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Area forecast discussion 
National Weather Service San Francisco Bay area
931 am PDT Thursday Oct 23 2014

Synopsis...the weak tail end of an approaching Pacific weather
system will likely bring some light rainfall to the northernmost
portions of our district today...otherwise mild conditions are
expected. Friday looks to be mostly sunny and mild...but then a
somewhat wetter system will move in on Saturday and spread rain
chances across much of our area. After a few residual showers on
Sunday...dry conditions and seasonal temperatures are projected
into the first part of next week.

&& of 09:21 am PDT Thursday...a deep moisture plume
continues to impact northern California this morning with just
about all of the precipitation occurring north of the region.
Looking at the latest hrrr and other model output...have backed
off on precipitation across the North Bay and kept only a chance to
slight chance of rain north of the Golden Gate. Further south...we
can expect warmer temperatures this afternoon with plenty of high
clouds streaming over our northern areas. Otherwise...the forecast
remains on track for the remainder of the day.


Previous of 3:09 am PDT Thursday...mainly high
clouds are streaming across the northern two thirds of the County Warning Area at
this the southern edge of a system now affecting the
Pacific northwest moves through. Latest radar imagery shows echoes
are mainly remaining north of Sonoma and Napa counties at this
time and no appreciable rainfall has yet been picked up by
automated gauges. Expect the rain line to sag into the North Bay
today but not much rainfall is expected with this weak system.

After this weak system moves to the east...a stronger system is
prognosticated to affect more of the district late Friday night and
Saturday with rain chances extending as far south as well into
Monterey County by midday Saturday. Rainfall amounts of up to one
inch are possible across portions of the North Bay...with much
less from the Bay area south. As the upper low center moves
across...enough instability and colder air aloft for a slight
chance of thunderstorms across portions of the North Bay Saturday
afternoon. Showers to taper off on Sunday then drier conditions
are expected into the early part of next week. There continues to
be large differences amongst the medium range models regarding
rain chances next week. Thus have left some slight chance probability of precipitation
across the north for Tuesday and Wednesday but dry elsewhere. Low

&& of 4:30 am PDT Thursday...satellite image suggests
areas of stratus along the coastal hills of the sfo extending into
sfo and Oak as well as the North Bay valleys. The high clouds will
allow for slower clearing of the stratus and therefore burn-off
time is not until 18-19z despite the patchy nature of the stratus.

Vicinity of ksfo...MVFR conditions through 18z.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area stratus reported in the mry Bay
area this morning. Believe there may be an offshore drainage wind
that is keeping the coastal stratus out of the Bay. Feet Ord
profiler supports this. Therefore forecast has been changed to VFR
conditions for the day.

&& of 3:05 am PDT Thursday...high pressure continues
off the Southern California coast while low pressure is off
Vancouver Island. This is bringing light winds to the area with
stronger winds in the southern waters. Southerly winds will
increase Friday night and Saturday as a low pressure system
deepens off the Oregon coast. High pressure will build off the
California coast Sunday and Monday after the low moves inland.


Mtr watches/warnings/advisories...


Public forecast: rgass
aviation/marine: west pi

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