THIS BACK YARD GETTING HAMMERED. THE AREA WAS UNDER A FLOOD ADVISORY. >>> LET'S BRING IN FIRST ALERT METEOROLOGIST PAUL HEGGEN. IT REALLY DEPENDS WHERE YOU WERE BECAUSE IN SOME PARTS OF THE BAY AREA THEY WERE GETTING HAMMERED. >> YEAH. WE HAD HEAVY RAIN AT OUR HOUSE SUNDAY NIGHT, BUT WE'RE TALKING ABOUT THE SCATTERED NATURE OF THE SHOWERS AND THUNDERSTORMS IN THE BAY AREA. I'LL TALK ABOUT THE SETUP WHY THIS EVENT IS A BIT DIFFERENT AND WE'LL LOOK AT OUR 3D MODEL OF THE NORMAL CLOUDS OVER THE BAY AREA. THESE FLAT CLOUDS THAT PRODUCE MOST OF OUR RAIN, THEY'RE ASSOCIATED WITH AIR THAT IS FORCED TO GO UP. THAT'S USUALLY HOW WE GET RAIN CHANCES HERE. THESE CLOUDS DON'T GROW SPONTANEOUSLY BECAUSE THE AIR NEAR GROUND LEVEL IS COOL BY THE PACIFIC OCEAN. AIR IN THE UPPER LEVELS OF THE ATMOSPHERE IS WARM COMPARED TO THAT SURFACE LEVEL AIR AND THAT MEANS ANY AIR THAT STARTS TO RISE WILL WARM DOWN. WITH THE HEART OF THE STORM SYSTEM CLOSE TO US, IN THE UPPER LEVELS OF THE ATMOSPHERE TODAY THE AIR HAS BEEN COLD, SO WE'VE SEEN THE CLOUDS GROWING AND GROWING FROM SHOWERS INTO ACTUAL THUNDERSTORMS, EVEN A SEVERE THUNDERSTORM WARNING FOR SAN MATEO COUNTY AROUND 4:00 THIS AFTERNOON AND THAT THUNDERSTORM WAS ROTATING A BIT, SOMETHING WE USUALLY DON'T SEE AROUND THE BAY AREA. DARREN WILL TALK MORE ABOUT THAT AT 5:30, BUT THERE ARE STILL SOME THUNDERSTORMS OUT THERE RIGHT NOW ASSOCIATED WITH THE HEART OF THIS STORM SYSTEM. LET'S LOOK AT THE BIG PICTURE PERSPECTIVE WHY THIS IS HAPPENING. THE STORM SYSTEM IS JUST PARKED VERY CLOSE TO US RIGHT OFF THE COAST. IT'S GOING TO BE SENDING SHOWERS AND THUNDERSTORMS ACROSS THE BAY AREA AGAIN TUESDAY. THAT IS FINALLY GOING TO LOSE ITS INFLUENCE BY WEDNESDAY, DOWN TO A FEW LINGERING OFF AND ON SHOWERS AND ANOTHER STORM WAY OUT IN THE PACIFIC WILL TRY TO HEAD OUR WAY, A LOT OF UNCERTAINTY ON THAT ONE. PLENTY OF RAIN NOW, ESPECIALLY ON THE EAST SIDE OF THE BAY MOVING UP FROM FREMONT OVER THE EAST BAY HILLS INTO THE TRI-VALLEY. THERE HAVE BEEN LIGHTNING STRIKES THE PAST COUPLE HOURS, BUT THE ONE SEVERE THUNDERSTORM WARNING, MORE SCATTERED SHOWERS AND THUNDERSTORMS LIKELY HEADING THROUGH TONIGHT AND THEN WE'LL SEE ACTIVITY PICKING UP AS WE HEAD THROUGH THE MIDDAY AND AFTERNOON HOURS TOMORROW. SOME RAIN TO BEGIN THE DAY, SO ALLOW EXTRA TIME FOR THE MORNING COMMUTE, BUT