Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
456 PM PDT Monday Aug 3 2015
Synopsis...onshore flow and the marine influence will maintain
cooler than average daytime temperatures across the region through
Tuesday. A modest warming trend is then expected Wednesday and
Thursday as high pressure builds across the region. Aside from
overnight and early morning clouds and patchy fog...dry weather
conditions are forecast to continue.
Discussion...as of 02:31 PM PDT Monday...quiet weather
conditions persist over the region this afternoon with just about
all inland areas under mostly clear skies. However...do see a few
high clouds streaming in from the southwest ahead of an
approaching weak middle/upper level disturbance. This short-wave
will push across the region through Tuesday...yet expecting dry
weather to persist given limited moisture aloft. Meanwhile...the
deep marine layer in place should result in a return of coastal
stratus tonight that will spread inland during the early morning
hours on Tuesday. Temperatures will also remain on the cool side
of normal with continued onshore flow and weak disturbances moving
across the region.
A slight warming trend can then be expected for Wednesday and
Thursday as the ridge over the Desert Southwest builds westward.
This warm-up will be short-lived however as the ridge shifts
eastward ahead of the next middle/upper level cut-off low forecast to
approach central California late in the week. As the system
approaches...daytime temperatures will cool slightly...especially
over inland areas. While the forecast models show there being a bit
more instability and middle/upper level support with this system...the
moisture aloft continues to be very limited. Thus...will maintain a
dry forecast at this time as the upper level low moves inland. Will
closely monitor the latest forecast guidance in the coming days for
any potential of thunderstorms on Friday and Saturday. Again...the
biggest concern would be fire weather impacts if dry thunderstorms
where to develop.
As the aforementioned system shifts further inland late in the
weekend...concern for convection diminishes. The forecast models
then develop a long-wave trough off along much of the West Coast
heading into early next week. This would likely result in ongoing
dry weather conditions and temperatures generally near seasonal
Aviation...as of 4:50 PM PDT Monday...for 00z tafs...clear skies
prevail across the region this afternoon. MVFR/IFR ceilings will
return overnight across area terminals. Moderate and locally
gusty winds will continue through this evening then ease
overnight. Moderate confidence.
Vicinity of ksfo... VFR conditions will prevail through this
evening. MVFR ceilings projected to return after 05z tonight.
Moderately strong west winds around 15 to 20 knots...with gust to
25kt will continue through this afternoon. Winds will ease to
around 10 knots overnight.
Ksfo bridge approach... similar to ksfo.
Monterey Bay area terminals... VFR conditions will prevail through this
evening. MVFR/IFR ceilings projected to return after 07z tonight.
Moderately west winds around 10 to 15 knots...with gust to 20 knots
will continue through this afternoon. Winds will ease to around 5 knots
Marine...as of 2:39 PM PDT Monday...predominately light to
moderate winds and calm seas are forecast through tomorrow. The
strongest winds will be over the northern San Francisco Bay this
afternoon... especially near the Golden Gate Bridge and Angel
Island. Winds increase and shift towards the northwest midweek.
... Bay until 10 PM
Public forecast: rgass
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