Very preliminary right now with not very many details, but it appears to be a
condo/hotel tower at
43 stories tall, making it one of the tallest buildings in Phoenix.
The Art Deco building immediately to the right of the tower is the 1931 Valley National Bank building which is currently being renovated into a boutique hotel by the same developer who wants to put up the Momentum tower. The same developer is also currently topping out a 34 story condo tower, 44 Monroe, just down the street from this project. Bottom line, they definitely already have a strong presence in Phoenix's downtown.
I love the architecture of this one, something new and striking for Phoenix.