Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1052 PM PDT Wednesday Jul 30 2014
Synopsis...the remnant high cloudiness from what used to be Hurricane
Hernan in the tropical eastern Pacific brushed southern Monterey and
San Benito counties tonight. Otherwise a drier middle to upper level
southwest flow has reached the area and will continue into the weekend.
Temperatures should remain very warm inland and cool along the coast.
Cooler air is expected to spread inland later in the weekend and early
next week as the marine layer deepens.
Discussion...as of 9:00 PM PDT Wednesday...as is typical of our
diverse climates in the region highs today ended up ranging from
the middle 60s coastside to the 80s/90s inland valleys...even all the
way up to 110 at Pinnacles today. Visible imagery from this afternoon
showed a few cumulus clouds popping up over southeastern San Benito
County but they quickly diminished as sunset approached.
Appreciable drying was evident on the 00z Oakland upper air sounding
this evening. The precipitable water value dropped from 1.11" this
morning to 0.80" this evening on the Oak sounding. Most of the drying
today was located above the compressed marine layer. The humid feel
in the air may be a little less noticeable in some areas however there
are some locations still reporting dew point temperatures in the upper
50s to near 60. Remnant tropical cyclone high cloudiness from the south
as well as some additional high cloudiness from the west and southwest
will drift in overnight but it's not expected to be moist or unstable
enough to produce any lightning strikes like it did very early this
morning over northernmost Sonoma County. There were one or two
lightning strikes over northernmost Sonoma County early this
morning. Modeled forecast layer humidity for the 700-500 mb level
shows a steady drying over the forecast area Thursday...Friday and
through the weekend. 500 mb heights are not forecast to change all
that much aside from a subtle downward drift in values over the
weekend and early next week as an eastern Pacific trough approaches
the Bay area and central coast.
Going forecast looks good. Forecast updates are not expected this
Aviation...as of 10:50 PM PDT Wednesday...low clouds are
beginning to fill in through coastal gaps and valleys with LIFR
to IFR ceilings currently being reported over select terminals. Light
winds will persist through tonight with slightly stronger winds
expected during the afternoon hours on Thursday.
Vicinity of ksfo...IFR ceilings have filled in over koak. VFR
conditions expected through tonight over ksfo. Clearing
anticipated around 17z Thursday morning. Moderate onshore flow
around 15 knots will ease overnight becoming light.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...LIFR to IFR ceilings will persist
through tonight. Clearing is expected around 17z Thursday
morning. Light to moderate onshore flow will persist through the
Marine...as of 10:38 PM PDT Wednesday...northwesterly flow will
continue across the coastal waters through the week as high
pressure remains over the eastern Pacific. Wind speeds increase
over the northern outer waters late in the week...resulting in
square seas. Elsewhere...generally gentle sea conditions will
... Arena to pt Reyes 10-60 nm from 3 am
Public forecast: canepa
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