Why We're All Wet
The totals in inches haven't been huge, but the rain has been persistent this month. A number of locations have either already or will surely set a record for number of March days with measurable precipitation. Today, the morning discussion out of the National Weather Service's Monterey office takes a crack at explaining the phenomenon (they like all-caps, don't ask me why):

THE PERSISTENCE OF THIS PATTERN IS BECOMING QUITE REMARKABLE. THE COMPLETE LACK OF A HUDSON BAY LOW AND THE STRONG POSITIVE ANOMALY THAT HAS PERSISTED OVER GREENLAND HAVE ESSENTIALLY BLOCKED SYSTEMS FROM MOVING DUE EAST INTO CANADA AND FORCED THEM SOUTH INTO THE US. THE OTHER MAJOR ANCHOR FOR MAINTAINING THIS PATTERN HAS BEEN THE PERSISTENT BROAD UPPER RIDGE NEAR 160W. THIS HAS BEEN SUPPORTED BY THE ALMOST CONTINUOUS KONA LOW TYPE SYSTEMS THAT HAVE PLAGUED HAWAII FOR ALMOST TWO MONTHS. THE HEATING GENERATED BY THE PERSISTENT CONVECTION HELPS BUILD THE RIDGE TO THE NORTH WHICH AMPLIFIES THE DOWNSTREAM TROUGHS WHICH HAPPENS TO BE THE SYSTEMS THAT HAVE BEEN TRACKING INTO CALIFORNIA FOR OVER A MONTH. FINALLY THE CONVECTION OVER AUSTRALIA THAT HAS SUPPORTED MULTIPLE TROPICAL CYCLONES IS ALSO HELPING TO ANCHOR THE LONG WAVE PATTERN. THE RIDGE BUILDING NORTH OF THIS CONVECTION HAS AMPLIFIED THE VERY DEEP TROUGHS THAT HAVE BEEN DEVELOPING EAST OF JAPAN WHICH HAS ALSO HELPED BUILD THE BROAD LONG WAVE RIDGE DOWNSTREAM NEAR 160W. UNTIL WE SEE ANY OF THESE THREE MAJOR ANCHOR POINTS BREAK DOWN THE UNUSUALLY WET AND COLD PATTERN FOR CALIFORNIA WILL CONTINUE. RIGHT NOW THIS LOOKS LIKE IT WILL CONTINUE INTO NEXT WEEK AT LEAST.