Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
652 am PST Wednesday Nov 25 2015
Synopsis...scattered showers will be possible through the morning as
an upper level pushes inland to our northeast. Given the cold air
mass...light snow will be possible in the highest peaks across the
region tonight into Wednesday morning. Dry weather conditions
return for Thanksgiving day...along with continue cooler than
average temperatures that will persist into the upcoming weekend.
Discussion...as of 3:15 am PST Wednesday...fairly active night as
several bands of showers were detected by radar across our County Warning Area. In
general, additional overnight rainfall was on the light side,
although many spots did see brief periods of moderate to heavy
rain. In general, amounts were less than 1/4".
Radar shows a few showers still across the region with most of the
located south of sf Bay. As the day progresses, the showers will
continue to progress to the southeast. Precipitation will come to
an end by the afternoon with most locations expected to pick up
less than 1/10" of additional rainfall.
Dry and cool weather can be expected late today through at least
Saturday. Temperatures will drop to some of our coldest levels of
the season with many inland spots expected to see lows in the 30s
to lower 40s with the coolest readings expected Thursday and
Friday morning. Worth noting that the airmass is not forecast to
be as cool as was projected a couple of days ago. Despite that,
still looks likely that parts of the North Bay will drop to
Model solutions start to greatly diverge by the end of the week
and continuing into at least the middle of next week. GFS/Gem
both bring at least two substantial systems to our area while the
European model (ecmwf) keeps any rain well to our west. In additional, the GFS and
European model (ecmwf) ensemble plots indicates virtually no agreement between the
different solutions. Therefore, only made minor changes to the
grids due to very poor confidence.
Aviation...as of 4:00 am PST Wednesday...satellite image shows
last of the showers moving through the mry Bay area. A few residual
clouds remain which may produce local MVFR ceilings through 16z after
which drier air will clear it out.
Vicinity of ksfo...VFR.
Ksfo bridge approach...a few clouds could produce local MVFR ceilings
Monterey Bay area terminals...ceilings above 3000 feet with isolated
showers through 17z.
Marine...as of 3:20 am PST Wednesday...northwest winds and seas
will decrease today as low pressure over the Great Basin moves
east. High pressure over the eastern Pacific will extend into the
Pacific northwest Thursday and Friday. This will create more of a
north to northeast flow that will last through the weekend.
... Arena to pt Reyes 0-10 nm until 3 PM
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm until 3 PM
Small Craft Advisory...Pigeon pt to pt pinos 0-10 nm until 3 PM
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 PM
Small Craft Advisory...pt Arena to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm
Small Craft Advisory...rough bar advisory for sf bar until 9 am
Public forecast: Bell
aviation: west pi
marine: west pi
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