by Wildhorse » Tue Sep 22, 2015 2:41 pm
According to the LA Times article linked above, the chance of rain was 40%, according to the NWS forecast, and the flash flood risk was moderate. That was the forecast they had access to in the morning for the afternoon. Perhaps they did not check that forecast, but another one that was different.
At the time they phoned a relative to ask for a weather forecast update, the NWS forecast had been raised to 50% and the flash flood risk was "probable." According to the LA Times, the relative sad there was a "chance of rain." We don't know which forecast the relative viewed, or exactly what was said. This exchange implies caution on the part of the canyoneers, but possibly bad information was transmitted.
No one will ever know what happened.
The LA Times article also notes that very large numbers of people now travel through these canyons. Skyline, S Korea, Katahdin, Zion: all are seeing more adventure lovers, more deaths, more rescues, and more damage to the land. It is a flash flood of people.
Over the last week, the City of San Diego installed new timbers to patch up part Cowles Mountain damaged by hikers, trail users, exercisers, or whatever they may be called. The timbers look like bulkheads - blackened with creosote. They are bulkheads, really, installed to protect the land from the powerful waves of humans that beat against the mountain.