Not the dev, but these are probably hexagonal bins that were computed in spherical/conic space (e.g the Albers Equal Area or Lambert Conformal projections [0],

Not the dev, but these are probably hexagonal bins that were computed in spherical/conic space (e.g the Albers Equal Area or Lambert Conformal projections [0], which happen to also be the projections that NOAA distributes a lot of their data in) and projected to Web Mercator (which is the web maps projection). Usually when you do that you get bendy things. [0]: https://psl.noaa.gov/data/narr/format.html https://psl.noaa.gov/data/narr/format.html