LOS ANGELES (AP) — Forecasters warned Thursday of an onslaught of gusty, dry conditions that will dramatically raise fire danger in large swaths of California as surface high pressure builds into the Pacific Northwest. In Southern California, the National Weather Service predicted a siege of Santa Ana winds with powerful offshore gusts and very low humidity levels beginning Thursday night and lasting through the weekend. "This could be one of the more significant Santa Ana events we've seen in many years," said Eric Boldt, a Weather Service meteorologist.