06Z before fixing

12Z after fixing

The wind direction is now consistent.

Thanks to @tawmdotcom and @Wheats

I'll try contacting MSC and reference this thread as it contains all info needed for debugging the issue (at least I believe so).

MSC AniMet

https://eccc-msc.github.io/msc-animet/?layers=HRDPS.CONTINENTAL_PN%3B0.75%3B0%3B1%3B0%3B1,HRDPS.CONTINENTAL_UU%3B0.75%3B0%3B1%3B0%3B1&extent=-10919169,3542499,-3460008,7081715

I don't know if there is a difference between the HRDPS I see right from MSC and the HRDPS Windy gets but the direction is definitely off, even isobars are much more smoothed out on Windy.

When I load gribs for this forecast step (u-component available here and v-component here) in QGIS, for example, I get same result (+15m/s in v-component and almost zero in u-component):

So I believe we (as windy) are displaying the data correctly. Unless u/v-components are not east/north components, but rotated (since HRDPS is using rotated latlon projection, as stated in the docs). But that would mean that all wind directions are displayed wrong, which doesn't match Your observations.

You seem to be absolutely right. In your example on the sea, the wind angle predicted by HRDPS relative to the isobars is really not plausible and too important. Moreover, this direction is not consistent when compared to other models and to the forecasts you have shown.
The developers should seriously take a look at this issue.

Edit: On the west coast, the HRDPS forecast wind direction seems more consistent when compared to those from ECMWF, GFS and HRRR Alaska. This is strange.

Personally, I don’t see any problem with the wind angle relative to the isobars when using the HRDPS model.
Over the sea, we can generally observe that the wind forms an angle of 15°/20°. Here, over Hudson Bay, the angle is a little larger.
Over land, it is generally 30°/40°, but it increases if the terrain is more rugged.
In the mountains, especially in the high mountains, this angle can reach 90°, as you can verify with other models over the Rockies. This is what we observe in British Columbia.
These changes in angle relative to the isobars are due to increased friction on the earth's surface.