Help needed with creating a custom weather theme


New member

First time poster here, so if this is placed in the wrong forum I apologize.

I'm trying to create a challenging weather theme for an on-line flight with some friends, but I can't get Active Sky Next to do what I want.

The fictional METAR I'm trying to recreate looks like this.
ENHV 041200Z 19020G35KT 160V220 2SM -FZ SN FEW020 BKN030CU OVC050TCB M2/M5 Q0987

The issues I'm running into, that really matters for the flight are the wind settings. It appears as if ASN won't accept the Gusts and Variable wind directions (in bold in the METAR).
Is there any way to get this into the theme manually, or is that always dependent on using the Synthesize functions, and thus more random?

Also it appears as if the FREEZING part of the SNOW section won't work, but that's of little importance.

Any input on this is most appreciated.
Kind Regars
Mikael Stockfors


Staff member
Hi Mikael,

it works here. Steps:

- Go to ASN Wx Configuration page and select live mode first (to get realistic winds aloft) and after you see "Idle", then go to manual mode.
- Enter ENHV in the station ID (the current metar of ENHV will come up)
- In the "Edit Metar" text box, paste the part of the metar after the zulu time, i.e.: "19020G35KT 160V220 2SM -FZSN FEW020 BKN030CU OVC050TCB M2/M5 Q0987", replacing the current one. It's not important to keep the original zulu time part the same, but it's better to do this (under certain circumstances ASN may consider the metar delayed and use the TAF instead, so best is to have a "current" zulu time. By "current" I mean close to the active time)
- Click once outside the Edit Metar text box. All the winds/temps etc will be updated
- Select an application range and click "Apply to Range"

Now, moving to conditions page (or on the map) and clicking ENHV, the conditions will be updated. So, by directly pasting the metar this is possible. One shortcoming of ASN is that you cannot insert (currently) the gusting part and the winds variability part through the winds table/grid. This has to be done through the metar text box. Depending on feedback this functionality will be added in the future (at the moment it's low priority).

As for the freezing snow part, ASN will recognise this as "-FZSN" and not as "-FZ SN". It has to be one word. Of course the "freezing" part in this case is redundant since the temperatures are below zero, so in the decoding it will be presented as just "-SN", but that makes no difference. In the sim what matters is that ASN will apply icing on the aircraft in this case regardless of the presence of the "FZ" part in the metar.

(well there is a small issue with manual weather and icing, but just by restarting the application and keeping the mode the same, it will be applied appropriately as can be seen in the debug window).

EDIT: I tried the approach and it's very very interesting and demanding. Down to the minimums! Remarks:

1) ASN applied a significant brief downdraft (-1500 ft/min) on attempt to circle to land to RW26, as warned by the chart (not to mention the gusting crosswind). Of course I got here the maximum downdraft setting to 1500 to make this more realistic. The default is 500
2) I took off from ENHV, went around and then attempted the approach. Most of this time (about 20 minutes) the aircraft was exposed to icing (I did the "restart ASN" trick I mentioned). In addition to the pitot heat that froze in just 1 minute (that is an unrealistic "feature" of fsx), during short final the aircraft performance was significantly deteriorated (I avoided any anti-ice in purpose). Icing simulation in fsx and whether it's realistic is a whole new discussion. Suffice to say, that in real life when freezing rain (rain not snow) is present, then it would be extremely dangerous to fly this scenario. In fsx the rate of icing accumulation is too slow. It's there, but too slow.
3) The MDA (according to the first chart I googled for: is 1280' However for ASN to depict fog there has to be a suitable cloud at 1000 feet. If not, ASN inserts one (a "synthed fog" overcast) at 1000' feet. So you may have to descend below the MDA to see the runway. If you want to disable this behavior, then Add the following lines in [Visibility options] section of the file %appdata%\HiFi\ASNFSX\Options\FSXOptions.cfg


Keep in mind that this is suitable only in specialized cases like this one and in general it should be not used or many problems may come up.

4) The clouds are rather squeezed at this latitude (another fsx "thingy") and with all these layers apparent z-order issues were apparent due to yet another fsx bug (fsx determines how to draw the clouds, the draw order, only by checking the lateral distance to the aircraft/camera viewpoint, skipping the vertical distance causing this)
5) You may consider the gusts to be rather "smooth". This is done in purpose to discriminate them from wind shear. This can also be adjusted. If needed just let me know

Now let's go fly!


New member
Thanks for your feedback Kostas.

I'll have to retry it again tonight then, because I must have done something wrong last night.

In my attempts last night I did exactly as you described above and when I pasted in my METAR string in the Edit Metar box I got (if I remember correctly) a white "!" in a red triangle next to the METAR box saying it was an invalid METAR.
And considering the Gusts and Variable wind components weren't available in the settings in Manual Weather I assumed it was those that caused the problem.

Perhaps, as a suggestion, you could in the future add some information in that pop-up with regards to what it is that is invalid in the METAR...

By the way, do I need to have the "Bypass Synthesis" option unchecked for this to work?

Another question just popped up in my mind too...

We fly these sessions as Multi-Player sessions using the built in Multi-Player module in FSX with the weather set on the host computer. How much of these effects will be recreated for the other participants if they don't have ASN active? Will for example the downdrafts you mentioned be recreated by FSX, or are they something that will require ASN to be running?

As long as all of us have ASN installed I'm guessing I could just save a "Weather situation file" and distribute among us, and I think most of us do have the software (I know at least 3 out 5 of us, including me, own it).

As for this being demanding , yes that was my intention all along :devilish:

Although I did start out by trying the Historical Weather option, but failed to find a suitable date with the weather I was looking for...
If the winds were demanding enough the visibility was even worse than this, and if the visibility was fair the winds were just to weak to pose a challenge ;)

If you want to try out the full flight we will be doing in these conditions we will be departing ENKR and then doing Touch and Go's at ENVD, ENSS, ENBS, ENBV, ENMH, ENHV, ENHF, ENAT, ENSR, ENTC, ENAN and ending up at ENSK with a full stop landing (Actually there are two more fictional freeware grass strips in there too but these are all the ones available in default FSX). The plan is to apply this weather globally for this session.

I guess I should be getting back to work now though, and sadly it isn't Flight sim related ;)

Mikael Stockfors


Staff member

the bypass synthesis is not relevant when enabling the weather through the metar (it will always apply synthesis elements like fog clouds in this case). So leave it to whatever you like.

As for sharing it's best to create the weather in ASN, then save the weather and share the .wx file created with the application. Relying on the fsx situation file, is not enough to get the full potential (you will not get visibility restrictions when entering a cloud, downdrafts, turbulence will be different, the rate of wind variability and gusts will be different, you may miss any windshear encounters, icing will be a non issue when flying below a cloud etc etc). So, it will not be an apple to apple comparison. Those with ASN will have a more difficult time in there :)


New member
Hello again Kostas.

I managed to get things sorted earlier in the week, but after testing I eased up on the settings a bit to give us a better chance to actually see something too..

However, when I distributed the saved .wx file to my friends it fails to open on their end. I've double checked with them, and we are on the same version of ASN (SP1B) so I'm kind of stumped on what to do to get this working. I can open the same file on my installation.

One of my friends provided this screenshot of the error message.

My finished .wx file can be found here. Fjords weather.Wx

Any thoughts on this?

Kind regards
Mikael Stockfors


Staff member

certainly a bug (manual weather needs many improvements). Can they try loading the file after downloading historic weather at Nov-5th, 1900Z?