From this extended weather forecast I would be looking at the potential for a rain event in the California/Arizona area..... although a bit of a haul, monsoon boating over labor day could be awesome:
"LONG RANGE FORECAST DISCUSSION
-25 to 30 August, 2013 - Sunday through Wednesday (25th - 28th) We expect increased and plentiful thunderstorms plus showers across the area as the flow aloft is southwest/ south, and tapping into some subtropical moisture due to weaker high pressure ridging aloft and centered to the southeast, plus low pressure across the northwest US. In addition, we may see a strong tropical storm (or hurricane) cross Baja CA, and send much increased moisture into the area as it cycles across the California and Arizona deserts and then funnels in. This pattern is expected to continue directing moisture in this way, for more clouds and less sun overall. Around this time, some snow is possible in the Washington Cascades, probably well above 7,000 feet, as stronger low pressure pushes into the northwest US with some unseasonably cold air. We will be watching. CM"