Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1001 PM PST Thursday Jan 29 2015
Synopsis...dry conditions are expected to continue through next
week with chances of rain only over far northern California. Temperatures
will remain several degrees above normal for the next seven days.
Discussion...as of 9:00 PM PST Thursday...stagnant pattern
continues over the area with ridging to the north and an upper
level trough to the south. Light winds aloft will allow a shallow
inversion layer to form near the surface overnight. As a result
areas of low clouds and fog may form again.
The upper level trough will develop into a closed low over
Southern California on Friday. Moisture drawn up from this system
will spread into the southwestern US. The low will be too far
south and east of the district to produce any wraparound showers
into our County Warning Area. Instead an upper level ridge will build off the
California coast behind the low. Northerly winds will increase
aloft which will bring wind gusts up to 25-30 miles per hour in the north
and East Bay hills Friday night through Saturday night. These
winds should be enough to mix out the fog and haze for this
weekend leaving clear skies.
The upper ridge will move over the area Saturday and Sunday then
flatten out on Monday as a weak storm moves into the Pacific
northwest. Latest European model (ecmwf) and GFS keep all rain north of the County Warning Area so
all chances of rain have been removed from the forecast. Another
ridge builds off the coast Tuesday through Thursday for continued
dry weather. There is no clear indication on when the next rain
Aviation...as of 10:01 PM PST Thursday...for 06z tafs. Skies
remain clear over the terminals for now but some stratus is
developing along the coast near pt Reyes and along the San Mateo
coast. Tafs will show some possible low ceilings towards sunrise but
expect any low clouds and fog that do develop to mix out by 18z
and be patchy in nature.
Vicinity of ksfo...VFR through midnight...some concern for another
round of low ceilings to develop by sunrise. Low confidence. If ceilings
do form expect them to mix out by 18z and be patchy in coverage.
Ksfo bridge approach...VFR overnight with possible ceilings impacting
approach between 14-17z Friday.
Monterey Bay area terminals...VFR this evening with possible low
ceilings around sunrise Friday...but mixing out quickly by 17z.
Marine...as of 10:01 PM PST Thursday...northerly winds will
increase overnight through Friday before gradually easing by
Saturday afternoon. The increasing northwest winds will produce choppy
seas with a fresh well Friday into Saturday morning. Building high
pressure the second half of the weekend into early next week will
bring lighter wind and seas to the waters.
... Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm
Public forecast: west pi
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