Upcoming rain predictions

THE MODELS HAVE TRENDED SLOWER IN MOVING THE COLD FRONTAL RAIN BAND THROUGH OUR AREA AROUND MIDWEEK AND THIS SEEMS REASONABLE GIVEN THAT THE TROUGH WILL BE DEEPENING AS IT APPROACHES THE COAST. IT NOW LOOKS LIKE RAIN WILL BEGIN IN THE NORTH BAY ON WEDNESDAY BUT NOT MAKE IT SOUTH AND EAST THROUGH THE REST OF THE SF BAY AREA UNTIL LATE WEDNESDAY NIGHT OR EVEN THURSDAY MORNING. HAVE ADJUSTED THE POP GRIDS ACCORDINGLY. THE SOUTHERN EXTENT OF THE FRONTAL RAIN BAND IS EXPECTED TO REACH TO ABOUT THE MONTEREY PENINSULA ON THURSDAY MORNING. THEREAFTER…THE GFS AND ECMWF AGREE QUITE WELL IN PRODUCING ONLY ISOLATED LIGHT SHOWERS AS THE UPPER TROUGH MOVES THROUGH FROM LATE THURSDAY THROUGH FRIDAY EVENING. THE GEM MODEL…ON THE OTHER HAND…INDICATES MUCH MORE MOISTURE
WITH THE TROUGH AND THIS MODEL SPREADS ANOTHER ROUND OF WIDESPREAD RAIN ACROSS OUR AREA ON FRIDAY AND FRIDAY EVENING. HAVE KEPT RAIN CHANCES GOING THROUGH FRIDAY NIGHT…BUT CONFIDENCE IN THE FORECAST DECREASES CONSIDERABLY AFTER THURSDAY EVENING GIVEN MODEL DIFFERENCES. THERE IS CURRENTLY NO EXPECTATION FOR THUNDERSTORMS WITH THIS SYSTEM…BUT THIS WILL NEED TO BE LOOKED AT MORE CLOSELY AS WE DRAW NEARER TO THE PRECIP EVENT.

RAINFALL TOTALS WITH THIS SYSTEM LOOK TO BE MOSTLY AROUND A
QUARTER OF AN INCH OR LESS EXCEPT UP TO A HALF INCH OR MORE IN THE COASTAL MOUNTAINS…ESPECIALLY IN THE NORTH BAY. THESE TOTALS ARE BASED ON THE GFS AND ECMWF GUIDANCE AND HIGHER AMOUNTS WOULD OCCUR IF THE 00Z GEM SCENARIO WERE TO VERIFY.