Yes, the El Nino does change the persistent high pressure observed in the southwest over the last several years. As illustrated in the last figure of Emily's blog post a week or two ago, http://www.climate.gov/news-features/blogs/enso/june-el-ni%C3%B1o-updat…, during El Nino the Pacific jet stream usually is extended so as to encroach on the southwestern US, bringing its storm track with it. This means that even if there is still a tendency toward a high pressure ridge over the western US, there could be repeated interruptions as low pressure systems undercut the ridge on its southern side over southern California and Arizona. So there is hope for some relief from the drought, especially south of 35 N latitude, and if it turns out to be a very strong event, the better rainfall (especially in late winter, Jan-Mar) could benefit central or even northern California as well.