Topic: feels like

[m77]

from where does this statistic come?  i get the idea of there being a wind chill and a heat index, which is visible on the summary screen of the WL ip website, but at the mo my data reads

current temp 18.1C 64.7F
RH 82%
wind 2.6 mph
heat index 18.3C 65F
wind chill 18.3 65F

but then on the 'my weather' screen the feels like is 19C 65F??


is it due to rounding UP the Celcius ??  or is it the same as the F?

[DanS]

I always thought the 'feels like' was the same as wind chill when it's cold and heat index when it's hot. Both wind chill and heat index derived from the temperature, wind speed, and humidity. Possibly the station calculates 64.7 temperature, with the breeze and humidity figured in, bumps it up to 65?

[mackbig]

m77
The feelslike section of your testtags.php will look something like this.  This is mine right now...

$feelslike =  '26';   // Shows heat index or humidex or windchill (if less than 16oC)

$heati =  '19.8°C';   // current heat index
$heatinodp =  '20';   // current heat index,no decimal place
$windch =  '19.8°C';   // current wind-chill
$windchnodp =  '20°C';   // current wind-chill, no decimal place
$humidexfaren =  '78.5°F';   // Humidex value in oF
$humidexcelsius =  '25.8°C';   // Humidex value in oC

The feelslike value is rounded up.  It will be humidex or heatindex depending on which variable you set in WD.
I cant get to your site right now for some reason, so I cant look at what you are showing actually.

There is also logic in Ken's template that will only show Temp (during warm months) if the actual temp is not over 27.  I turned off this calculation because in Canada we report humidex when its material, and it possible with a raw temp of 21 to have a signficant humidex (around 30+)

Andrew

[m77]

Thanks guys.

I do not have a WD site, just a WL one. My user is maidenerlegh.

I would love to know at what points the wind chill becomes heat index according to WL.com

I know that NWS has its own cut offs but I can't find anything in the WL help files.

The reason I am asking this is I would like a simple feels like value on my site but to 1 decimal place, so I would like to know which to use under what conditions as the main feels like is rounded to the nearest whole unit.

[m77]

Well wikipedia seems to suggest the cutoffs are 10 and 27 deg C but the feels like value is still shown anywhere in between and sometimes at a different value to the air temp?

[m77]

http://www.wxforum.net/index.php?topic=5113.0 thread discusses thresholds but my question relates specifically to WL.com's use of them.

[Aardvark]

there is a calculation that explains it all

http://webpages.charter.net/rdgweather/THSW.htm

http://www.wxforum.net/index.php?topic=3169.0

[dalecoy]

http://www.wxforum.net/index.php?topic=5113.0 thread discusses thresholds but my question relates specifically to WL.com's use of them.

We could speculate for days, or quote other references - but I can't find any documentation about how the WeatherLink Network summary page actually decides what to post as "feels like".

So, perhaps you could email or call Davis and ask?

[m77]

there is a calculation that explains it all

http://webpages.charter.net/rdgweather/THSW.htm

http://www.wxforum.net/index.php?topic=3169.0

thanks, but that does not explain how WL.com decides what to post as its 'feels like' value and when. it refers to the THSW quite a lot which links to a console question - this measurement is not displayed at all on the WL.com pages.

i did look at the WL.com map to see other people's 'my weather' pages but i could really distinguish what was going on.

i will email Davis and wait a hundred years for an  answer.

[Aardvark]

there is a calculation that explains it all

http://webpages.charter.net/rdgweather/THSW.htm

http://www.wxforum.net/index.php?topic=3169.0

thanks, but that does not explain how WL.com decides what to post as its 'feels like' value and when. it refers to the THSW quite a lot which links to a console question - this measurement is not displayed at all on the WL.com pages.

i did look at the WL.com map to see other people's 'my weather' pages but i could really distinguish what was going on.

i will email Davis and wait a hundred years for an  answer.

If you are asking how WL.Com decides, I am sure it was up to someone given the task to design the site and put in what they wanted to put in.   One thing bugs me is that on my  page there  (http://www.weatherlink.com/user/dsmweather/index.php?view=summary&headers=1)  I don't have the option of not putting in sensors that no one but me know what they are.  Again,  the decided  idea is up to their web master.   I am sure that there is a limit to when that value kicks in and wind chill drops out.   On my site, I always list the THSW, the THW and the wind chill  and heat index so we have the whole taco.

I believe it kicks in at 63F / 17 C;

[m77]

On your black signature you just have "feels like", aardvark.

What exactly is that value?

I have tried looking at some wind chill values in new zealand Weatherlink stations and heat indexes in florida to see if I could spot some thresholds, but I could not.

[Aardvark]

the THSW value

http://www.weather-watch.com/smf/index.php/topic,1542.0.html

above is another link.. I suppose the best idea would be to contact Davis directly.  I sent them an email on Wednesday and still waiting.  I suppose if it wasn't expensive, to call their tech support number and talk to them on the question.

