How the FS 2004 Weather Engine Works?

[Guest byoung]

Can somebody give me an idea how the weather is created in FS 2004? I know it supposedly more realistic than FS 2002.But it seems when I am at an airport and look at the Metar, and then look at the cloud formations, they seem strange.Can someone give me an overview of how the weather engine works in terms of how and when it loads the weather and its source? When I look at the weather map after loading the weather updates every 15 minutes option, it has different reporting stations. If you mouse over the reporting stations it tells you the winds, etc. If you are within a certain distance from the reporting station, does FS 2004 take the weather calues and populate the weather?I was flying from KLGB to Catalina KAVX and the weather at KLGB reported Clear and 50 miles visibility, and the Automated Weather at KAVX reported Clear and 20 miles visibility. I saw scattered clouds around the island. The flight path to the KAVX was clear. I am flying along dumb and happy, and wham! In a fog bank, no sign of haze build up, just burried in a cloud or fog. Would like to find out how the FS 2004 weather engine works, since it really impacts VFR flying..Thanks!Barry

[Guest wkzzo]

Barry ,I had the same thing happen yesterday, downloaded static real weather(one time download), flying from KRNT to port hardy BC ,Reporting 20 miles vis or greater, a few clouds @ 16500k. At about 8500k a complete white out that lasted till 10500k. Not sure If thats its way of showing haze or not. Did not have it on the descent though. I have my weather rate of change set at medium.

[Guest byoung]

Thanks Wallace,Yes, I don't really understand how FS 2004 is interpreting weather.I understand that some guru wrote the weather engine, but does it really represent the actual weather, or is it randomly generating weather as you fly along? Should you set your weather generation slider all the way off to simulate actual weather?Again, I am just trying to understand how it works and where the engine gets it weather data and how it generates it based on the weather generation slider.Hopefully others will repond.Barry

[Guest DonaldS]

It happens to me all the time with FS 2004. Very annoying.I am not going to split hairs about what the local weather reporting station reports on METAR as far as 10 miles visiblility or 50 miles visibility or whatever - and how that is interpreted by FS 2004.I do know though, that I went out to the local airport yesterday, a clear, no clouds kind of day, and spoke with a couple of pilots I know, asking them if they'd experienced any kind of "white out" or whatever, when the approached the airport that day. Their replies were "Of course not. There is not a cloud in the sky". I even did some screen grabs of Internet satellite photos of my area showing NO clouds. None.Funny, I had flown the area in FS 2004 an hour or so before (yes, the skys were still cloudless in the real world) and hit the wall of gray and stayed in the gray until I landed. Which required ILS, I might add, because I could not see the runway.It seems that when I download Real Weather, static, FS displays a reasonable resemblence to what the real world weather is. But after about 10 minutes or so, FS can't stand it the fact that there are no clouds an starts popping in clouds. And very unrealistic clouds at that. i.e. clouds springing out of the ground.I know MS is proud of the FS 2004 clouds, and they should be, because they are; for the most part, excellent. But when a day is cloudless there are no clouds. None. The End.As Bob Dylan[?] said, "It doesn't take a weatherman to see which way the winds are blowing" and I agree. (Maybe it was Jerry Rubin who said that) I will take that one step further, "It doesn't take a Meteorologist to know when it is cloudy and when it is not"I have a several hundred hours as a "real world" private pilot, SEL and these FS 2004 clouds just ain't gettin' it in my book.Regards,Don S

[Guest byoung]

