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Pressure readings CumulusMX and wxnow.txt

Discussion of version 3 of Cumulus, which runs on Windows, Linux, and OS X. All Cumulus MX queries in here, please.

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falkunmalti
Posts: 39
Joined: Thu 09 Oct 2014 4:19 pm
Weather Station: Oregon Scientific WMR200
Operating System: Windows 8.1
Location: Ontario, Canada

Pressure readings CumulusMX and wxnow.txt

Post by falkunmalti » Thu 09 Nov 2017 5:23 pm

Hi

I wonder if someone can help. I have noticed a large difference in the pressure readings displayed in the CumulusMX gauges and the number copied into the wxnow.txt. For example right now, the reading on the gauge is 1008, which does agree with the Oregon Scientific Weather display, but the number copied into the wxnow.txt is 1017.5. Is there any reason why the two numbers should differ? The other numbers seem to be ok.

Thanks in advance.

Joe
VA3JLF

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steve
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Re: Pressure readings CumulusMX and wxnow.txt

Post by steve » Thu 09 Nov 2017 6:06 pm

As noted in the wiki page about the wxnow.txt file, the pressure in wxnow.txt is altimeter pressure rather than MSLP (as that’s the way CWOP want it). Altimeter pressure is calculated from the absolute pressure from your station and your configured altitude.
Steve

falkunmalti
Posts: 39
Joined: Thu 09 Oct 2014 4:19 pm
Weather Station: Oregon Scientific WMR200
Operating System: Windows 8.1
Location: Ontario, Canada

Re: Pressure readings CumulusMX and wxnow.txt

Post by falkunmalti » Thu 09 Nov 2017 10:00 pm

steve wrote:As noted in the wiki page about the wxnow.txt file, the pressure in wxnow.txt is altimeter pressure rather than MSLP (as that’s the way CWOP want it). Altimeter pressure is calculated from the absolute pressure from your station and your configured altitude.
Thanks Steve, I knew there had to be a reason for that.

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