How the FS 2004 Weather Engine Works?

[Guest in_04]

Hi Bruce,I know the US-Airports report much more METAR data than the German ones. I didn't know that all Kxyz airports will report, so thanks for the info.I didn't mean that at McCord a human make the mistake, I read a thread here (sorry didn't have the link) of a person which lives near the base is saying that there is more than 7 miles visibility. I also have METAR reports at my own, who show 7 miles for McCord and 10 miles for Tacoma/Narrow, Seatac and so on. So the other person, not I ,guess that there could be a problem with the McChord equipment.The German station which is constantly wrong in the downloaded Jeppesen weather, is very near to me and the METAR report shows a visibility above the 10 miles (50 km), so there IS a problem in the Jeppessen/Microsoft data.Are you shure that FS2004 set the visibility to 10 miles max?I think it didn't set the visibility to 10 miles for the reported stations, even if station reports 10 miles. But maybe it is FSUIPC who make the changes. So far I remember FS2k4 set the visibility between 10 and unlimited on random(?) basis if the station report 10 miles, but maybe I forgot the out of box handling, because I didn't use the FS2k4 downloaded weather.ByeMarkus

[Guest in_04]

>This is a major annoyance of mine if FS9 and I can't wait for someone's weather program to filter these visibility changes out.>I guess that could be very hard, the problem is that the visibility around the airplane is set by FS2k4. So the weather program can change the visibility for the wx station, or change the overall visibility. But at which point FS2k9 will switch between different station is currently unknown.For my wx program I set the upper altitude of the visibility to low altitudes (below the lowest cloud layer). But sometimes i got the switching from 10 miles vis to unlimited and back in less than 30 seconds.A place where I often get those changes are Tacoma Narrows.ByeMarkusPS: Maybe you have a idea to make the visibility change smooth?

[Guest in_04]

Hi Claudius,you still use FS2k2?I could do it, but there are some known problems (crashes) and some missing features in it. Because I didn't have the time to make a version for Fs2k2 and Fs2k4 I stoped every development of the FS2k2 program. But if you whant I can give you the source code as well (it is MS Visual C++, Version 6.0)Send me a PM mail.ByeMarkus

[Guest in_04]

Hi Barry,I don't think that you hit a dead cell zone over the US. There are only very few ones, around Mt. Rainer(?) is one but the interpolation of the surrounding stations work well. The fog bank is 100% a problem of FS2k4, they forgot to make a visibility transition between the stations. They done transition for wind, temps, pressure and the rest. But the visibility is always the nearest wx station. Currently I talk to Pete, the FSUIPC creator, if there is a possibility to influence the airplane visibility with my wx-program, but currently he only implement a function for graduate transition depends on the altitude. I also never have a fog out of nothing phanomen seen in my real world flying expierence, but in Fs2k9 it is there. Belife me I work on it to find a way of workaround it.Currently I have one idea, but the tradeoff would be, that you lost the ground haze feature of FS2k9, which looks nice for foggy stations. ByeMarkus

[Guest in_04]

Hi Gabriel,the speed of changes in the meteorological conditions is hard to determine. There are many features which show a rapid weather change we didn't have in the METAR report. First one is the barometric pressure of the past and moving fronts.So if you have stabil high pressure weather you could set the FS2k4 dynamic weather to "none" or "mild".For the rapid changes of Low pressure weather, often seen in the spring and autum (here in Germany), you could use the "fast(?)" and "rapid(?)" settings. The "medium" setting is what the name says, something between rapid and mild changes.I don't know if this weather behaviour is correct for youre country, but here in Germany the High pressure systems are very stabil and produce less weather changes over the day. In low pressure situations the weather change at a fast rate over the day.But for GreatBritain, esp. Scottland or Ireland, I would use the higher settings every time. There the weather changes every 15 minutes :-)Hope I answer youre question right.ByeMarkus

[Gridley 257]

>PS: Maybe you have a idea to make the visibility change>smooth?The only solution I can think of is parsing the data set to make sure neighbors show some correlation in visibility and throwing out or averaging the outliers...