Excellent Don,Agree, I just don't think it is realistic. At least with FS Meteo and Active Sky, the global weather kind of resembled what was going on as you were flying. I think the FS 2004 wether engine is going to drive these add-on weather developers crazy, because of all the complexity MS has interjected in the weather engine.Hope others will post, not only the problems, but maybe slider settings etc... And / or solutions in general. I would like to hear from meterological gurus as well.When I departed Catalina, and started heading back to Long Beach, I hit a fog bank for about 10-15 minutes.. Then when I started to descend it suddenly disappeared and kind of went hazy. But as I made my turn on to the ILS Runway 30, BTW I've flown out of that airport for a few years and everytime I downloaded with weather, I ALWAYS got runway 30 as the active, and was about 1100 ft, boom! clearer skys. Maybe it was because I was in the 10 mile radius of the KLGB. And maybe the algorythm, is that if you are not within 10 miles of the reporting station, it generates random weather based on some weather formula. I think it should take the closest readings and interpret that somehow. If the weather was like this in real life, VFR flying would be hazardous. I was really sweating it when I hit the fog back and I had to land at KAVX. One day in real life it happened to me and I had to turn back and land at KLGB. Just cloud cover, NEVER have I hit this wall of fog. Maybe it has something to do with the weather generation...Great post, hope more people share experiences..Barry

[Guest Fortress]

Yes, agree that it's odd. Was using RW Wx today (from within FS) but for some reason decided to switch to FSMeteo whilst en-route. Totally different!Cheers,Paulhttp://www.strontiumdog.plus.com/sbird.jpgOfficially licenced by British Airways plc for use of name and logo[p]AMD XP2800+ Barton, Gigabyte GA-7NNXP nForce2, 1Gig Crucial PC3200 DDR 400MHz, Gainward 128 MB GF4-4200, SB Audigy, 3 x WD Caviar SE[/p]

[Guest wathomas777]

If your dynamic setting is set to medium or any value other than none, the weather engine immediately begins to start a run routine based on the METAR data and creates it's own weather based on the Real Weather download.This is why if you are using the 15 minute updates, you are advised to bring dynamic to slow or off so that the weather doesn't begin to change on you between updates.If you want "REAL" weather conditions, either do the "every 15 minute options" or take regular snapshots of weather while in route and keep the dynamic weather off.If you want "changing" weather, use the Real Weather static as a starting point and let the WX program begin it's subroutines from there.

[Guest byoung]

Then what you are saying is that if you want Real Weather, turn Dynamic Weather off.. And then use the update every 15 minutes weather option.But I would be curious to know how the weather is derived from Metar. Does it take the closest station and then use that weather for a certain distance..Is there documentation somewhere on the FS 2004 Weather weather?Or am I over-complicating things a bit.Barry

[Todd Nicholson 0]

This is explained in the weather section of the FS9 Learning Center.-Todd

[Chris Willis 8]

Hi, This can cause another type of problems to others:Real world weather seems to be giving some strange weather in FS2004. Heres why and how to fix it (straight from Microsoft website) : Flight Simulator: Real-World Weather Is Not Accurate in the Game Microsoft Flight Simulator 2004

[Guest byoung]

Chris,Followed your instructions... Still get the mysterious fog bank.And the weather still doesn't seem correct based on the reporting stations around.Barry

[Guest DonaldS]

Yep, I just followed Chris's suggestions as well and it didn't work for me either. At any rate I deleted all the Temporary Internet files and did the rest of the drill as described but the "instant cloud bank" still occurs. I use (after clearing the weather) Real Weather Static (not the 15 minute deal) but I usually end up going back to >World >Weather and using the User configured weather, trying to match known wx data.But, thanks anyway Chris, for your suggestions. I have often solved FS problems by using your excellent directions and tips.Regards,Don SPentium 4 - 2.8Ghz1024MB SDRAM128MB ATI Radeon 9800G PRO160GB HarddriveWindows XP Home

[Guest in_04]

