Weather Related Organizations > PWSweather / AerisWeather / WeatherForYou
PWS Weather displays wrong barometric pressure value
Plug Nickel:
They claim they use the PWS's barometer.
From an email from them:
"We have different stations that send station pressure, altimeter, or mean sea level pressure. Our system will attempt to determine what version your station is sending based on the software. That said, currently, the PWSweather.com website displays the Mean sea level pressure."
weatherforyou:
WeatherForYou uses the raw data sent by your station's software, device or service. PWSweather has begun doing further processing to calculate and standardize the readings (based on sea level, I believe). I know the PWSweather.com developers are still working out some of the bugs in the conversions.
While WeatherForYou does get the data through PWSweather.com I take the raw data sent by your station as long as I've been requested to use that. If a request isn't made I'll still use data from PWSweather.com but it will include any calculated change that system makes.
Plug Nickel:
Barometric pressure measurements always confuse me.
The data that I'm sending both PWS and WFY is adjusted for elevation above sea level.
I know that PWS is using MSLP.
How do they differ?
galfert:
I think this may warrant looking at your VWS software configuration and also learning a bit more about your hardware.
What hardware is your station? What logger are you using? (I miss the that about the old PWSweather where it gave you information about the hardware used by the station).
I've never used VWS but I've glanced at the manual. It says that VWS will calculate Sea-Level Barometric Pressure. Hmmm...that is a clue right there. This means it is important for your software to have the correct elevation. It is also important to know more about your hardware. That is why I asked what is it? This might tell us what your station is passing to VWS. As it could be passing an already corrected pressure or it may be an uncorrected station pressure (QFE). I would also like to know if you have changed any of the setting in VWS in its calibration settings (Gain and Offset dialog settings). Hopefully the VWS Calibration setting is set to Gain 1.00 and Offset 0.00. I prefer to make these corrections at the console and never do these at the software level.
What I'm thinking is that you may be doing some barometric offset in VWS that you see on your software but it is not being passed to PWSweather.
Here is another issue that I see. This warrants looking into because I see that your VWS pressure along with what you see at PWSweather as being too low of a pressure to be accurate. I don't think your station is properly calibrated is what I'm saying. I'm looking at KBDU and KLMO and you are too low compared to them. Don't mention elevation differences (that is not an issue). I know people like to throw out elevation differences between them and the airport but that is not an issue.
Plug Nickel:
My station is a Davis Vantage Pro2 and it's got the correct elevation of 7300' entered (hence my low pressure reading).
Today my pressure is 29.72".
I have no offsets entered into anything since there is no official reporting station near me at my altitude for fine calibration.
VWS was getting pretty old, so I downloaded Weather Display software and the problem still exists.
It's reporting the corrected value to VWS as well as Weather Display and I Wire Sharked the packet it's sending and it's also sending the same elevation corrected value.
There's something going on with PWS Weather that's not occurring with WeatherForYou.
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