You can always google or bing or something your question , changing the parameters of the question until you find something out there that  tells the answer. 

IF you do find out, publish it here.

OH... I some times use the Humidex as well,  but the THSW always gets the wife to turn on the air conditioner.. 

[m77]

Thanks, I do not have solar data so could not calculate that value.

I have emailed davis and will post here if I get a response.

[BigOkie]

the THSW value

http://www.weather-watch.com/smf/index.php/topic,1542.0.html

above is another link.. I suppose the best idea would be to contact Davis directly.  I sent them an email on Wednesday and still waiting.  I suppose if it wasn't expensive, to call their tech support number and talk to them on the question.

You can always google or bing or something your question , changing the parameters of the question until you find something out there that  tells the answer. 

IF you do find out, publish it here.

OH... I some times use the Humidex as well,  but the THSW always gets the wife to turn on the air conditioner.. 

Srsly?  Does it cost to speak with tech support for Davis?

[Aardvark]

the THSW value

http://www.weather-watch.com/smf/index.php/topic,1542.0.html

above is another link.. I suppose the best idea would be to contact Davis directly.  I sent them an email on Wednesday and still waiting.  I suppose if it wasn't expensive, to call their tech support number and talk to them on the question.

You can always google or bing or something your question , changing the parameters of the question until you find something out there that  tells the answer. 

IF you do find out, publish it here.

OH... I some times use the Humidex as well,  but the THSW always gets the wife to turn on the air conditioner.. 

Srsly?  Does it cost to speak with tech support for Davis?

sometimes

[kray1000]

Srsly?  Does it cost to speak with tech support for Davis?

sometimes

You're kidding, right?  Who do they think they are, a software company?  (WeatherLink doesn't qualify.)

[BigOkie]

the THSW value

http://www.weather-watch.com/smf/index.php/topic,1542.0.html

above is another link.. I suppose the best idea would be to contact Davis directly.  I sent them an email on Wednesday and still waiting.  I suppose if it wasn't expensive, to call their tech support number and talk to them on the question.

You can always google or bing or something your question , changing the parameters of the question until you find something out there that  tells the answer. 

IF you do find out, publish it here.

OH... I some times use the Humidex as well,  but the THSW always gets the wife to turn on the air conditioner.. 

Srsly?  Does it cost to speak with tech support for Davis?

sometimes

Wow.  So you spend upwards of $500 PLUS whatever extras you have on the Davis Stations (VP2 here as my point) and they want you to pay MORE for support for it?

Just....just.....

...wow.

[PaulMy]

I haven't called Davis often but there has not been any mention about cost for support.  Last time 2.5 years after I bought my VP2 and was for help on setting up my Weatherlink webpage - about 45 min. of actual telephone discussion and no rush on their part to cut it off.  Can say that I am quite pleased with their phone support.

Paul

[SlowModem]

You're kidding, right?  Who do they think they are, a software company?  (WeatherLink doesn't qualify.)

good one!   

[mackbig]

If you live in the Bay area of Cali, its free to talk to Davis Customer service. 17.3 pence per minute for m77 if he's using BT.

Andrew

Srsly?  Does it cost to speak with tech support for Davis?

[m77]

while i wait for that email (i have spent around a fiver on more crucial calls to Davis so will wait on the email for this query!) I have done a bit of research.

I used the WL.com map at http://www.weatherlink.com/map.php to sample 33 stations from around the world with a good spread of air temperatures. I recorded the data in a spreadsheet and then looked at a few ways in which the 'feels like' temp could have been worked out.

Heat Intensity - rounded to nearest whole, rounded up and also down
Wind chill - again to nearest, up and down.

I then highlighted the cell that was spot on, in yellow.

the green column shows the 'temp' displayed on the blue screen called 'my weather' and the yellow 'feels like' is the statistic from the same screen - this is the one that i am trying to figure out how the heck Davis get it.

If you look at the attached sheet it seems for the higher temps (the sheet is sorted by the temp displayed) the heat index rounded to the nearest whole comes out on top.

For lower air temps the Wind chill rounded to the nearest unit is a better fit but it is a real hotch potch with no real rule.

One suggestion is that the 'my weather' page updates a little later and that may explain why there are a few readings that are 1C out.

Any thoughts?

[m77]

Upon further inspection, does this generally support previous discussion that wind chill kicks in at 10C and below and heat index kicks in at 27C and above?

Most feels like temps are the same as the air temp between 11 and 26C although I would like to look at more temperatures in the mid to high 20s to see if this idea holds up.......

[m77]

i think this may have some answers.

  http://www.davisnet.com/product_documents/weather/app_notes/apnote_28.pdf

the more i read it, the more i think that 'Feels like' is not a cut and paste of either wind chill or heat index and is something more mathematical.

[Aardvark]

right now it is 85, and the thsw is 102, but the humidity is 63% and the solar is at 659 w/m2   .. it is the Steadman calculation...

[m77]

So it is the heat index?

But why are there instances in my table of the heat index not being the same as the feels like? Even at high temps?