Does OpusFSX use the cloud coverage in Canadian METARs after RMK? i.e. METAR CYHZ 031700Z 34008KT 15SM -SHRA FEW015 FEW030 OVC048 02/01 A2995 RMK SF1SC1NS6 SLP148=

 

I thought I read somewhere that OpusFSX doesn't look at anything after RMK in METARs.

 

Thanks,

 

Mike

That's correct, Opus doesn't look beyond the RMK section it just decodes the actual report.

 

Stephen

 

But it looks very interesting so I might add it. I could check for the Canadian style RMK and decode it if specified and validated.

 

Regards

Stephen

Thanks for the answer. It would definitely add to the accuracy of Canadian METAR to implement it. I have also seen it at some other large airports in other countries. RJAA has something similar and so does BGBW although I can't seem to find anymore airports by just browsing skyvector.com.

Of course I will have to take into account the limitations within FSX, of which there are many, but the cloud layer descriptions will provide excellent guidance in cases where it is provided.

 

I have already added it to the 'to do' list.

 

Stephen

I have also noticed in Canada there are a lot of small automated weather stations that might have a report like "CXKT 141500Z AUTO 27004KT 13/09 RMK AO1 SLP263 T01320087 58010". After RMK it lists the sea level pressure of 1026.3mb, Opus reports the station as not having an altimeter setting associated with it so it defaults to 29.92 which really messes up the pressure gradient. You can really see this by using the Opus Assistant and the Surface QNH view. If it isn't possible to get the correct altimeter setting from the station's data, maybe it would be better not to default to standard pressure and just interpolate it from nearer stations with correct altimeter settings?

 

 

It does interpolate and average the surrounding QNH pressures. The METAR would be flagged as having no reported QNH and so would be averaged with the surroundings. The weather Interpolator will also weed out obvious erroneous reports most likely from faulty AUTO report centres.

 

It is the QNH pressures that are important to pilots, not the SLP that's why no other countries bother reporting SLP in the remarks except for Canada, USA (occasionally), and I believe one other.

 

There is a difference between sea level pressure (SLP) and altimiter setting (QNH). Specifically, SLP includes consideration of the actual temperature, while QNH does not. The QNH value is what you would dial into the altimeter in an airplane to make it read correctly on the ground at your location. Be aware that pressure readings you get from airports are QNH -- not SLP. This is because they need to tell pilots where to set the altimeter.

 

Its the setting of the Altimeter bit that is important !

 

Stephen

 

P.S.

 

The SLP may be important and included for other meteorological services but is not important to pilots. Hence, it is relegated to a remarks section simply to provide additional meteorological related information from that met centre. Not sure why or who would use this info but it is not really of interest to the LWE. We also may have other sources of information available soon but in places where there is reasonable METAR coverage the averaging should be fine for government work.

 

Stephen

 

After the LWE Interpolator averages the QNH with the surroundings what you see on the map is what is injected into the sim so your altimeter setting will be correct. At the end of the day that is all that matters, your altimeter is set in accordance with the simulators QNH at your destination, that way you will fly the correct descent path and not fly into any terrain or infringe other airspace.

 

Stephen

I have made a note to see if I can convert SLP into QNH in cases where no QNH has been reported in the METAR.

 

Stephen

Thank you for all the detailed explanations and taking the time to write them Stephen.

 

I have noticed another thing though. It seems like the stations that do not report cloud cover never have clouds above them and that is evidenced by looking at the live weather assistant and by just flying near them. Is there anyway to disable weather stations so I could test it out and see if I get more cloud coverage?

No need to delete them, I will introduce a marker indicating there has been no cloud statements included in the METAR, that is no CLR, CAVOK, or specific cloud layers etc.., then the LWE Interpolator will just use what parameters have been reported, and allow the cloud to bleed across from adjacent cells where it has been defined.

 

Stephen :-)

Great! Thanks a lot Stephen!