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Area forecast discussion 
National Weather Service San Francisco Bay area
534 PM PDT Tuesday may 5 2015

Synopsis...quiet weather conditions will persist into Wednesday
with temperatures running a few degrees below seasonal averages.
There is a slight chance of showers and thunderstorms Thursday
and Friday...mainly over the mountains as an upper level system
moves in from the north. Dry weather conditions and slightly
warmer temperatures return for the upcoming weekend as the system
shifts inland.

&&

Discussion...as of 01:55 PM PDT Tuesday...temperatures across the
region this afternoon are generally running a few to several
degrees above those 24 hours ago as a result of mostly sunny
conditions. While The Fort Ord profiler continues to show a deep
marine layer in place...good mixing allowed most of the cloud
cover to dissipate this afternoon. Give the lingering clouds off
of the San Mateo coast and down the Big Sur coast...it appears
low level clouds will make a return tonight. In addition...there
remains a chance of patchy drizzle overnight into early Wednesday
morning from the San Mateo coast southward.

Little chance is expected for Wednesday as a middle/upper level low
pressure system that pushed inland over British Columbia today
begins to slowly drop southward into the Pacific northwest. This
system will then dig further southward late in the week and bring
cooler temperatures and unsettled conditions to much of the
region. With the middle/upper level low forecast to be centered over
the San Francisco/Monterey Bay region on Thursday...the
atmosphere will become more unstable and the influence of the
marine layer will be disrupted. While the forecast models keep
the best moisture advection over the inland portion of the
state...the increased instability and moisture over our region
will likely result in a slight chance of showers by Thursday
morning. With daytime heating...convection will likely increase
with the potential for afternoon/evening thunderstorms...
especially over the inland hills/mountains. While widespread
rainfall is not expected...cannot rule out brief heavy downpour
associated with any thunderstorms that develop on Thursday.
Lingering showers will be possible early Friday over southern
Monterey and San Benito counties before the middle/upper level low
ejects eastward.

With the aforementioned system exiting the region...a middle/upper
level ridge axis will build inland resulting in dry weather
conditions and warmer temperatures for Saturday and Sunday. With
the next middle/upper level system projected to move inland to our
north early next week...the models maintain dry weather
conditions along with temperatures near seasonal averages for at
least the first half of next week. In other words...typical middle-
may weather conditions will be likely for much of next week.

&&

Aviation...as of 5:00 PM PDT Tuesday...a strong 5.4 mb northerly
gradient from acv-sfo will keep area terminals free of stratus
through this evening. Patchy low clouds are expected to return
overnight to Monterey Bay area terminals but elsewhere should
remain mostly clear. Onshore flow will persist through the period
with moderate and locally gusty winds through the evening hours.
Light southwesterly winds anticipated overnight.

Vicinity of ksfo...VFR conditions expected through the forecast
period. Strong and gusty onshore flow expected through this
evening with sustained wind speeds of 15 to 20 knots and gust to
near 30 knots possible.

Sfo bridge approach...similar to ksfo.

Monterey Bay area terminals...VFR conditions expected through
early evening. MVFR ceilings anticipated to return between 02z-04z
tonight. Moderate and locally gusty winds will persist with
sustained winds around 15 knots with gust over 20 knots possible. Winds
will ease overnight with clearing anticipated around 18z-19z
Wednesday.

&&

Marine...as of 11:13 am PDT Tuesday...high pressure in the
eastern Pacific will increase northerly winds over the coastal
waters through the week. The strongest winds are expected
beginning later today and into tomorrow. Gale force winds will be
possible over the outer waters north of Pigeon Point later today.
The strong winds will produce hazardous conditions with steep wind
waves and fresh swell. Wind and waves will gradually ease late in
the week.

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm
glw...pt Arena to pt Reyes 10-60 nm
glw...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...Monterey Bay until 3 am
Small Craft Advisory...sf Bay north of the Bay Bridge until 9 PM
Small Craft Advisory...sf Bay south of the Bay Bridge until 9 PM

&&

$$

Public forecast: rgass
aviation: CW
marine: drp

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