Create spread curve looking at dates relative to calendar year

We're an engineering firm in a cold climate - so our work has a strong cyclical pattern. Low volume is in the winter when ground is frozen; high volume is in the summer when construction can proceed.

In 12.1.3's Project Management module, we have very basic time-phased budgeting and forecasting implemented - our implementer set us up with spread curve Even. We're looking to change this now to default more accurate data without forcing project managers to manually spread all budget numbers over relevant periods.

For example, if a project began in January 2017 and ended in December 2017 - the seeded bell curve would be perfect.