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fxus66 kmtr 170104 
afdmtr

Area forecast discussion
National Weather Service San Francisco Bay area
504 PM PST Sat Nov 16 2019

Synopsis...a gradual warming and drying trend will continue through
the remainder of the weekend as high pressure builds over the
region. Cooler conditions will develop on Tuesday as a frontal
boundary sweeps through the region and low pressure develops to our
south. Mainly dry weather conditions are likely to persist with
seasonable temperatures through the second half of the upcoming
week.

&&

Discussion...as of 01:41 PM PST Saturday...low clouds and fog
have mostly dissipated across inland areas of the region by early
this afternoon. However, visible satellite and surface
observations low clouds and fog continue to impact portions of the
coastal areas as well as around the San Francisco Bay reducing
visibility to 1sm or less at times. Look for gradual improvement
in these areas as well through early afternoon as surface
temperatures warm and drier air aloft mix down to the surface.
With this, look for temperatures in the Lower/Middle 60s at the
coast with widespread 70s inland through the remainder of the
afternoon.

Currently expecting less widespread cloud cover and/or fog tonight
as boundary layer conditions dry out a bit in response to the
mid/upper level ridge aloft. In addition, daytime temperatures will
warm a bit on Sunday with more widespread 80s across the interior
and 70s near the coast. These values will be as much as 10 to 15
degrees above seasonal averages. Conditions may only cool slightly
on Monday, most notably at the cast, as the aforementioned ridge
begins to weaken ahead of an approaching upper level trough.

More widespread cooling is forecast by Tuesday lasting into midweek
as an upper level trough over the Pacific northwest drops southward
over California. The forecast models generally agree this system
will pass through the region with very little to no precipitation at
all. As the system drops southward, it is forecast to develop into a
closed low pressure center near/off of the Southern California
coast. At this point, the system will tap into deeper moisture and
potentially result in widespread precipitation over Southern
California. However, there remain differences in the forecast models
on the exact timing and placement of the aforementioned system.
Thus, confidence remains low at this time. The European model (ecmwf) solution shows
the most Promise for precipitation over the central coast, yet even
the ensembles show only a few hundredths of an inch or so from
Wednesday into Thursday. Periods of dry offshore flow may also
develop in the hills in the Wednesday and Thursday timeframe
resulting in heighten fire weather concerns. This is something that
will be monitored in the coming days.

Seasonably cool temperatures are then likely to persist for late
next week into next weekend with mostly clear/sunny conditions.
Aside from the non-zero chance of precipitation mentioned above, dry
weather conditions are likely for the remainder of the forecast
period.

&&

Aviation...as of 5:04 PM PST Saturday...vlifr-IFR in areas of
fog along the coast from Sonoma County to northern Monterey
County, elsewhere it's VFR. The marine layer is shallow varying
from sea level to 500 feet deep, the marine layer remains
compressed under an amplifying mid to upper level ridge.

The source of fog is due to a very shallow, cooler and moist air
mass arriving over our coastal waters on a northwest wind,
favorable contribution is there as well from chilly sea surface
temperatures. The forecast is overall not far from persistence for
the 00z taf cycle, exception is fog arrival and/or development
times adjusted somewhat later for the Bay area tafs due to the
marine layer more compressed than it was 24 hours ago. Late
morning scattering out of fog is likely Sunday away from the ocean
and bays, however fog patches still could linger much of the day
along the immediate coastline under nearly the same weather
conditions as today. Low to very low confidence on ceiling and
visibility forecasts along the coastline Sunday evening.

Vicinity of ksfo...VFR, west wind near 12 knots until 05z then a
light wind overnight. Forecast is for the redevelopment of fog
beginning by 09z with tempo vlifr-LIFR 12z-16z Sunday. Cirrus
clouds at present are forecast to clear up later this evening into
Sunday morning which supports improving radiational cooling and
bringing the air closer to saturation and fog development.

Sfo bridge approach...similar to ksfo.

Monterey Bay terminals...it's a wide range of weather varying from
vlifr in fog on the beaches to nearby areas to VFR in milder weather
not far from the Bay. Overall conditions favor a gentle advection
of fog inland on light west-northwest winds to spontaneous development of
patchy fog under longer night-time hours and radiational cooling.
Low confidence on clearing times Sunday, conditions are not
expected to be that much different Sunday as compared to today.

&&

Marine...as of 3:33 PM PST Saturday...areas of breezy northwest
winds will diminish later tonight and Sunday except over the far
northern waters. A relatively large, moderate period northwest
swell will continue through this evening, producing hazardous
conditions for small crafts, then gradually subside. Moderately
strong and gusty northwest winds are forecast to arrive beginning
Monday evening and a larger northwest swell beginning Tuesday
evening.

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 0-10 nm until 9 PM
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm until 9 PM
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 9 PM
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 9 PM
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm until 9 PM
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...rough bar advisory for sf bar until 9 PM

&&

$$

Public forecast: rgass
aviation: canepa
marine: blier

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