There finally seems to be a consensus building about the track and evolution of the cut-off low currently 800 miles southwest of CA. This low is rather large, and is drawing a stream of very moist subtropical air from a strong subtropical disturbance located 500 miles west of Baja CA. This subtropical moisture will have ample time to become significantly entrained by the southerly flow around the low. Deep southerly flow, combined with strong dynamic support and significant atmospheric instability as the low center approaches the coast and also as a result of the warm and moist tropical plume, will lead to widespread significant precipitation throughout Southern California from late Tuesday into Thursday morning. I do expect some flooding problems to arise, especially in burn areas. Intense precipitation is possible as there will be a good chance of thunderstorms and convective elements at times. There is some concern that these storms could become quite strong and train over the same areas for extended periods of time, leading to flash flooding. Rainfall may still be highly variable with this storm, but I do expect nearly all of SoCal to see 0.50 inches or more, with some favored slopes in the path of convective cells getting more than 5 inches. and even some coastal areas seeing 1-2+ inches as a result of thunderstorms. Interestingly, NorCal will largely miss out on the rain from this system, with Sacramento looking to be the northward extent of any precip (unless a deformation band can pop out some scattered convection on the north/northest side of the low) with generally 0.25 inches or less, and nothing in Eureka.
The entire state will be drying out by late in the day on Thanksgiving, and conditions will be dry and mostly clear (with some possible offshore winds) for the following 1-2 weeks. This sort of pattern is looking increasingly dire for NorCal–we need rain, and we need it now! Unfortunately, there is none whatsoever on the horizon…
Stay tuned; this storm could be merely wet for SoCal, or potentially something somewhat more newsworthy.
