Thanks to the magic of the Internet Protocol, we have a NOC equipped with Doppler Radar:

That photo is right from one of the big plasma screens in our Network Operations Center. It clearly shows the rain squall tracking towards our roof construction, so we inform the crews up there that it is coming. They cover up the in-progress work with tarps and erect their tent over the one they are working on.

During the above conference the roofers vote to keep going, while the metal workers decide to grab lunch, since they have to wait for the rain to stop. Three holes down, one to go, as soon as this squall goes somewhere else.