Hi Damian and Jim !I read attentively all the posts regarding the clouds pop-up (or pop-down) transitions, because I experienced that a couple of times, and it cancels all the realism that you can get otherwise with AS2004. I know how much it is difficult to track a bug in a piece of code, so I decided to try to reproduce reliably one such transition in order to give you as much info as possible.The flight is LUBL to LHGD (see flight plan annexed). The airplane is the default King Air 350. The only add-on is FSNav. The weather download is 23 Dec 1200Z. The nearest METAR station from LUBL is LRIA, with the following METAR : LRIA 231130Z 32005MPS 3000 -SN BR BKN007 OVC070 00/00 Q1015 NOSIG 15690293For take-off and first part of climb, no problem : the sky looks overcast with snowfall, with a cumulus layer at low altitude. Up to now, the weather is breathtaking ; then around FL230, all clouds disappear suddenly, a few seconds before the green stripe appears on top of screen with AS2004 weather from LRSV. The whole sky is clear ! LRSV METAR is : LRSV 231130Z 33008MPS 4000 -SN BR SCT004 BKN030 OVC080 M01/M02 Q1015 NOSIG 34591294.What is strange is that Active Radar shows that I should be above a lot of snow (see image). I continued the flight in order to be just above LRSV, and the sky looked still clear (see image). Following the advice of this morning, I tried again with Global Write enabled, and I obtained the same result.I attach : (1) the flight plan, (2) flight image with radar situation, (3) flight image right above LRSV, (4) AS2004 window just after cloud transition, (5) AS2004 options window.The FSUIPC options are the minimum weather default, except for visibility : I checked Random METAR extend, and gradual visibility with standard figures (because I find the unlimited visibility is seldom realistic).As I can reproduce this flight, I can make it again, if you want, trying to collect other infos (like creating a fsuipc.log for the cloud transition).Hope this can help.Alain

Thanks for the detailed report!After switching to Global Writes did you re-start AS?Keep in mind that you need to be within 2 miles of a station to be under the total control of that stations METAR.Keep us up to date!Hope this helps,JimActiveSky Support

Hi, Jim !OK, I started the flight again, after having verified that Global Area Writes was checked (it was !), and pof ! the same abrupt transition occurred at the same time ! I also continued to fly to LRSV (within 2 NM - see image) and the sky was still clear.I observed however, that the TAF message at LRSV was auto generated by AS2004, and the sky was considered as CAVOK. Is this a hint to the anomaly I observe ?Thanks and... hope this can help !Alain

Alain,Try leaving global writes ON and TAF forcasting OFF. Restart AS. See what happens with those changes.J

My second test was already with global writes ON and TAF processing OFF. AS2004 had started in these conditions. My idea behind my previous message is that, even with TAF processing unchecked, AS2004 somehow misinterprets the data to generate TAF messages which do not corrrespond to the METARs. But I do not explain why these data should become integrated in the visual landscape... but maybe is it a hint to a bug ?Alain

Ah. So you're wondering if maybe AS is doing TAF forcasting even though the option is unchecked, and thereby introducing artifacts into the weather.Do you get scrolling messages in the sim on weather updates that AS is creating TAF-generated weather? The times I have seen TAF in action, it will usually append a RMK section to the end of the METAR data (like RMK AS2004 DYNAMIC TAF) or some such thing. That would seem to me to be a fairly strong indication that TAF-forcasting was doing something it should not (assuming you've unchecked this option).

One other thing to check: make sure you have dynamic weather in FS turned off.

OK, I checked dynamic weather, and it is OFF.The TAF message reads as follows : LRSV 231000Z 231812 35012KT CAVOK RMK AUTO GENERATED AS2004What I think is strange is that apparently AS2004 generates a CAVOK situation when the weather at other nearest stations is overcast with fog and snow.But the local METAR, as displayed on the screen, is with snow, fog and overcast (see attachment #4 in my first post)Alain

On the surface, it does seem odd that you would go from Fog/Snow to CAVOK conditions. Although, it's hard to see without seeing the weather at nearby reporting stations. If the weather to the west was rapidly clear, then a cloudless isn't completely out of the question. I've seen it happen in real life. A brisk moving front with a strong cold high pressure center filtering in dry cold air behind it.J

I have noticed that as soon as i get a AUTO GENERATED AS2004 appear in the Active METER Report I`m getting pop up clouds - Its fairly smooth clouds until this happens

Hi, J and BinzyFirst, I want to say that I

I do agree with all of your explanations Asquel.I'will try to notice the Auto Gen BinzyI've done the same test but nothing change, no overcast.I've posted a message "No solution for overcast weather" with somme screen shots and i have sent all the files to Damian also by mail.I hope that this can help Damian and Jim...Jean-Michel

Hi Alain and J - Just tried something else - I usually fly live - but just started out on a flight from EHAM - CYVR . Started the flight 3 hours behind real time and had the smoothest cloud transitions to date until this BIHN 021717Z 00000KT 9999 BKN035 BKN050 M08/// Q1014 88750095 RMK AUTO GENERATED AS2004Alas pop up clouds Regards Rob