Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
529 PM PDT Thursday Jul 31 2014
Synopsis...high clouds are moving in from the west with low
clouds expected to return to the coast and in land valleys this
evening. Otherwise...the typical Summer weather pattern has
returned to the central coast with night/morning coastal low
clouds and fog stretching into the valleys and clearing skies in the
afternoon hours. Near normal temperatures and dry weather expected
through the forecast period.
Discussion...as of 2:00 PM PDT Thursday...so far it has been a mild
day around the forecast area. San Rafael and sfo are reporting
current temperatures of 70 degrees and Monterey is reporting a
current temperature of 64 degrees. However...it is warmer inland
with Concord reporting 81 and Livermore 89 degrees. Mostly clear
skies are being reported are being reported around the area.
However...the current visible satellite is showing low clouds
lingering over the coastal waters and along the coast. According
to The Fort Ord profiler the marine layer is approximately 1200
feet deep onshore winds expected overnight. Therefore...expect a
return of low clouds and fog to the coastal and inland valleys.
The 1200z European model (ecmwf) and gfs40 have initialized well with the current
synoptic pattern and remain in good agreement through the forecast
period. Both models maintain a ridge of high pressure over the
western Continental U.S. Through the weekend with a weak upper level trough
developing along the coast by the beginning of next week. At the
surface a thermal through positioned along the coast will promote
warm seasonal temperatures inland and cool temperatures along the
Aviation...as of 5:10 PM PDT Thursday...the marine layer has
compressed to around 1000 feet this afternoon and the increasing
northerly gradient is currently sweeping the stratus from the
coast from north to south. Low confidence with respect to the
onset time of stratus overnight tonight. Ceilings will likely come in
later than last night and clear earlier than this morning...however
there is a chance that ceilings will not return at all especially over
the North Bay and Bay area terminals. Will continue to monitor and
update as needed.
Vicinity of ksfo...VFR conditions expected through late tonight
with ceilings over koak returning after midnight if at all. Clearing
currently forecast for 17z Friday. West winds of 15-20 knots will
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR conditions expected through
this afternoon with ceilings expected to return around 03z. Clearing
expected between 18z-19z Friday. West winds will ease becoming
light and variable overnight.
Marine...as of 2:00 PM PDT Thursday...northerly flow will
increase over the coastal waters today as high pressure builds off
the West Coast. Winds will be strongest north of Point Reyes.
Gusty winds will also be possible in the San Francisco Bay this
afternoon and evening. The increased winds will produce steeper
wind waves and locally hazardous conditions. Northwest swell will
increase Friday and over the weekend.
... Arena to pt Reyes 10-60 nm
Small Craft Advisory...sf Bay north of the Bay Bridge until 9 PM
Public forecast: Larry
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