Freeze-Lock: Set temp to 5°F, no rain. Notice temp_decay = 0.00. SDI barely moves—only the 0.03/hr heat loss applies.
Spring south-facing: South orientation, March, 35°F. The orientation_multiplier (1.65) and season_multiplier (1.35) stack to create steep melt.
Rain-on-snow: Set rain to 0.20 in/hr at 40°F. The temp_decay jumps to 2.0 (rain column) and rain_multiplier adds ~5%. Watch the SDI plummet.
Shaded roof: Set decay_multiplier to 0.5 (user observed more snow than estimated). Everything decays at half speed.