Roof & Ceiling Load Watch (Snow/Water Ponding)

Wet snow and ponded water sit on the roof as a heavy, signal-soaking layer that deepens the echoes from the deck. At the same time, the weight physically bows the deck downward, and the ceiling echoes creep along with it. Two independent signs of one growing load, read from safely underneath.

In the physics: Two coupled observables: (1) accumulated water/snow is a dielectric layer on the roof deck — paths reflecting off or penetrating the deck acquire extra delay and attenuation scaling with water-equivalent depth (wet snow is strongly lossy at 2.4/5 GHz); (2) load physically deflects the deck, migrating the ceiling-reflection tap delay (mm-scale, integrable) and lowering its vibration modal frequency.