FXUS66 KMTR 041725
AFDMTR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN FRANCISCO BAY AREA CA
924 AM PST FRI DEC 4 2009

.DISCUSSION...AS OF 9:15 AM PST FRIDAY...AFTER A COLD MORNING FOG IS
STILL PREVALENT IN THE INTERIOR VALLEYS OF THE DISTRICT. TEMPS THIS
MORNING ARE IN THE 30S AND 40S...WITH LOWER 50S IN THE HILLS.

THE LATEST NAM12 AND GFS MODELS ARE INDC A SHIFT IN THE FCST
THINKING FOR SUN THROUGH MON. WILL WAIT TIL THE 12Z ECMWF...WHICH
WAS TRENDING COLDER TOO BEFORE MAKING ANY CHANGES. HOWEVER...IT IS
LOOKING LIKE IT COULD BE COLD AND SHOWERY SUN NIGHT/MON MRNG WITH
LOW SNOW LEVELS. IF IT CLEARS OUT MON NIGHT THERE COULD BE A FREEZE.

FOR NOW NO UPDATES...WILL WAIT TIL THE 12Z ECMWF COMES IN BEFORE
MAKING ANY CHANGES.

&&

.AVIATION...AS OF 4:07 AM PST FRIDAY...LIGHT WINDS AND AREAS OF LOW
CLOUDS AND FOG ARE ONCE AGAIN IN PLACE THROUGHOUT THE BAY AREA THIS
MORNING. VLIFR VISIBILITIES AND IFR/LIFR CIGS ARE PRESENT OVER A
NUMBER OF SF BAY TERMINALS. THESE CONDITIONS WILL MOST LIKELY
PERSIST INTO THE LATE MORNING HOURS DUE TO A NUMBER OF FAVORABLE
CONDITIONS. WINDS ARE LIGHT...THEREFORE NOT MUCH MIXING. A MORE
DEFINED MARINE INVERSION IS DEVELOPING...ALONG WITH A WEAK UPPER
LEVEL TROUGH THAT WILL MOVE IN AND ONLY FURTHER ENHANCE THE MARINE
LAYER. A HIGH LEVEL CLOUD SHIELD AND A LOW SUN ANGLE WILL HELP KEEP
CONDITIONS COOL AND STABLE.

VICINITY OF KSFO...A 400-500 FOOT CIGS WITH 4-5SM VSBY SHOULD
STAY IN PLACE OVER THE KSFO TERMINAL THROUGH 1730Z. A MORE
PESSIMISTIC OUTLOOK ON THE BURNOFF TIME WAS TAKEN WITH THE 12Z SFO
TAF DUE TO THE NOTED FAVORABLE CONDITIONS FOR EXTENDED FOG COVERAGE.
WINDS ARE EXPECTED TO BECOME LIGHT ONSHORE THIS AFTERNOON.

KSFO BRIDGE APPROACH...CONDITIONS SIMILAR TO KSFO TERMINAL WITH
IFR/LIFR CIGS AND MVFR VSBY THROUGH THE MID MORNING HOURS.
EXPECTING SCATTERING OUT/CLEARING OF FOG/STRATUS BTWN 17-18Z.

MRY BAY AREA TERMINALS...CURRENT CONDITIONS ARE CLEAR WITH VFR CIGS
AND VSBY...HOWEVER KEEP IN TEMPO GROUPS FOR POSSIBLE SUNRISE
SURPRISE FOG FORMATION AROUND KMRY AND KSNS TERMINALS. WITH THE
TERMINALS RECENTLY REPORTING S-SE DRAINAGE WINDS...HAVE HIGHER
CONFIDENCE IN CONDITIONS REMAINING CLEAR.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
    TDA...NONE

$$

PUBLIC FORECAST: MHS
AVIATION/MARINE: TENTINGER

NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO