Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
143 PM PDT Friday may 29 2015
Synopsis...no big weather changes forecast for Saturday with
coastal stratus spreading inland overnight. By Sunday a system
will approach the coast with a slight chance of showers in the far
North Bay. As the system approaches the marine layer will deepen
and cooler weather will return Sunday afternoon with onshore flow.
Seasonable temperatures and continued dry weather forecast Monday
through the middle of next week.
Discussion...as of 1:43 PM PDT Friday...visible satellite imagery
shows that low clouds have cleared from most areas. The exceptions
are most of the San Francisco peninsula as well as the southern
Monterey Bay and Monterey peninsula. These areas are running cooler
than yesterday at this time with readings in the 50s...but
locations farther inland are several degrees warmer...with 60s and
70s. Expect low clouds to spread inland once again tonight as the
marine layer depth remains around 1600 feet and the surface
pressure gradient is strong onshore at 3.1 mb from sfo to SAC.
Little change is expected in the overall weather pattern for
Saturday...but on Sunday an approaching upper level trough will
ramp up the onshore flow and cool temperatures somewhat. There
remains a slight chance of light rain across the far northern
portions of the North Bay Saturday night and Sunday...but the more
likely scenario will be an increased chance of coastal drizzle by Monday
Medium range models keep a zonal flow aloft across northern
California through much of next week. Thus...onshore flow will
keep seasonably cool temperatures across the area. Night and
morning coastal stratus will be the norm for the first week of June.
Aviation...as of 10:55 am PDT Friday...today the marine layer is
behaving much more like it typically does this time of year. The
Fort Ord profiler is indicating that the marine layer is hanging
in at about 1500 feet...typical for this time of year. The visible
satellite image is showing the stratus eroding quickly out the
southern portion of San Francisco Bay which will allow for visuals
shortly. The visible satellite image is also showing Monterey
socked in but there is evidence of an eddie forming in Monterey
Bay which may give some relief from the stratus this afternoon.
Stratus will return to all terminal late this afternoon/early
Vicinity of ksfo...visuals should are in the near future with VFR
anticipated through early evening with broken-ovc012 by
0200z...deteriorating to ovc007 by 0500z. First guess at tomorrows
clear around 1830z. The sea breeze will reach 20 knots this afternoon
with gusts to 25 knots
Confidence is high.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...ksns should become VFR around 1915z
this with kmry remaining IFR ovc007 through at least 2000z at which
point MVFR broken-ovc012 will be possible. An eddy has formed in
Monterey Bay which may allow for VFR at mry this afternoon but
confidence is low at this point. Stratus is expected to return to
ksns by around 0400z. The sea breeze will reach 10 to 15kt this
Confidence is low for kmry.
Confidence is high for ksns.
Marine...as of 01:19 PM PDT Friday...generally light to locally
moderate northwest winds are expected to prevail today...the
strongest winds are expected south of Point Sur and along the
Sonoma coast. Winds are anticipated to decrease on Saturday and
become southerly on Sunday as a low pressure system approaches
from the west. Winds will strengthen out of the north once again
early next week as a thermal trough builds over California.
... Pinos to pt Piedras Blancas 0-10 nm until 11 PM
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm until 11 PM
Small Craft Advisory...sf Bay north of the Bay Bridge until 8 PM
Small Craft Advisory...sf Bay south of the Bay Bridge until 11 PM
Public forecast: Sims
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