Hail Damage During the Monsoon rains in the southwest there can be Hail that falls along with the rain, that is driven by heavy winds.  Winds can reach 45 to 90 MPH or more, and the hail can range from pea-size to grapefruit-size.  Add to this that much of the BorderTransportationSystem traffic will be traveling between 150 and 250 MPH, the damage to stations, entry/exits, signals, and vehicles can be extensive. There is not much that a transportation system can do to protect the users of the system from severe weather, including blowing debris and hail.  There are national weather service detectors and websites that can forewarn of a pending or on-going event, and the information can be used to 'shut-down' segments of the system until the threat subsides. Index of ... April Showers (and Thunderstorms) along the U.S.A. / Mexico Border Dual-polarized (dual-pol) radar technology Interactive Hail Maps are the finest radar hail swath maps Hail - Wikipedia descriptions Hail Detection