@HB427112 @N6722C @HalberQuacky
I believe the question Walter is struggling with here is, “why is the reported weather in the sim so different from what is actually being generated in the sim?”
When approaching an airport, details about the weather from ATIS does not always agree with what is out the window or even what you get from tower when clearance has been issued.
I have had instances where the ATIS wind is very different from the wind provided by ATC. re: ATIS says wind is 260 at 20, landing and departing runway 27. I get cleared by ATC and they tell me the wind is 195 at 30. This happens regularly IRL.
ATIS is a recording of the last observed weather at the airport and depending on when you are approaching it could be nearly an hour old. Pay close attention when you get ATIS and check the time stamp.
When tower gives you wind and altimeter, they are looking at the live display in front of them. If you have ever golfed you would be very familiar with standing on the tee box and watching your ball sail off target because just as you started your backswing there was a significant wind shift both in intensity and direction.
Short Story
20 miles out, at the end of scenic flight in a 172 around our local countryside, I called FS (no ATIS available) and indicated I was 20 north east inbound fullstop.
FS: “IIU, YDQ Radio, altimeter 29.95, wind 275 at 10 gusting to 20.”
ME: “YDQ Radio, IIU will be joining left base runway 27.”
10 miles out…
FS: “IIU, YDQ Radio, be advised altimeter 29.93, wind 235 variable to 210 at 25 gusting to 40.”
5 miles out…
FS: “IIU, YDQ Radio, altimeter now 29.90, wind 215 variable to 175 at 35 gusting 50.”
After second go around and the snow squall intensified, bring visibility down to marginal, flight services called again as I was climbing back to the circuit…
FS: "IIU, YDQ, wind is now 165 variable 185 at 50 gusting to 70. Your intentions?
ME: “YDQ, IIU will be left base for the grass beside taxiway Alpha.”
Turning directly into the wind we did a very shortfield landing.
I could hardly see as we taxied to parking and very nearly lost control a couple of times due to wind gusts. By the time we got shut down and tied down, we had clear skies, sunshine and a light breeze. No-one expected the sudden squall but being in close proximity to the mountains they are not uncommon. Had we known it was only going to last for 20-30 minutes I would have just gone and tooled about until it blew over but it could just as easily been the start of and expected cold front and may have settled in for the rest of the day.
Point of the story.
Localized weather, depending on your location can change radically in very short order. MSFS is using weather reports that may be hours old to augment the forecast weather model. If your ATIS is from more than 30 minutes ago, local conditions my differ. If there is a significant change in the weather then a SPECI is released in between scheduled updates, but as you can see above, this all happened so quickly that even if we had an ATIS service, in the time it would take to record the SPECI the conditions would have been returning to the sunny and calm.
The current MSFS weather is still a bit of a Frankenstein’s monster. We will hopefully begin to see a bit better consistency as we approach our destination and go from forecast conditions to reported as they attempt to tweak and blend, but remember that even in real life, reported weather is only accurate at the time it is observed. By the time it is reported it is now historical weather. The only accurate weather you can rely on is that provided by the controller/FSS as you turn final.