The rise and fall of signal strength in each "link" - the path from one mast to another - provides an average measure of how much rain there is between them.
What we have said all along is that it sends the wrong signal and it would be a mistake to directly link, tie, or hold hostage one to the other because of the absolute necessity of raising the debt ceiling.
If you happen to come back into a 4G area (signal level above the 3G value), it switches modes again taking another 30 seconds to establish an active link.