After rain the empty riverbeds can fill up within minutes. Dry wadis turn into rushing torrents that can wash cars away. This photo shows me biking in the Sde Boker area a few hours after rain. The water catchment area where I live is small, so the water quickly runs away. At Nahal Tzin, only five minutes from Sde Boker, the water takes several hours to drain away because it is part of a different catchment area. The Nahal Tzin wadi drains a much larger area, the Mitzpe Ramon hills , which are a 30 minute drive south of where I live.
In 2010, the Dead Sea rose 10 cm because of the flash floods. I was driving home from Mitzpe Ramon at the time of the flooding. The river bed crosses the road in three places. In minutes the road was under rushing water. I was one of the last people through before the police closed the road to traffic because of the danger of being washed away.
If the forecast is for rain in the desert, make sure you’re on high ground.