Settings - Weather
LiveTraffic can set X-Plane's weather based on METAR and RealTraffic weather data
In X-Plane 12 and later, LiveTraffic can modify your in-simulator weather based on METAR information or RealTraffic weather data.
X-Plane's weather model changed significantly with X-Plane 12. Hence, the weather injection feature is only available in XP12, but not in X-Plane 11.
X-Plane's built-in real weather feature is actually quite powerful already. And maybe you won't see much of a difference in some places or in some weather situations. But there have been enough examples in the past where weather based just on METAR seemed to be a bit better reflecting reality and hence LiveTraffic offers to do so.
If you happen to have a RealTraffic license, then you can inject weather based on their data, which they claim is more detailed both in terms of spacial as well as time resolution. Yet, the data remains modelled data based on a limited set of measurements across the globe, so it cannot correctly reflect every cloud that there is.
Configuration
Set Weather
"Off" or "RealTraffic" (see below)
Select if you want LiveTraffic to control X-Plane's weather, and from which source, see next sections METAR+XP and RealTraffic
Use METAR up to
5,000ft AGL
Height above ground level up to which METAR-based weather takes priority
Max. METAR distance
25nm
Use METAR up to this distance away from the field it was reported for
Set weather to
Paste a METAR text here and hit <Enter> to have the weather set accordingly, see below.
The default for Set Weather is determined based on your current weather setting when starting LiveTraffic for the very first time. If you at that time run with X-Plane's real weather and you have a RealTraffic license, then the default is "RealTraffic". In all other cases it is "Off".
METAR + X-Plane real weather
The Set Weather mode "METAR (near ground) + X-Plane real weather" is available to everybody. It uses METAR information downloaded from public web site aviationweather.gov that LiveTraffic requires anyway for barometric pressure information to correctly assess a plane's altitude.
Start your X-Plane flight already with X-Plane's real weather turned on for best results.
When you are flying low (less than what's configured in Use METAR up to as a height above ground level) then LiveTraffic generates weather based on the METAR. That works particularly well for visibility, clouds, wind, and rain.
When you are flying high, or when there is no METAR nearby (closer than what's configured in Max. METAR distance), then LiveTraffic activates X-Plane's real weather.
LiveTraffic shows a brief message in the Message Area when it switches between these two modes.
RealTraffic weather data
The Set Weather mode "RealTraffic weather data" is only useful if you have a RealTraffic license and activated the RealTraffic channel to receive weather data.
In this mode, LiveTraffic mixes METAR data (this time received from RealTraffic) with global weather model data that RealTraffic also provides, to fully control X-Plane's weather at all times.
METAR information is used as long as a nearby report (closer than what's configured in Max. METAR distance) is available. The Use METAR up to setting only influences a few selected weather phenomena, for example visibility, which is a global setting in X-Plane and is fed from METAR if flying low and from the weather model data if flying high.
Set Weather to Specific METAR
You can copy and paste a METAR text into the Set weather to field, then hit <Enter>, and LiveTraffic will modify X-Plane's weather to match this METAR. Effectively, this is a short-cut to configuring weather manually in X-Plane's weather settings. The weather will stay constant.
When using this option, then the entire weather in all atmoshperic levels is set as per the METAR. So the wind is the same at all altitudes as is visibillity. Temperature is calculated to decrease with higher altitudes by a constant factor. This is unrealistic for high altitude cruising as a METAR only describes weather close to the ground, but is good for simulating weather situations during take-off and approach.
Once the weather is set this way, LiveTraffic no longer touches it. The Set Weather source is actually changed to "Off". So you could even go into X-Plane's weather settings and further fine-tune the weather, e.g. by changing high altitude winds.
Limitations
The generated weather bases on data like METAR or global calculated weather models. Not on your view out of the window. Please don't expect to see the very same cloud patterns. It will not 100% accurately reflect real weather but is an approximation.
A METAR is typically reflected fairly well in the injected weather. But there are common misconceptions like that a "CAVOK" report would not allow for any cloud in the sky. CAVOK actually only defines "no cloud of operational significance", which typically translates to no clouds below 5,000ft AGL. So while you can expect no clouds between you and the airport during approach, there can very well be clouds above you all the way up to 100% coverage.
There have been reports that METAR and RealTraffic's global weather data didn't agree on the cloud cover with METARs in a region saying none (NCD) while the global weather model data had clouds even on fairly low levels. We will monitor such cases to see if the weather data interpretation can be improved.
The Weather Parameters LiveTraffic Controls
X-Plane 12's weather model allows for quite a number of parameters to set. Here is a (too) brief introductory post by Laminar when introducing it, this YouTube clip might be more interesting.
LiveTraffic tries to set nearly all available parameters. The most important ones are typically well reported in a METAR and in RealTraffic's weather model, like visibility, clouds, wind, precipitation. But there are limits.
For example precipitation: The amount is given, but information of the type is scarce. Is it rain? Or snow? Or sleet? A good METAR may have that. The global weather model data used outside of METAR coverage doesn't say anything about it. So LiveTraffic needs to take guesses.
And then precipitation collects on the ground and affects your runway condition. X-Plane has lots of variances what it can show on the runway. But neither METAR nor global weather data provide that information. So again, LiveTraffic needs to take guesses.
Similar with wind: Direction and speed are well defined, wind shear is reflected less well but may appear in METARs. Turbulence is not given in a METAR, but in RealTraffic's model data, but in a different unit than X-Plane uses...
Here's an output (see Settings > Debug > Log Weather) of the weather parameters LiveTraffic controls, in this case in "METAR+XP" mode, after applying a METAR (given in the last line) has been applied over real weather:
Support, Bug Reports
The weather feature is very new, introduced in v4.0 (and the reason for the major version bump). So it will have bugs. If you want to help improve the feature please turn as usual to the Support Forum. I expect many post á la "METAR says this but what I see is that". Understand what METARs describe and what not, especially that they describe weather near the ground only. I find this IVAO documentation page helpful to understand all METAR elements.
For weather-related support posts please include:
As with every bug report: Expected result and actual result and why you aren't happy with the actual result specifically.
Enable both Set Log Level = Debug and Log Weather in Settings > Debug > Logging. This will put detailed weather information into the
Log.txtfile for later analysis, the kind of output showcased above, whenever LiveTraffic injects weather parameters into X-Plane.You can also at critical moments click the [Log weather now] button.
Screenshot of the Status / About page as it summarizes current status of weather generation.
Screenshot of the actual weather you see in X-Plane.
Screenshot of X-Plane weather customization dialog
In response to your request I may even ask you to enable Log Raw Network Data in the Debug settings, which will create a new file named
LTRawFD.log, which logs each response by the data provides, ie. also the raw data LiveTraffic receives from RealTraffic to build weather from.
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