Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
348 am PDT Monday may 25 2015
Synopsis...cooler than normal weather...along with widespread
night and morning low clouds...will continue through Tuesday. Warmer
conditions are expected during the second half of the
week...especially for inland areas. However...coastal areas will
remain seasonably cool as onshore flow persists.
Discussion...as of 3:45 am PDT Monday...cooler than normal
weather conditions...which have persisted across the San Francisco
Bay area and Monterey Bay area for the past three weeks...will
continue for at least a few more days. Although an upper ridge has
developed offshore along 135w...an upper low is settling into the
Pacific northwest and helping to maintain a deep marine layer across our area.
And...cool marine air is flowing well inland thanks to a persistent
Little change is expected through Tuesday. Widespread night and
morning low clouds will persist...along with patchy drizzle near
the ocean. Daytime temperatures will remain in the upper 50s along
the immediate coast where little or no afternoon sun is expected.
Afternoon clearing is expected inland...but high temperatures will
continue to be at least five degrees below normal in most
The models have been consistent in moving the upper ridge to the
east by midweek...with the ridge axis position forecast to be over
the West Coast by late Thursday. As the ridge builds over California
during the second half of the week...look for the marine layer to
be compressed and temperatures to rise...especially inland...as
the airmass warms aloft and marine air influence dwindles. Inland
temperatures are forecast to rise a few degrees above normal by
Thursday and Friday when 80s will finally return to locations like
Livermore...Gilroy and Calistoga. A shallow...but
persistent...marine layer along with continued onshore flow will
mean the coastal strip will see much less warming compared to
inland areas later this week.
Warm conditions will continue into at least the first part of next
weekend. But the ridge is forecast to move eastward over the
weekend as a trough approaches the West Coast. This will mean
cooler conditions by Sunday.
Other than patchy late night and morning coastal drizzle the next
few days...no precipitation is forecast through next weekend.
Aviation...as of 11:00 PM PDT Sunday...for 06z tafs. Stratus has
filled in across all terminals. Partial clearing is expected again
Monday. Ksfo and koak along with Monterey Bay terminals are not
expected to clear but rather will see ceilings lift temporarily in
the afternoon. Light to locally moderate onshore flow will
continue through tonight.
Vicinity of ksfo...MVFR ceilings will lower to IFR overnight. Ceilings
will lift after 20z Monday but area terminals are not expected to
clear. Light to locally moderate onshore flow will prevail.
Ksfo bridge approach...IFR ceilings around 1000 feet expected overnight.
Ceilings will clear from the south Monday morning but area terminals
will remain overcast around 1500 feet through the afternoon.
Monterey Bay area terminals...IFR ceilings will persist through the
tonight. Ceilings will lift after 18z-19z Monday but area terminals are
not expected to clear. Light onshore flow will prevail.
Marine...as of 3:08 am PDT Monday...northwesterly winds will
continue across the coastal waters today then gradually east into
Tuesday with fairly light seas. Some slightly stronger northwest
winds will return by late in the week but in general expect a
prolonged period of generally light wind and seas.
... Arena to pt Reyes 10-60 nm until 3 am
Small Craft Advisory...sf Bay north of the Bay Bridge from noon
Public forecast: dykema
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