My "tidal basin" cherry tree
I planted what was described as a "tidal-basin" cherry tree about 20 years ago. It blossoms with slightly pink-tinged petals at first, but looks white during most of the bloom. This has happened this year and every other year except last year. Last year the petals were quite pink and remained pink even after they fell to the ground. I took pictures because it was so surprising. I can't find any discussion of why one tree would vary in tinge from one year to the next, but it must have been a change in conditions. Any explanation you could share would be great.
Montgomery County Maryland
The tidal basin planting of cherries includes several varieties of flowering cherry, though some predominate more than others. Yours may be a form of Yoshino Cherry (Prunus x yedoensis), a common hybrid used in the area. As you mention, typically they start out pinkish when budded and first opening, and mature to white before falling.
While we aren't sure as to why your flowers didn't turn white last year, environmental conditions may have played a role. Other plant species are known to have flower color influenced by temperatures, though this does not seem to be mentioned in relation to cherries. In those cases, cooler temperatures can result in weaker "reds" in some species (crepemyrtle is one example) and stronger reds in others (some orchids and roses). While 2019 was warmer than average overall, March was one of the few months where temperatures were below average that year. Last spring's peak bloom (at the tidal basin, at least) was reported to be April 1. Therefore, it might simply be the case that weather influenced the color on your trees.