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[Printable]
403
FXUS66 KMTR 201000
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
300 AM PDT MON OCT 20 2014

.SYNOPSIS...A COLD FRONT WILL SPREAD RAIN ACROSS A PORTION OF OUR
AREA TODAY ESPECIALLY ACROSS THE NORTH BAY.. DRY WEATHER WILL
RETURN BY TUESDAY WITH WARMING EXPECTED THROUGH THE REST OF THE
WORK WEEK. ANOTHER CHANCE OF RAIN IS POSSIBLE BY THE END OF THE
WEEK.

&&

.DISCUSSION...AS OF 3:00 AM PDT MONDAY...SATELLITE AND ANALYSIS
SHOWS AN APPROACHING COLD FRONT ABOUT 150 MILES TO OUR WEST THIS
MORNING. THIS FRONT, WHICH HAS BEEN THE MAIN FOCUS OF ATTENTION
FOR THE FORECAST OVER THE PAST FEW DAYS,  WILL ADVANCE ACROSS OUR
CWA TODAY AND BRING A CHANCE OF RAIN TO OUR AREA. MODELS CONTINUE
TO REMAIN IN GOOD AGREEMENT THAT MOST OF THE RAIN WILL STAY WELL
TO OUR NORTH WITH JUST THE NORTH BAY LOOKING THE MOST LIKELY TO
LOCALLY PICK UP MORE THAN 1/4" WITH A TENTH AT THE MOST AROUND SF
BAY AND EVEN LESS TO THE SOUTH. TIMING BRINGS THE BEST CHANCE OF
RAIN TO THE NORTH BAY AROUND SUNRISE WITH COMMUNITIES FROM SF DOWN
TO MONTEREY LOOKING AT VERY LATE MORNING TO EARLY AFTERNOON. THE
FRONT WILL ADVANCE TO THE EAST AND BE OUT OF OUR AREA TONIGHT.

QUIET WEATHER RETURNS FOR TUESDAY THROUGH THURSDAY AS A RIDGE OF
HIGH PRESSURE ATTEMPTS TO BUILD INTO THE SOUTHWESTERN CONUS. WORTH
NOTING THAT THE MODELS HAVE BACKED OFF A BIT ON BUILDING THE RIDGE
AND NOW BRING ALMOST A ZONAL FLOW INTO CENTRAL CALIFORNIA. THIS
MEANS THAT HIGHS ARE NOT EXPECTED TO BE NEARLY AS WARM AS WE WERE
THINKING ON PREVIOUS SHIFTS. INSTEAD OF UPPER 70S TO UPPER 80S FOR
INLAND SPORTS BY THURSDAY, LOOKS MORE LIKE 70S TO LOWER 80S FOR MOST
AREAS. COASTAL COMMUNITIES SHOULD STAY MORE IN THE 60S TO MID 70S
INSTEAD OF UPPER 60S TO NEAR 80.

WITH LESS AMPLITUDE OF THE RIDGE, THE ODDS OF ANOTHER SYSTEM BEING
ABLE TO IMPACT OUR WEATHER INCREASES, AND NOW A CHUNK OF THE
MODELS BRING A LONGWAVE TROF NEAR THE WEST COAST FOR
FRIDAY/SATURDAY AND DEPICT A LONG FETCH OF MOIST AIR MOVING
ACROSS. IN FACT, THE OPERATIONAL GFS AND GEM (PLUS THE ENSEMBLE
MEAN) ALL BRING A FAIRLY VIGOROUS FRONT TO THE SF BAY REGION
DURING THIS TIME WITH NOTABLE RAINFALL AMOUNTS. HOWEVER, THE
ECMWF REMAINS MUCH DRIER AND ONLY HAS LIMITED AMOUNT OF RAIN
MAKING INTO THE NORTHERN PART OF THE CWA. DUE TO THE FACT THAT THE
GFS AND GEM HAVE BROUGHT DOWN THE STORM TRACK MUCH FARTHER TO THE
SOUTH COMPARED TO PREVIOUS RUNS AND THE ECMWF HAS FLIPPED FROM A
BLOCKING RIDGE, FEEL THE BEST COURSE OF ACTION IS TO TAKE A MORE
CONSERVATIVE APPROACH AND BRING A CHANCE OF RAIN FOR FRIDAY INTO
SATURDAY. THIS WILL NEED TO BE CLOSELY WATCHED AND IF THE ECMWF
(PLUS THE CURRENT DRY NAVGEM WHICH ONLY GOES OUT TOE SATURDAY) FLIPS
INTO THE WET CAMP THE POPS WILL NEED TO BE INCREASED QUITE A BIT.
ALSO WORTH NOTING OFF OUR MODEL SPECTRUM PAGE THAT THE SPREAD OF
SOLUTIONS FOR FRIDAY THROUGH ALL OF SATURDAY IS CONSIDERED HIGH
FOR ALL LOCATIONS NORTH OF MONTEREY BAY. THIS HIGHLIGHTS THE LOW
CONFIDENCE WE CURRENTLY HAVE FOR THE PERIOD BEYOND THURSDAY.

REGARDLESS OF THE RAIN, TEMPS SHOULD COOL AROUND 10 DEGREES IN
MANY SPOTS BY THE WEEKEND. BEYOND THAT POINT THE FOCUS OF THE RAIN
SHIFTS BACK TO THE NORTH.

&&

.AVIATION...AS OF 10:40 PM PDT SUNDAY...COASTAL STRATUS IS SLOWLY
SPREADING OVER THE SFO BAY AREA. CLOUDS SHOULD CONTINUE TO
INCREASE AS FRONTAL SYSTEM APPROACHES. BEST CHANCE OF ANY RAIN
WILL BE MID MORNING THROUGH EARLY AFTERNOON WHEN THE FRONT MOVES
THROUGH.

VICINITY OF KSFO...BECOMING MVFR. WINDS REMAINING UNDER 10 KT BUT
SWITCHING MORE SOUTHWEST ON MONDAY.

KSFO BRIDGE APPROACH...SAME AS KSFO.

MONTEREY BAY AREA TERMINALS...STRATUS HAS STAYED IN NRN MRY BAY
LEAVING MRY AND SNS CLEAR AT THIS TIME. MORE OFFSHORE STRATUS
MOVING TOWARDS MRY AND SNS WITH IFR CIGS. CIGS MAY BE HIGH ENOUGH
TO BE MVFR.

&&

.MARINE...AS OF 10:45 PM PDT SUNDAY...A FRONTAL SYSTEM WILL MOVE
INTO THE NORTHERN WATERS EARLY MONDAY MORNING. WINDS WILL BE
LIGHT SOUTHERLY IN THE NORTHERN WATERS AND LIGHT WEST TO NORTHWEST
IN THE SOUTHERN WATERS THROUGH TUESDAY. WINDS WILL SWITCH TO
NORTHWEST OVER ALL WATERS WEDNESDAY THROUGH FRIDAY. A LARGE
NORTHWESTERLY SWELL GENERATED BY A STORM IN THE GULF OF ALASKA
WILL ARRIVE AT THE COAST TONIGHT. LONG PERIOD FORERUNNERS WILL BE
ARRIVING TONIGHT WITH THE LARGER WAVES ARRIVING MONDAY.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .TDAY...SCA...ROUGH BAR ADVISORY FOR SF BAR FROM 11 AM
             SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 6 PM

&&

$$

PUBLIC FORECAST: BELL
AVIATION/MARINE: W PI

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