Scientific Forecaster Discussion
fxus66 kmtr 281143
Area forecast discussion
National Weather Service San Francisco Bay area
443 am PDT Wed Jun 28 2017
Synopsis...marine air and stratus filtering inland on onshore winds
will persist causing near to slightly cooler than normal temperatures
today. Somewhat warmer temperatures will develop Thursday and Friday.
Except for patchy coastal drizzle, dry weather will persist over the
next 7 days. Night and morning coastal clouds will be followed by sunny
Discussion...as of 3:37 am PDT Wednesday...it's a fairly typical
Summer stratus and fog pattern over the Bay area and north central
coast this morning. The sfo-SAC pressure gradient is 2.6 mb resulting
in onshore winds carrying ocean based stratus inland this morning in
a marine layer 1500-2000 feet deep. In addition to patchy fog, patchy
light drizzle has also been reported along the immediate coastline
since late last evening.
An upper level geopotential height ridge over the eastern Pacific will
gradually advance toward the area late this week. Nearly stationary
lower to mid level thermal ridging over California will tend to
merge with the height ridge steadily strengthening the height ridge
as well as marine inversions through late week, and likely compress
inversions causing more favorable conditions for fog. Diurnal
warming contrasts between land and ocean will strengthen the
afternoon and evening sea-breezes causing stratus and fog to move
inland each night and morning; patchy dense fog may become more
favorable at times, mainly night-time and morning, from late week
into this weekend.
Aviation...as of 04:35 am PDT Wednesday...for 12z tafs. It's
Summer and the marine layer is strong. Low clouds filled back in
overnight at all terminals. Better defined layer than 24 hours ago
with higher cig heights. Cigs range from IFR to MVFR. Will follow
a more Standard burnoff 17-18z. VFR this afternoon with lingering
cigs along the coast. Cigs return tonight.
Vicinity of ksfo...MVFR cigs through 17-18z. Sfo currently showing
only a broken at 3k ft, but will put low cig in taf as it should
lower by sunrise. Gusty winds up to 25 kt this afternoon.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...IFR cigs through 17-18z, but fog seems
less likely. VFR this afternoon.
Marine...as of 2:13 am PDT Wednesday...moderate to locally strong
northerly winds will prevail along the central coast as high pressure
builds off the coast. Gusty winds will result in hazardous conditions
with steep wind waves and fresh swell.
... Reyes to Pigeon pt 0-10 nm from 3 PM
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm from 3 PM
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm from 3 PM
Small Craft Advisory...sf Bay from 11 am
Public forecast: canepa
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