Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service San Francisco Bay area
906 am PDT Thursday Apr 17 2014
Synopsis...dry conditions will continue through the weekend.
Moderate onshore flow will keep coastal areas cool...along with
areas of night and morning low clouds and fog. Temperatures for
inland areas will cool somewhat...but mostly remain a bit warmer
than normal. A low pressure system will arrive late Monday into
Tuesday...bringing a chance of showers as well as cooler
Discussion...as of 9:06 am PDT Thursday...satellite imagery shows
a large batch of middle and high clouds streaming northward into
Monterey and San Benito County from an upper low center located
west of Baja California California. Also...there are low clouds along the
coastline and locally inland...mainly over Monterey and into
western San Mateo County. An upper level trough is approaching
the West Coast from the north. This is expected to be a dry
front...though...with the main effect being a brief increase in
northwesterly winds as it moves through this evening and
overnight. Winds will be gusty over the coastal waters...but also
over the coastline...mainly from coastal Marin County south
through the San Francisco peninsula.
Weak high pressure will build back over area during the weekend
which will help to boost high temperatures back to above normal.
Nighttime low clouds and fog look more likely during that time
especially at the coast. The ridge will be replaced by zonal flow
on Monday as a long wave trough approaches the coast. On Tuesday
the trough axis is prognosticated to move inland and a slight chance of
showers is possible. There will also be a slight chance of
thunderstorms mainly across the north and East Bay. Highs will
generally just be in the 50s and 60s with lows Tuesday night in
the 40s for urban spots and just 30s for the mountains and hills.
There is less agreement amongst the medium range models for the
remainder of next week with some indications for another trough
passage by the end of the week.
Aviation...as of 4:45 am PDT Thursday...patchy stratus starting
to form along the San Mateo coast and in mry Bay. Dry airmass
over the area will keep VFR conditions in the sfo Bay area for one
more day. East-west gradient will be increasing during the day while the
north-S gradient remains strong. This will result in breezy conditions
in the afternoon.
Vicinity of ksfo...VFR. West winds gusting to 25 knots after 20z.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...stratus over mry Bay area is thin
and patchy this morning. Thus early clearing is expected with ceilings
breaking up by 16z.
Marine...as of 4:45 am PDT Thursday...latest ascat scatterometer
shows winds 20-30 knot winds along the coast but no indications of
gale force winds. Therefore will let the gale warnings expire.
However Small Craft Advisory will remain over all the coastal
waters through Friday night. The prolonged period of steady wind
will result in large steep seas even outside of the areas of
... 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...pt 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
Small Craft Advisory...San Francisco Bay south of the Bay Bridge from 1 PM
Public forecast: Sims
aviation: west pi
marine: west pi
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