As Sandy heads north, weakening as it travels, high pressures along with a ridge progress eastward. The picture below depicts Saturday afternoon at 3 p.m. Temperatures are warming across Indiana with the approach of the ridge, and also some precipitation as a low pressure system moves in.
The precipitation for West Lafayette can be seen as early as 3 p.m. the following day, Sunday, although is at a peak Monday morning at 1 a.m. as depicted in the image below from the GFS. The base of the trough is approaching and colder temperatures are moving in, making the warm weather rather short-lived.