2008

Quick update this evening. Dry and generally mild weather continues over CA thanks to strong offshore winds resulting from the steep temperature differential between coastal CA and western NV. Powerful gusts will affect mountain peaks across the state for the next few days, and strong breezes will be widespread (leading to chilly overnight and early morning windchill values in some places). The pattern will begin to undergo a subtle change over the holiday weekend as a weak loop of retrogressive jet energy slips to the south over  Nevada and interior northeastern CA. The low will quickly pinch off into a fairly deep cutoff low over the northern Sacramento Valley by Monday, moving slowly west-southwest to the coast. As it does so…the low will begin to pick up a bit of upper-level moisture from convective and advective processes, especially as it nears the coast. Temperatures aloft will be quite cold with this cutoff low–probably below -3 C (and perhaps below -5 C) at 850 mb in NorCal and below 0 C in the south. This will generate very steep lapse rates over the region, and even with rather sparse moisture this system may be able to generate some convective activity (with very low snow levels–locally 1000 feet or lower in the north). The models have been trending steadily deeper…colder…moister…and further  west with this system, so future trends will have to watched closely. Right now, this does not appear to be a significant precipitation event for any of the state, but as most of you probably realize by now, this can change…