The low-level circulation that once was Ernesto has dissipated over western Mexico. However, the upper-level feature, showers and thunderstorms have survived the trip west. In fact, the satellite picture shows an impressive amount of cold top showers and thunderstorms along and off the west coast of Mexico. The patch of clouds near 20N120W is weakening Tropical Storm Gilma.
Most of the global mountains takes the upper-level system moving off the Mexico coast and gradually develops and intensifies a surface low pressure system that could easily become a tropical storm before the weekend is through.
If this happens, and there seems to be a good chance, it will have the new name, Hector.
While models take it west into early next week, a developing trough off the West Coast could turn this system north or even northeast. The GFS has this low directly affecting the southern and central Baja Thursday or so next week. The European has it somewhat farther west but not too far to the west of the southern Baja by the same time period.
These is the possibility that another surge of tropical moisture could move into Arizona and Southern California by the middle of next week.
I still believe the greatest amount of rain, at least partially relating to Norbert, occurs from southeast California to Arizona
The effects on Southern California are very much in question.
With low wind shear and warm water in its path for a while longer, it is likely that Norbert intensifies into at least a Category 2 storm.
For much of the last week the monsoon moisture flow into the Southwest has been completely shut down by dry westerly winds. This is about to change.
A big pattern change is underway, one that will completely shut down any chance of showers and thunderstorms for an extended time period.