100; 80<= ºF <=110)}
All my 'derived value" options in weewx.conf are set up "prefer_hardware',
so weewx should presumably be using those transmitted by the console. As
far as I can see, it isn't - certainly not for Wind Chill, and probably not
for heat index, either!
On Friday, November 6, 2020 at 3:25:32 PM UTC-5 Greg Troxel wrote:
>
> Also, check the values in your skin against what is on your console.
>
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