[brucek 38]

Hi Markus,No- I'm not sure that FS2004 sets the vis to be what's reported. But if it did, then you'd get almost all the time 10 sm vis max, puncuated by small periods of other vis values that could be greater then 10sm (as you passed over a Class B,C or D airport). If the vis distance is truely a horizontal distance (and not slant range distance), then 10sm at altitude is going to look very murky close up on the ground below.Obviously the chances of finding a higher density of Class B,C and D airports is greater in the eastern half of the US and in California in the west.I'm at work, but here's an example in my area. My home airport is KBJC (Jeffco), a Class D. An hour's flight in a C172 (so not far) to the north will take you to KCYS (Cheyenne, WY), also a Class D airport. In the morning hours at this time of year, chances are you'll get 70sm vis reported. Half way on this trip is KFNL, an airport with Class E to the surface, and which has an AWOS (or could be ASOS, I can't recall). This will report 10sm vis max. So, in a short flight, you can see the transition from a human interface to a computer then a human again :).Also enroute between KBJC and KFNL you'll pass over 2V2 (Longmont Vance Brand), a Class G airport. But as it does not start with a "K", it's telling you that there is no wx reporting at that airport, so it should not factor into the equation.Good thread!Bruce.

[Guest christian]

Couple of questions:What is the switch to enable the grid view in FS9.cfg? Is it WeatherGraphDataInDialog=1 and this gives you grey dots all over the place? I'm just interested, because I reverse compiled the weather themes and just want to know if the dimensions relate to each other...Weather themes basically define a 1000x1000km area, with 32x32 grid points.Since I'm a 'scenery guy', I'm really only got into this weather thing quite recently, and since people keep sending me questions abouth the weather engine (after I released my themes doc), I keep having an interest. One of the queries I got was from someone who wanted to possibly write a dynamic weather engine for FS2002. I had the idea that you could possibly write your own weather server, let FS2002 connect to that and feed your own data in. I guess one could do that in FS2004 with setting "WeatherServerAddress=127.0.0.1". Just out of interest, how did you solve that in your program? Just wondering if one could also get FS2004 to get more weather data in, not just at weather stations...Cheers, Christian

[Guest in_04]

Hi Christian,youre right with the WeatherGraphDataInDialog setting. So far I understand the grey dots show the stange(?)/power(?) of the weather or maybe the visibility(?). I'm not shure must check this sometimes :-)The Weather Themes would be transferd in the weather cells, so I guess that they have the same grid. I thought they where small as 10x10km but I guess that youre value is right and each cell is 31.25x31.25 km. So that should be the grid FS9 use for showing clouds. My examinations with weather cells show that they are transferd in the dynamic weather engine, and run there like normal handset or downloaded weather. So I think both use the same data.The idea of having a dynamic engine for FS2k2 with a weather server is ok, but the problem is that the weather downloaded from Microsoft/Jeppesen is compressed and possible scrambeld :-( My first idea for my weather program was, to use the MS data and correct it, or to make a METAR to Jeppessen converter, but nobody knows the format MS use for their download weather.The current way my program, and every other program like ActiveSky and FS Meteo, work, is to download real world METAR files and translate them to something you can use with FSUIPC. FSUIPC is a program where you can read/write several internal FS variables. The new version 3.xx include the possibility to set the cloud/temp/wind/visibility layers for every station FS9 know. So my program set the wx-station one by one with FSUIPC. The process isn't very fast, so currently I limit the update radius to 250 miles. The setting of all 11000 wx-stations of MS would take several minutes.To got more wx-stations in FS9, we could try to change the wx-station data FS9 read. But because the files are copyrighted we should not discuss this here, send me a privat mail for that.Hope that help youByeMarkusPS: Did you find out what the unknown values in youre weather theme doc are?