Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
350 am PDT Sat Oct 10 2015
Synopsis...dry weather will continue into early next week...along
with near normal to above normal temperatures. A low pressure
system currently located over the Baja California peninsula will move west
out over the Pacific waters and may be a factor in our weather by
Discussion...as of 3:50 am PDT Saturday...satellite imagery
shows stratus along the coast from Point Sur northward...and
extending locally into the San Francisco Bay. Web cameras show a
shallow layer of fog spreading into San Francisco. The Fort Ord
profile indicates a very shallow marine layer depth...probably
only a couple hundred feet deep. Patchy dense fog is likely along
the coast and locally inland early this morning as this shallow
marine layer tries to spread inland.
High pressure aloft will weaken slightly today as an upper level
trough moves onto the Pacific northwest coast. Thus slightly
cooler temperatures are expected today with an increase in clouds
over the north...and a stronger onshore flow. Similar conditions
are expected on Sunday...with highs ranging from the upper 60s to
middle 70s coast...to the 80s to middle 90s well inland.
On Monday and Tuesday...warmer temperatures are expected as the upper
ridge rebuilds over California. Meanwhile...the upper level cutoff
low currently located over southern Baja California California will slowly
migrate to the west ending up west of the Southern California
coast by early next week. Early in the week the low is prognosticated to
remain too far to the west to affect our area...but by Wednesday
and Thursday...this low is forecast to open up into a trough and
finally move onshore across Southern California. Again the GFS
brings a better chance of precipitation to our area than does the European model (ecmwf)
which is much drier...thus have left slight chance probability of precipitation in for the
southern most sections of the County Warning Area Wednesday and Thursday.
Confidence remains low...however.
Aviation...as of 1:02 am PDT Saturday...the current satellite
water vapour image is showing a ridge of high pressure positioned
over the San Francisco and Monterey Bay area this morning. The infrared
satellite image is showing little to no high clouds over
California...promoting radiational cooling. The Fort Ord profiler
and the San Francisco radiometer are both indicating a compressed
marine layer with a subsidence inversion present. Dew point
depressions are indicating a near saturated surface environment.
This all adds up to a foggy morning around the forecast
area...with dense fog possible through sunrise.
Vicinity of ksfo...LIFR to vlifr conditions are anticipated to
prevail this morning with the possibility of dense fog 1/4sm
through at least 1400z.
Confidence is moderate.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...VFR conditions are expected to
deteriorate LIFR shortly. However...VFR will prevail shortly after
Confidence is moderate.
Marine...as of 3:01 am PDT Saturday...generally light northerly
winds are expected to prevail across a majority of the coastal
waters today. However...moderate winds are anticipated south of
Point Sur through Sunday evening. Please keep in mind that winds
will become gusty along the coast with the afternoon sea breeze. A
moderate period west to southwesterly swell generated by hurricane
oho will continue to pass through the waters today. A slightly
larger northwest swell will enter the waters on Sunday.
Public forecast: Sims
Visit US at www.Weather.Gov/sanfrancisco
Follow US on facebook and twitter at: