The different charts should converge as you get nearer the present time, sure. I don’t think they converge as much as one might expect though.
I see. We’re discussing the forecast (and differences among providers) not eg two charts that show prevailing conditions. Are there differences among the latter as well? Or do they start resembling each other the closer to the actual date and time they are?
We clearly have wires crossed
This chart is prepared 120hrs ahead (t+120)
If you download this chart tomorrow (also for 1200 20/10) it will say t+96 and it will be more accurate.
As discussed here, a lot of free wx sites present these charts but older versions.
Shouldn’t it be based on the time these conditions prevail? Why would it matter when it was prepared (seriously curious)?
Sure, but it could have been prepared at t minus 24hrs, t minus 36hrs etc.
The Austrian one has a date and time stamp.
The corresponding UKMO MSLP
What I don’t know is how old the Austro one is. The above one is current (“analysis”) since it is past 1200 UTC when I am typing this.
I wouldn’t say they are similar.
Looking at the radar
I’d say the UKMO chart is much more accurate because it shows the troughs which give rise to the TSRAs which you see on the radar, and the sferics
https://www.austrocontrol.at/flugwetter/products/zamg/BK_BodAna_Sat_2010161200.png?mtime=1602851966
https://www.austrocontrol.at/flugwetter/products/zamg/BK_BodAna_Sat_2010161200.png?mtime=1602851966
Throwing this one into the ring.. from Austrocontrol (free, btw).
At least the same family from the same provider (DWD). They run at least two “ICON” models:
Is “ICON” on the DWD charts
the same wx model as “ICON” on windy.com