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Pressure readings CumulusMX and wxnow.txt

Topics about the Beta trials up to Build 3043, the last build by Cumulus's founder Steve Loft. It was by this time way out of Beta but Steve wanted to keep it that way until he made a decision on his and Cumulus's future.

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falkunmalti
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Joined: Thu 09 Oct 2014 4:19 pm
Weather Station: Oregon Scientific WMR200
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Pressure readings CumulusMX and wxnow.txt

Post by falkunmalti »

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
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steve
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Re: Pressure readings CumulusMX and wxnow.txt

Post by steve »

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: 106
Joined: Thu 09 Oct 2014 4:19 pm
Weather Station: Oregon Scientific WMR200
Operating System: Windows 10, Raspberry pi
Location: Ontario, Canada

Re: Pressure readings CumulusMX and wxnow.txt

Post by falkunmalti »

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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