Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
320 am PDT Friday may 22 2015
Synopsis...a low pressure trough over the West Coast will keep cooler
than normal weather for the area along with the possibility for light
showers through Friday. Slight warming can be expected over the
weekend as the low moves out of the area.
Discussion...as of 3:20 am PDT Friday...the upper level low that
brought some light showers to the area yesterday has now moved to
the south and is currently off the Southern California coast. Some
wrap-around moisture is keeping shower activity going in the northern
Sierra as well as over the San Luis Obispo/Kern County border. A
slight chance of light rain showers is possible again today over
portions of the district today...and into this evening across the
far eastern sections. Highs today are expected to be similar to
those on Thursday...cool with lower 60s at the coast to the 70s
The upper low is prognosticated to move over northern Arizona by late
Friday night...and shower chances across our district will
diminish. There may be some patchy coastal drizzle Saturday
morning but that will be it.
A slight warming trend is indicated beginning Saturday and
continuing into early next week as weak high pressure builds along
the coast. The marine layer will become even more compressed
allowing areas away from the coast to warm back up to near normal
values. Medium range models indicate continued dry conditions
with near normal temperatures through next week.
Aviation...as of 9:00 PM PDT Thursday...there was local clearing
of the low clouds around sfo early this evening but clouds are
expected to fill back in overnight as a deep moist layer is over
the area. Ceilings will stay through a good part of the day Friday as
an upper level low moves inland over Southern California.
Vicinity of ksfo...MVFR ceilings with possible clearing late Friday afternoon.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...MVFR ceilings through Friday. Possible
clearing late Friday afternoon.
Marine...as of 02:07 am PDT Friday...generally light winds will
prevail today but are expected to increase out of the northwest
this evening as the surface pressure gradient increases. The
increasing winds will result in deteriorating sea conditions.
Winds are anticipated to stay up this weekend but the forecast
calls for decreasing winds and improving sea conditions for
... Arena to pt Reyes 10-60 nm from 5 PM
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm from 7 PM
Small Craft Advisory...sf Bay north of the Bay Bridge from 2 PM
Public forecast: Sims
aviation: west pi
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