Brief description of the issue:
The winds observed aloft seem to never match other forecast models. In part, this happens significantly over mountainous terrain, and seems to incorrectly calculate ambient conditions for winds and temperatures based on aircraft AGL altitude rather than pressure altitude (i.e., what the models represent).
Provide Screenshot(s)/video(s) of the issue encountered:
One example: live weather at 2021-01-12 0042z, taken at N41.683, W107.904 at a pressure altitude of 40,000’:
- ECMWF: 340 deg @ 43 knots, temp -67C
- GFS: 340 deg @ 39 knots, temp -66C
- NAM: 350 deg @ 37 knots, temp -67C
(note: all of the above are within reasonable accuracy)
Sim: ~045 deg @ 57 knots, temp -55C:
(grossly different)
Comparison:
- ECMWF:
- GFS:
- NAM:
NAM comes the closest to possibly representing the correct wind, and that’s at ~300hPa pressure altitude (roughly 30,000, which is 10,000’ off from my pressure altitude of 40,000’ in this example). Incidentally, the ground elevation at this location where this example was taken in 6,796’. This may be related, as I typically observe that winds and temperatures aloft are incredibly incorrect and wildly variable when flying over mountainous terrain.
Similarly with temperature, the -55C observed occurs in the aforementioned forecast models at a pressure altitude of ~250hPa (roughly 34,000’)
Detail steps to reproduce the issue encountered:
Fly a flight over a mountain range (e.g., Alps, Himalayas, parts of Ethiopia, Sudan, etc.). Note:
- Pressure altitude
- Ground elevation at your position
- Winds aloft where you are
- Temps aloft where you are
- Winds aloft data for each forecast model at your position and all altitudes
- Temps aloft data for each forecast model at your position and all altitudes