A cut-off low pressure area is currently approaching Southern California. Rainfall over land has been sparse indeed thus far, though this will probably change from about Santa Barbara southward as the night progresses. Cooling cloud tops on infrared satellite imagery indicates that some convection is ongoing, but there does not (at this time) appear to be any lightning associated with the area of enhanced upper-level divergence on the east side of the low. While some isolated thunderstorms are certainly possible overnight and maybe into tomorrow from about Los Angeles southward, I don’t expect this to be an especially notable event.
On average, more precipitation will fall with the Saturday/Sunday system slated to affect primarily Northern California (up to around 0.5 inches or so). Isolated thunderstorms will be possible once again as cold air advection aloft steepens lapse rates in a moist environment. [ad#post-ad-w]The models have been highly incoherent lately with regard to the pattern evolution after days 3/4, but there does appear a bit of consensus developing between the GFS and the ECMWF on the development of an active pattern next week. A more organized and southerly jet stream will consolidate off the coast and act to break down the blocking ridge over the West Coast even more completely be early next week. Both models agree that precipitation will increase once again by midweek, perhaps culminating in a fairly significant storm event next Friday.
Though this is still a week out and the models have been unreliable lately, I do think there is probably a good chance this will come to pass. After the potential Friday system, the GFS continues to indicate quite an active flow pattern over the East Pacific for the foreseeable future. Though hydrological issues appear quite unlikely through at least midweek, the late-week system may begin to present some problems if it develops as currently progged. Stay tuned.
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