000
FXUS66 KMTR 272358
AFDMTR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA
345 PM PST MON DEC 27 2010
.DISCUSSION...AS OF 1:45 PM PST MONDAY...MAIN FORECAST PROBLEM IS THE
SYSTEM GATHERING STRENGTH SOUTH OF THE ALEUTIAN ISLANDS NEAR 160W. IN
THE MEANTIME...FLAT RIDGE OF HIGH PRESSURE REMAINS OVER THE DISTRICT.
TEMPS THIS EARLY AFTERNOON ARE MAINLY IN THE 50S...WITH A FEW 40S IN
THE HILLS AND LOWER 60S IN INTERIOR MONTEREY AND SAN BENITO
COUNTIES.
MODELS TAKE THE NEXT SYSTEM AND DRIVES IT TO THE COAST. THE 12/18Z
GFS INTENSIFIES THE SYSTEM AS IT MOVES TO THE COAST. THE ECMWF ALSO
HAS IT QUITE STRONG...HOWEVER NOT AS POWERFUL AS THE GFS. AMSU
IMAGERY IS INDC A PLUME OF 1.25 INCHES OF TPW HEADING TO THE COAST...
WHICH THIS SYSTEM TAPS INTO. ALONG WITH VERY STRONG ISENTROPIC LIFT
AND WINDS PERPENDICULAR TO THE COASTAL RANGES THERE COULD BE HEAVY
RAIN AT TIMES LATE TUESDAY AFTN AND NIGHT. CONSIDERED ISSUING A WIND
ADVISORY FOR THE COASTAL ZONES FOR LATE TUESDAY INTO TUESDAY NIGHT...
BUT WITH THE DIFFERENCES IN MODEL SOLUTIONS HELD ON ISSUING ONE. THE
MID SHIFT WILL HAVE THE 00Z MODELS TO LOOK AT...WITH HOPEFULLY BETTER
MODEL CONSENSUS.
A STRONG COLD FRONT THAT WILL BE ACCOMPANYING THIS SYSTEM WILL MOVE
THROUGH THE DISTRICT TUESDAY NIGHT/WEDNESDAY MORNING. THIS WILL USHER
IN MUCH COLDER AIR AS THE FLOW BECOMES NORTHERLY. HAVE KEPT A MENTION
OF SHOWERS ON WEDNESDAY...WITH EVEN A FEW SNOW SHOWERS IN THE HILLS
ON WEDNESDAY NIGHT.
RIDGING WILL BRING DRY WEATHER TO THE DISTRICT THURSDAY THROUGH
FRIDAY. IT COULD BE QUITE COLD THURSDAY NIGHT...DEPENDING ON THE
CLOUD COVER OR HOW MUCH WIND THERE IS.
FRIDAY NIGHT THROUGH THE NEW YEARS WEEKEND...MEDIUM RANGE MODELS ARE
IN COMPLETE DISAGREEMENT. THE GFS KEEPS A RIDGE OVER THE DISTRICT FOR
DRY WEATHER. ON THE OTHER HAND...THE ECMWF CUTS OFF AN UPPER LOW AND
PARKS IT ALONG THE CENTRAL CALIFORNIA COAST. THE GFS ENSEMBLES
GENERALLY FAVORED THE GFS SOLUTION WHEREAS THE ECMWF ENSEMBLES WERE
CLOSE TO THE ECMWF SOLUTION. THEREFORE...HAVE KEPT THE FORECAST AS IS
FOR THIS PERIOD...TOWARDS CLIMATOLOGY.
&&
.AVIATION...AS OF 3:45 PM PST MONDAY...MID AND HIGH LEVEL CLOUDS ARE
MOVING OVER THE AREA. GOING FORECAST FOR VFR INTO THE EVENING LOOKS
GOOD. DURING THE OVERNIGHT THE PROBABILITY IS MODERATE TO HIGH THAT
LOW CLOUDS AND SOME FOG WILL REDEVELOP.
VICINITY OF KSFO...LIGHT WINDS AND VFR THROUGH THE EVENING. LOCAL
PRESSURE GRADIENTS ARE FLAT. MVFR CEILING AND VISIBILITY IS FORECAST
BY 11Z.
KSFO BRIDGE APPROACH...SIMILAR TO KSFO.
MONTEREY BAY AREA TERMINALS...LIGHT WINDS WITH HIGH CLOUDS MOVING IN
THROUGH THE EVENING. MODERATE CONFIDENCE VFR CONTINUES.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC FORECAST: MHS
AVIATION/MARINE: EVANS/CANEPA