First I'm a programmer and former real world pilot who made his own weather program for FS2k2 and now bringing this to FS2k4.So I spent several houres examining the weather engines from FS2k2 and FS2k4. Here are my current point of view:1. The FS2k4 weather engine use a good algorithm to determine the wind, temperature and pressure for the weather around youre aircraft out of the weather settings of the FS2k4 stations.2. The visibility is NOT averaged or computed for the different stations. It is the visibility of the nearest station around you! This could explain the visibility drops you described. If you fly along youre path and come close to a station with reduced visibility, let say 2 miles, the visibility drop instantly to this setting until you come close to a station which has better visibility settings :-(Often the visibility of FS2k4 stations is set from ground level to 15000 feet, so it strike you at unrealistic altitutes. There are currently only several workarounds: a.Use a "good" weather program, best is mine but it isn't released, so you must wait until I do so or take a look at FS Meteo or Active Sky. I didn't have one of these so I couldn't say for sure that they fix the problem but I think they should do. b. Buy FSUIPC, it has a visibility options. c. Examine the stations around youre flight path, for stations with "wrong" visibility settings.3. The FS downloaded weather has several failures inside. One I have found is that some stations have every time a visibility of 10 miles even if the real METAR report show higher visibility (it is a station in Germany where the visibility is often give as km (like 50KM)). Also a visibility setting from ground to 15000 feet isn't realistic for visibilitys under 10 miles. Often there is only haze in lower altitude and not constantly up to 15000 feet.4. The dynamic weather generation engine does a good job, but it do it to fast. I think you could use the lowest setting or change the speed factors in the CFG file. The generation of clouds is done on real world meterological data and is ok. A problem with such generation engine is that they normaly not have all data to match the rela world. So they use statistic data and probabilities to generate clouds. But the real world is not so easy, sometime the temp/huminity and other values are right, but no clouds are forming. Sometimes the values are "wrong" and there are clouds. The problem with the FS2k4 engine, like every engine which could only use ground based meteor data, is that they know nothing about the huminity/temp and other factors (like solar strength etc.). Theyonly could guess on a mathematical model, and I sayed it before the FS2k4 model is not bad.5. The Jeppesen metar data are stripped down real world data.6. With ground observation data (METAR) you could not make a forecast and you have only some pieces out of a large picture, so you could not show the real picture.7. In FS2k4 there are to few clouds and other settings (like more than one visibility layer) to make the weather right.8. FS2k4 use weather cells, aproximilate 10x10 km wide to generate the dynamic weather. Everithing in such a cell would be computed out of the stations around. You can switch on a visual view of the cells in the cfg file. The weather picture is build out of these cells, but the cells are only generated if at least one weather stations is in the cell. So no cells over the ocean and some aras, like Australia, has only very few cells.So that some of the currently know features of FS2k4 weather.My suggestion for "real world" weather is: (++ means best, o means average, -- means bad)++ Get a METAR based weather program with Internet update function and disable dynamic weather So you get the real world weather at the METAR time, the time until the next report receive (normally ONE hour), the weather you have is not realo Use FS2k4 build in weather with 15 minutes update, without dynamic weather -- Use dynamic METAR weather with FS2k4 build in dynamic weather engine on higher settings. This would give you popping clouds and constantly changes in the weather which doesen't match the realityMy personal suggestions for "real world" weather is:++ Download the METAR weather with my program :-), NO Internet updates and let the FS2k4 weather engine make some dynamics with it. This isn't the real "real world", but it is close to a fictional "real world" where the weather at the downloaded METAR time is this and one hour later it has changed to something different.o Use the build in FS2k4 weather engine, take a static Internet download and let the weather engine do the resto Use a METAR based program, which download the whole world METAR weather and use the dynamic weather engineWow, that was much to say and I hope you understand my english (it isn't my first language)ByeMarkusPS: If you are intrested in my weather program, stay tuned and wait for the anouncement. The only thing I would say now is:It will be Freeware!

[siggy 154]

Hi Markus,You are right I believe why the visibility jumps around in FS.I wish they would fix this. It shouldn't be too difficult inside FS to derive the average visibility from the reporting stations nearby and continuously work out an average. I thought that these 'weather jumps' that we had in FS2002 are over in FS2004.Cheers,Siggy

[nudata 10]

Good English and understandable. The bottom line is disable dynamic weather.I was going to say that I did not understand anything except "Freeware!"Dick KLBEMaybe you could place your dynamic setting suggestion in the TIPS section so it does not become lost.