Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
226 PM PDT Tuesday Jul 29 2014
Synopsis...monsoon/subtropical moisture will continue to filter
in over the forecast area tonight and tomorrow. This will result
in partly cloudy skies and a relatively warm night due to extra
humidity in the air. The airmass will begin to dry tomorrow
evening so expect slightly cooler less humid nights. Otherwise...dry
conditions and near normal temperatures can be expected through
the remainder of the week.
Discussion...as of 2:26 PM PDT Tuesday...mostly clear skies are
present over the forecast area this afternoon with stratus
apparent over the coastal waters. The current satellite water
vapour image is showing moisture streaming into Southern
California and portions of our forecast area. Satellite blended
total precipitable water is showing values 1.0 to 1.25 inches
around the central California which is about 110 to 120 percent of
normal. This moisture will primarily result partly cloudy skies
and a warm humid night tonight.
The 1200z European model (ecmwf) and gfs40 have initialized well with the current
synoptic pattern. Both forecast models begin to move the
monsoon/subtropical moisture out of the forecast area Wednesday.
This will result in clearing skies and lower humidity
values...slightly cooler evening temperatures. Otherwise looks
like relatively mild weather through the beginning of next week
with near normal temperatures expected.
Aviation...as of 10:47 am PDT Tuesday...
Not a solid stratus shield this morning. Little onshore push from
Pacific stratus and then some early morning development directly
over the Bay. This looks to be the pattern again for tonight and
the models support this. This favors Oak for stratus and low ceilings
in the early morning more than sfo.
Vicinity of ksfo...skies have cleared and VFR prevails. Will
forecast persistence for tonight and models suggest some patchy
stratus around the terminal tonight but will go with no ceilings given
the occurrences of last night.
Ksfo bridge approach...similar to ksfo...patchy ceilings will impact
portions of the approach but indications are for this to be hit or
miss and so difficult to pin down exactly. Low confidence.
Monterey Bay area terminals...VFR this afternoon. Ceilings return
tonight after 05z.
Marine...as of 10:48 am PDT Tuesday...slight chance of showers
possible this morning as monsoon moisture remains over the region.
Otherwise...northerly winds will prevail over the coastal waters.
Moderate to locally strong northerly winds will be possible north
of Point Reyes this evening and Wednesday. Seas will generally be
gentle through the remainder of the week.
... Arena to pt Reyes 10-60 nm from 9 PM
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm from 3 am
Small Craft Advisory...sf Bay north of the Bay Bridge until 9 PM
Public forecast: Larry
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