Thursday, July 16, 2015
Our weather for later this weekend will be impacted by the evolution of two anomalous storms; an unseasonably strong and cold storm over the northern Rockies and hurricane Dolores presently located off the southern tip of the Baja peninsula.
The previous persistent monsoonal plume of moisture from the south has been severed by westerly flow ahead of the approaching storm to our north. Some drier air will move over the area in this westerly flow and lead to a decreased, but not insignificant chance of afternoon storms for Friday and Saturday.
The northern Rockies storm will shear as it drops southward tomorrow, leaving some energy in northern California and keeping most of its energy to our north and then east. Some cool air filtering into the region from the passing storm will reinforce our seasonably cool summer weather for the weekend.
There is a fair bit of model uncertainty as to how the energy left behind in northern California will progress. Current models eject some energy westward on Saturday, with this energy tapping some moisture from Dolores, but it is not clear whether this moisture will move far enough north to affect our area for Sunday.
Even though it appears remaining energy over northern California will further interact with the remains of Dolores, the moisture may stay south of us as some more dry air moves over our area in westerly flow. By around midweek, another strong storm will approach the Pacific coast and will back our winds to the southwest, allowing the monsoonal moisture tap to reestablish itself over our area.