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brucek

How the FS 2004 Weather Engine Works?

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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

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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.

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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

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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

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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

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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]

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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.

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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

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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

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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

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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

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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!

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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

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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.

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Markus,When I load the real weather, the briefing says Clear Visibility 50 miles.. Then why am I seeing low clouds.Also the mysterious fog bank is a problem.Yesterday I could see Catalina Island from Long Beach with no weather obstructions or clouds in the flight path, so why did I hit a fog bank? Also near Long Beach I was seeing lightning...The authors of FS Mateo and Active Sky have a big challenge to get the weather into and update the engine properly. It is more complex than FS 2002..Barry

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Hi Barri,I try to give some answers:>When I load the real weather, the briefing says Clear>Visibility 50 miles.. Then why am I seeing low clouds.The METAR reports for Us give only visibility of 10 miles max., this means that at least you could see 10 miles but maybe more. So if youre weather program make 50 miles out of the 10 it is a function of the weather program. Also the visibility means horizontal visibility, so you could have 11 miles horizontal visibility with clouds at 2000 feet.>Also the mysterious fog bank is a problem.Have you examined the stations along the flight path? Look if there is one station with lower visibility. The visibility in FS2k4 is always the visibility of the nearest station, NO averaging between the stations.>Yesterday I could see Catalina Island from Long Beach with no>weather obstructions or clouds in the flight path, so why did>I hit a fog bank? Also near Long Beach I was seeing>lightning...Did you have the UTC time, or the METAR data? Maybe there is a bad station in the flight path. In another thread someone show that KSCD (MCChord AFB) show 7 miles visibility all the time.>The authors of FS Mateo and Active Sky have a big challenge to>get the weather into and update the engine properly. It is>more complex than FS 2002..Yes the engine is more complex, but better than ever. The local weather for clouds etc. is great. The dynamic weather generate intresting and mathematical correct clouds. But FS2k4 is no weather generator for real world weather. The simulation of real world weather would bring youre PC to it knees.The conclusion is -> If you whant always real weather DON'T use the dynamic engine of FS2k4. If you whant intresting and variable weather which is "as real as it get", download a weather snapshot and let the dynamics make the rest.I prefer the second one, the real world is boring.ByeMarkus

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Hi Dick,>The bottom line is disable dynamic weather.I prefer the dynamic weather is on, but I download a snapshot of the "real" weather and let the FS2k4 engine do the rest. This means the weather outside my windows isn't the one I have on FS2k4. But I love to fly in the past, with previously downloaded weather. Yesterday I take a nice flight with the weather data from 2002/12/24 08:00 UTC. All weather changes after 08:00 UTC where generated by FS2k4 and look very "real", but it wasn't real weather.>Maybe you could place your dynamic setting suggestion in the>TIPS section so it does not become lost.Maybe, but I have a question to you:Did you prefer the "real" weather? Didn't you like to fly in the weather of yesterday or last year? I like the possibilities of flying in different seasons and on different days and times.ByeMarkus

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Hi Markus,is there any chance of releasing your already existing weather program for FS2002?Thanks,Claudius

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I agree with markus - I usually fly with dynamic weather on mild change rate. I find it adds some variability that updating every 15' doesn't (especially since most reporting stations don't update but once an hour).One other thing I've found useful: www.bearsoft.de has a weatherget program. This utility downloads the weather from MS/Jepp and stores it as a file on your PC. You can add comments about the weather files that have been stored. I download several cycles from MS and check them out for "reality". The ones that match, I keep, the others I delete. I then load one of those in as the snapshot and fly with mild dynamic change. Love it. A happy medium until the new utilty from ActiveSky/SimWidgets comes along (or maybe a new freeware?)...sg

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Another bit of info, my intepretation on what is going on here:1.) If you have dynamic weather enabled, the WX engine takes data such as dew point and temperatures and generates a trend. This can (and frequently does, maybe too frequently) cause scattered clouds to form rapidly.2.) The "fog bank" is a METAR reporting low visibility. Visibility is not displayed on the screen at distant reporting stations the way that clouds are so you will not see it between here and catalina. As you transition into the range of a new station which is reporting low visibility, FS suddenly changes visibility. 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 have a cheesy workaround for that problem. Pressing -W opens a second window with a nearby AI aircraft in the view. It turns out that FS is not capable of tracking multiple visibilities, so the visibility range that you see out your glass becomes that of the AI plane. I resize the AI window to miniscule, and drag it to an unobtrusive spot on the screen until I transit the anomalous visibility station, then close the window. It seems that only visibility is affected in this way. Pressure, cloud cover, winds do not seem to be changed. It is sometimes necessary to press ctrl-w a few times to find an AI plane outside of the poor visibility area. Some would call it cheating. I don't.Best,sg

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>>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.<

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It looks that some of the features of previous versions have been carried over FS9, However the enhancements are worth the change.For the programer that is developing the weather add on, which rate of change do you consider will correlate more with the "speed" in the changes in the meteorological conditions?

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Hi Markus,Here in the US, METARs are obtained from any airport which has a designation Kxyz. This includes all of the Class D, C and B airports (where there are towers and even meteorological staff, and where the visibility can be actually stated by RVR or some other means).It also includes all of the airports where Class E airspace extends to the surface, and in addition some which only have Class G at the surface. The airports in these last 2 categories far outnumber those in the Class D, C and B categories combined, and have the local weather determined automatically by an ASOS or AWOS automated system. That means that there's not a human involved. These stations report visibility up to 10sm. At 10 sm and beyond, there is no further discrimination. Even 70 sm would be reported as 10sm. (Here in Colorado we often have 70sm visibility).Therefore, FS will import this data and create a 10sm visibility barrier. This will be punctuated by larger visibilities only where a Class D, C or B airport is the one being accessed for wx.Bruce.

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I have prepared a little "Here's my wx problem in pictures".It is a flight from Goodland, Kansas to McCook, Nebraska in the FS 2004 DC-3.Eight pictures showing what happened regarding the cloud build up on a METAR reported Clear day. I have uploaded the pictures to a web server. Can I post the URL with the pictures here? (since it is related to this thread) or should I put it on the AVSIM Picture Post forum?Thanks,Don S

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