Several systems have brought rain and cool temperatures to NorCal over the past few days–keeping soils saturated and continuing to build up the snowpack, but not causing any significant problems. A somewhat stronger system will move in later tomorrow, riding a fairly strong dip in the jet stream over NorCal. Widespread moderate precipitation accumulations are expected, with locally heavy rates of precipitation at times. Winds will be breezy to locally windy, but again, no serious problems are anticipated. With a rather classic baroclinic setup, the cold front will be preceded by warm air advection and followed by a substantial drop in temperatures aloft, leading to steep lapse rates. Combined with some dynamic lift and curvature of the column until the back edge of the trough moves overhead, showers and isolated thunderstorms of the popcorn variety are likely in the post-frontal atmosphere (actually, haven’t seen that in a while). SoCal will see some precipitation from this system, but it should not be heavy. Once the weekend system moves out, I would expect the state to be essentially dry until next weekend. Even then, only light precipitation is expected in NorCal. The GFS has been indicating that a zonal jet will begin to inch back south by days 7/8, possibly bringing wet and unsettled weather back to the state. Next week, however, enjoy the “green-up” of vegetation that will occur with the ample sunshine and moist soils…