DURING THE AFTERNOON I THINK IT'S THE LAST ROUND OF REALLY WIDESPREAD RAINFALL WE'LL SEE IN ASSOCIATION WITH THIS PARADE OF SYSTEMS. THAT QUIETS DOWN TO OFF AND ON SHOWERS LATE TOMORROW EVENING, SHOWERS POSSIBLE WEDNESDAY, BUT THEY'LL BE MUCH FEWER AND FARTHER BETWEEN. WE FINALLY START TO GET A BREAK AND ACTUAL DRY WEATHER IS IN THE FORECAST THURSDAY. HOW MUCH ADDITIONAL RAIN? WE'RE TALKING ABOUT A HALF INCH TO OVER AN INCH AND A HALF POSSIBLE IF SOME OF THOSE STORMS MANAGE TO TRAIN OVER THE SAME AREA OVER AND OVER AGAIN. IT'S A SIMILAR RANGE OF POSSIBILITIES FOR THE SOUTHERN HALF OF THE BAY AREA. THIS IS FALLING ON SATURATED GROUND, OVER 4 INCHES OF RAIN SO FAR IN BEN LOMOND. THREE-QUARTERS INCH IN SAN JOSE AND 2 INCHES IN LOS GATOS. ABOUT AN INCH OF RAIN IN CONCORD, BUT JUST DOWN THE ROAD TO DANVILLE, THEY'VE HAD OVER 2 WITH INCHES OF RAIN. EVERYTHING IS REALLY DEPENDENT ON EXACTLY WHERE YOUR LOCATION IS AND IF THOSE HEAVIER DOWNPOURS HAVE PARKED, JUST OVER A HALF INCH OF RAIN SO FAR IN DOWNTOWN SAN FRANCISCO, BUT OTHER SENSORS AROUND THE CITY ADDED UP QUITE A BIT MORE AND THERE'S BEEN OVER 2 INCHES IN NOVATO AND APPROACHING 3.25 INCHES SO FAR IN SANTA ROSA AND THERE IS MORE TO COME, WHICH IS WHY WE HAVE THE FLOOD WATCH IN EFFECT UNTIL 10:00 WEDNESDAY MORNING. THE WINDS ARE STILL GOING TO BE SUBSTANTIAL AS WE HEAD THROUGH THE NEXT FEW HOURS, BUT THEY'LL DIE DOWN. THIS IS OUR HOUR-BY-HOUR WIND CHART FOR THE BAY AREA. YOU CAN SEE AS THE COLORS BECOME A LITTLE LESS OMINOUS, THAT'S WHEN THE WINDS LATE TONIGHT INTO EARLY TOMORROW MORNING WILL RELAX TO A MUCH GREATER DEGREE, BUT IT'S DEFINITELY IT BLUSTERY THIS EVENING AND THERE'S MORE SNOW THAT WILL ADD UP IN THE SIERRA, ANOTHER FEW INCHES OF SNOW AT LAKE LEVEL, OVER A FOOT POSSIBLE IN SOME OF THE HIGHER ELEVATIONS BEFORE THE SYSTEM STARTS TO FINALLY LOSE ITS INFLUENCE. LET'S LOOK AT THE SEVEN-DAY FORECAST, RAIN AND THUNDERSTORMS STILL POSSIBLE TOMORROW, A FEW SHOWERS WEDNESDAY. THURSDAY LOOKS LIKE A DRY DAY WITH TEMPERATURES IN THE LOW 60s AND THEN TONS OF UNCERTAINTY FRIDAY, SATURDAY, SUNDAY, AND MONDAY. WE'VE KIND OF BROAD BRUSHED THE PHRASING OF THE FORECAST TO SAY SHOWERS ARE POSSIBLE, BUT OUR DAY-BY-DAY RAIN CHANCES ARE LOWER THAN 50/50 THROUGH THE WEEKEND INTO EARLY NEXT WEEK, A LOT OF UNCERTAINTY REGARDING WHERE THE NEXT
