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Area forecast discussion 
National Weather Service San Francisco Bay area
1043 am PDT Sat Apr 18 2015

Synopsis...high pressure across much of the West Coast will
maintain above average inland temperatures with cooler conditions
near the coast. Conditions cool region-wide early in the week with
unsettled weather possible middle/late week as upper level troughing
develops off of the West Coast.

&&

Discussion...as of 9:00 am PDT Saturday...widespread stratus
prevails across the region this morning. The Fort Ord profiler
shows the marine layer deepened to around 1400 feet this morning
in response to a weak short wave that is approaching from the
north. Latest satellite imagery reveals stratus is beginning to
erode over the Salinas and Santa Clara valleys. Low clouds are
anticipated to rapidly clear over the next couple of hours making
way for a beautiful day. The short wave mentioned above is
forecast to slide south with very little impact to our area other
than an expanding marine layer and associated cooling along the
coast. Inland temperatures are not expected to once again climb
into to the upper 70s and 80s this afternoon.

As the weekend progresses the weak short wave is prognosticated to veer
offshore and cut off to the west of our area. Again other than an
enhanced marine layer conditions will remain warm and dry with
cooler conditions along the coast.

This system will slide south off the central California coast on
Monday. Models indicate there is the potential for an isolated
shower or thunderstorm over the Gabilan and Santa Lucia ranges
Monday afternoon due to increased instability and a slight
increase in middle-level moisture over the southern half of the
region.

Cooler temperatures are in store across the region through the
remainder of the week as a broad long wave trough sweeps through
the region. Another cut off low is forecast to develop off the
northern California coast Tuesday night into Wednesday and follow
a similar trajectory as its predecessor. This low will bring and
slight chance of isolated showers across the region.

From previous discussion... the medium range models keep an
unsettled pattern over much of the West Coast through the
remainder of the week. The European model (ecmwf) and CMC both show a somewhat
stronger system dropping southward along the coast Friday into
Saturday that would bring more widespread rainfall to the region.
However...there remains a great deal of uncertainty in the run-to-
run and model-to-model solutions this far out. With all that
said...will keep temperatures near or slightly below seasonal
averages late in the forecast period along with a slight chance of
precipitation.

&&

Aviation...as of 10:45 am PDT Saturday... marine stratus
has retreated rather rapidly after an overnight push inland. VFR
conditions are expected through the remainder of the daylight
hours today with predominately light winds. Onshore flow will
increase this afternoon with possible gusts 20 knots or less. WRF model
struggling with the latest marine stratus scenario... so leaning
closer towards NAM for guidance tonight despite NAM overestimating
stratus for the last several months. MVFR/IFR ceilings from marine
stratus expected between 03-10z tonight depending on location.

Vicinity of ksfo... VFR through daylight hours. Onshore flow this
afternoon with gusts up to 20 knots. IFR/stratus returns tonight between
04-08z.

Sfo bridge approach...similar to ksfo.

Monterey Bay area terminals... VFR through daylight hours. Weak to
moderate onshore flow this afternoon. IFR/stratus returns tonight
between 03-06z.

&&

Marine...as of 10:36 am PDT Saturday...high pressure present over
the coastal waters will result in northwest winds today. Winds
decrease through the day and will remain light to moderate into
early next week. Sea conditions gradually improve into Monday
before deteriorating on Tuesday.

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 10-60 nm

&&

$$

Public forecast: CW
aviation/marine: drp

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