How the FS 2004 Weather Engine Works?

[Guest byoung]

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

[Guest in_04]

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

[Guest in_04]

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

[Guest]

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

[Gridley 257]

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

[Gridley 257]

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

[Guest byoung]

>>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.<

[Guest GabrielR]

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?

[brucek 38]

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.

[Guest DonaldS]

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

[Guest byoung]

Don,You can post links in html with the href=..You have to use html links.One thought...I am loading a flight plan... Could that be overwriting the weather?Prior I delete all the temporary internet files via Internet Explorer.(1) Select the Plane.(2) Load the Flight Plan. Answer yes to move the aircraft to departure location.(3) Real static weather download.(4) Launch FlightIs this correct?Or does FS 9 use the weather that was saved with the flight plan was created??Or is the flight plan independant of the weather? Just a guess... Barry

[Guest DonaldS]

>You can post links in html with the href=..>>You have to use html links.Hi:Yep, I understand that. My question though, was whether I should post the pictures here or over in the AVSIM "picture upload" page with a link to the AVSIM picture upload page, here.Regards,Don S

[Gridley 257]

Post 'em here - mod's will move the thread if it's a problem...

[michal 44]

>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.Markus,I probably agree with you. What I hate most are sudden "jumps" in how the weather looks. This destroys any sense of realism for me. So a "real" weather with discontinuous jumps is no real for me. If FS2004 "dynamics" produce smooth weather changes (haven't tried it yet) then this would be my choice. Michael J.http://www.reality-xp.com/community/nr/rsc/rxp-higher.jpg

[Guest DonaldS]

I posted the pics in AVSIM's Picture Post forum....http://forums.avsim.net/dcboard.php?az=sho..._id=78281&page=Don S