Alps: one warm day left before Friday's rain

The Alps get one more warm day before the weekend breaks. Chamonix peaks near 29 degrees on Thursday, then Friday's front drops highs back to 21 and brings roughly 14mm of rain. Higher up the swing is sharper. Zermatt at 1,600 metres falls from 24 to 17 degrees in a single day. Pack the shell now. A bright Thursday morning tells you nothing about Friday's ridgeline.