After an interesting weather week, including very low elevation snowfall in Northern California followed by record-breaking cold and a strong storm in the San Diego area, a much moister and wetter pattern has developed across the entire state. A disorganized by moist and somewhat unstable system is currently moving ashore, bringing areas of rain and isolated thunderstorms this evening, especially on the Central Coast. Rain will taper off by morning but will begin to increase by later in the day on Friday ahead of the next system. This storm will be much stronger than the one curently affecting the state, and will bring a period of heavy rain and strong winds to the state. Thermodynamic profiles will also be favorable for convective development along the font and also in the unsettled post-frontal environment, so isolated thunderstorms will be possible through the weekend, mainly in the north. This is unlikely to be an exceptionally strong storm, but could bring local flooding and will probably make travel impossible over mountain passes by Saturday morning. The entire state will probably jet at least some rain out of this, and significant rainfall will fall even over much of SoCal. Again, rainfall will probably not be excessively heavy, with generally 1-2 inches in NorCal with locally up to 3-4 inches, and generally 0.5-1 inch in SoCal with up to 2-3 inches in the mountains. The very moist storms foreseen by the models last week and the week before have not materialized, and there is no real indication of large storms on the horizon. In fact, the GFS indicates a fairly benign pattern (actually a very mild one at that) developing by Monday and lasting right on through Christmas. This can always change, of course, and dynamical/statistical models do indicate a resurgence and eastward propagation of the MJO signal during the next week or two. This weekend’s rain will be beneficial, but hopefully we can get some more before the end of the month.
Below: Ice scapes in Davis, CA on December 9, 2009.