'Explore' -> 'Catalogs'
To check inventory without creating an order, hover over 'Explore' and select 'Catalogs'.
This will open to a list of active catalogs. Simply click on the catalog (or subcategory) you want to view and that catalog will open. You can view product availability by clicking on a style name, and then by selecting 'Availability' from the menu. This will produce an availability table that shows both current and future availability.
You can search for products by clicking on the filter button on the bottom left corner of the screen. Enter a style number, name, or color into the keyword search and that product(s) will appear.