FSX/P3D. I haven't had time to look into myself just yet but indeed it looks very interesting. Here's the information according to the product page:
What does that actually mean? In principle, FSX/P3D (with replacement textures) is capable of visualizing impressive weather. But the mere injection of unaltered METAR reports into stations provided by FSX/P3D delivers disappointing results. To overcome these shortcomings, FSXWX generates its own weather grid system and enhances the weather with regard to its presentation in FSX/P3D. By this means, unpleasant cloud depictions are avoided and the weather looks more vivid although it might be necessary to slightly relax the accuracy of the weather reports for that.
Another feature of FSXWX is the decoupling of wind injections into FSX/P3D from the rest of the weather by using a unique technique with FSUIPC offsets. Hereby, it is possible to control the wind on a realtime basis with a custom wind module in the background which leads to super smooth wind transitions (lateral and vertical) as well as custom wind gusts, turbulence and variance.
Also noteworthy: FSXWX is specifically designed for complex and 'sensitive' addon jetliners like the PMDG NGX & 777 or Flight Sim Labs A320-X to provide a comprehensive, bug-free and gapless weather from take-off to landing. This includes scaled (but not simply deactivated!) weather effects like turbulences and gusts which I think are essential for the flying experience.
- FREE of charge
- Realistic weather depiction based on METAR reports and GFS data (GRIB format)
- Custom weather grid with more than 65.000 stations
- Worldwide coverage including oceans and unpopulated areas
- Unique direct wind control with realtime updates on the go
- Natural fluctuation of wind speed and direction
- Realistic local weather, including 'educated guess' for CAVOK/NSC/NCD conditions
- Entire raw data is three-dimensionally interpolated to eliminate harsh transitions
- Worldwide true winds aloft and temperatures
- Historic weather for the last 365 days archived and selectable
- Sophisticated injection to minimize disturbances within FSX/P3D due to simconnect
- Cloud depiction enhancements for a better visualization in FSX/P3D, including overcast conditions
- Realistic visibility on surface and aloft including foggy conditions
- Carefully implemented turbulences and wind gusts to harmonize with complex addon aircrafts
- Depiction of vivid weather to make flying in FSX/P3D more immersive than ever
- Easy-to-use and lightweight client interface
It looks like you can try this out now. Thanks to Ross G for the tipoff. More info and downloads via the source link.