18
FXUS66 KMTR 141504
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
804 AM PDT WED MAR 14 2012

.DISCUSSION...AS OF 2:31 AM PDT WEDNESDAY...RAIN CONTINUES TO FALL
ACROSS MAINLY THE NORTH BAY AND IN PORTIONS OF THE SANTA CRUZ
MOUNTAINS. RAINFALL TOTALS OVER THE PAST SIX HOURS INDICATE THE
HIGHEST AMOUNTS IN NAPA AND MARIN COUNTIES WITH UP TO AN INCH AND
A HALF...TO AROUND 0.5-1.0 INCH IN THE SANTA CRUZ MOUNTAINS.

SATELLITE IMAGERY SHOWS THE FRONTAL BAND THAT AFFECTED THE
DISTRICT YESTERDAY TO BE WELL TO THE SOUTH AND EAST. THE NEXT BAND
CAN BE SEEN MOVING SOUTH ACROSS NORTHERN CALIFORNIA. RAIN IS
EXPECTED TO DECREASE TODAY AHEAD OF THIS NEXT SYSTEM...THEN
INCREASE IN THE NORTH BAY THIS EVENING...AND OVERNIGHT TONIGHT IN
THE BAY AREA AS THE BAND SHIFTS SOUTHWARD. GREATEST RAINFALL
RATES...THOUGH...ARE FORECAST TO OCCUR FROM THE NORTH BAY
NORTHWARD...AT LEAST UNTIL FRIDAY WHEN ANOTHER IMPULSE FINALLY
KICKS THIS BAND SOUTH AND THROUGH THE DISTRICT.

THE UPPER TROUGH IS PROGGED TO APPROACH THE NORTHERN CALIFORNIA
COAST FRIDAY EVENING AND FRIDAY NIGHT. AS THIS TROUGH NEARS...A
COLD FRONT WILL MOVE QUICKLY ACROSS NORTHERN CALIFORNIA SPREADING
RAIN AND GUSTY NORTHERLY WINDS ACROSS THE ENTIRE DISTRICT FRIDAY
NIGHT. THE ASSOCIATED UPPER LOW WILL THEN DROP SOUTHWARD ALONG THE
COAST ON SATURDAY BRINGING A COLD AND UNSTABLE AIRMASS TO THE
AREA. THIS WILL LOWER SNOW LEVELS TO AROUND 2000-3000 FEET ON
SATURDAY AS WELL AS INCREASE THE POSSIBILITY FOR THUNDERSTORMS
WITH SMALL HAIL. THE SHOWERS WILL DECREASE ON SUNDAY AS HIGH
PRESSURE STARTS TO BUILD IN FROM THE WEST.

HIGH PRESSURE TO KEEP CONDITIONS DRY THROUGH ABOUT MIDWEEK...BUT
MEDIUM RANGE PROGS BRING IN THE POSSIBILITY FOR RAIN LATER IN THE
WEEK.

&&

.AVIATION...AS OF 8:00 AM PDT WEDNESDAY...RAIN CONTINUES ACROSS MOST
OF OUR AREA THIS MORNING. MODEL GUIDANCE MOVES THE RAIN THROUGH
THE BAY AREA THIS MORNING WITH JUST A FEW SHOWERS LEFT BY
LATE AFTERNOON. IFR/MVFR CIGS WILL CONTINUE WITH BRIEF PERIODS OF
VFR THROUGH THIS AFTERNOON. WINDS WILL MOSTLY STAY SOUTHERLY.
OVERALL VERY LOW CONFIDENCE WITH THE OVERALL PACKAGE DUE TO
UNCERTAINTY WITH THE TIMING OF RAIN PLUS CEILING HEIGHTS.

VICINITY OF KSFO...MVFR THROUGH MOST OF THE PERIOD. CURRENT CIGS
ARE AROUND 2500 FEET AND SHOULD STAY ABOVE 2000 FEET THROUGH THE
DAY. HOWEVER...NOT OUT OF THE QUESTION THAT A SHOWER COULD BRIEFLY
DROP THEM LOWER. GENERALLY SOUTHERLY WINDS CONTINUING AND
DECREASING LATER TODAY.

KSFO BRIDGE APPROACH....SIMILAR TO KSFO.

MONTEREY BAY AREA TERMINALS...GENERALLY MVFR CIGS ALTHOUGH VFR
: