This seems to come up periodically, but I’ve been scouring these forums and weewx discussion group, and can’t find a good solution. I’ve recently installed my Tempest and I’m using WeeWX to upload to PWS Weather. I understand the difference between station pressure and sea-level pressure, but I can’t get the WeeWX and PSW Weather pressure (reported as barometer/sea-level pressure) to match what is shown in the WeatherFlow app and web page (and sent from WF to Weather Underground).
The WeeWX/PSW Weather barometer value is always about 0.1-0.2 inHg lower than the WF Pressure (sea level) value. For example:
WF “Pressure”: 30.003 inHg
Weather Underground: 30.00 inHg
WeeWx “Barometer”: 29.925 inHg
PSW Weather “Pressure (MSLP)”: 29.84 inHg
WF “Station Pressure”: 28.972 inHg
At first, I thought this might be an elevation vs. elevation+AGL issue. My station is 957 ft above sea level, and 8 ft above ground level. At first, in WeeWX and PSW Weather, I reported the elevation as 957, but then changed it to 965 (957+8). Still, no luck.
Is this just a basic difference in how the services are calculating SLP, even given the same station pressure and elevation (and temp, humidity)? If not, what should I fix?
What is the right answer for what to report as ‘elevation’ in WeeWX and PWS Weather? The WF ‘Elevation’ or elevation plus height above ground?
Thanks for any help you can provide!