An Unknown Tree Grows in Brooklyn

My friend of 50 years, who lives in Brooklyn, has given me permission to use the "A ____ grows in Brooklyn" meme one more time before she clobbers me.  (oops, too late.) 

As a native of New York City, and someone who loves the world of flowers and gardening, I always love to point out that there are indeed green things growing in New York City, and trees (and other things) grow in all the five boroughs, including my father's native borough of Brooklyn.

My friend is more knowledgeable about plants than I am but she wasn't able to find the identity of this street tree growing in a Brooklyn neighborhood.  I saw the same tree last year in Binghamton, New York (where I work) and couldn't get an ID on it, either.  It is not a Japanese lilac but those white flowers smell so sweet.  It blooms too early for a Japanese lilac.  I don't think it is a linden, but we are fresh out of ideas. 

Does anyone know what this is?

I do know this is a beautiful flowering cherry.

I think the same kind of tree but in a different light.

This tree on Ocean Parkway isn't blooming but it is coming out with pale yellow leaves - perhaps some kind of ash?

And, more flowering trees along Ocean Parkway.

When I see the late snow impacting various areas in the Western United States (including Missouri and Colorado), my heart sinks.  I hope spring comes to them, soon.

Has the weather been unusual for you this spring?