Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
838 am PDT Thursday Aug 28 2014
Synopsis...above average temperatures and dry weather conditions
will persist through the remainder of the week due to high
pressure along the West Coast. Afternoon temperatures then trend
slightly cooler through Labor Day as the ridge weakens and an
upper level trough impacts northern California.
Discussion...as of 8:35 am PDT Thursday...nice satellite loop
this morning with Tropical Storm Marie clearly defined centered
around 900 miles SW of San Francisco. Also based on satellite and
observations, minor forecast update issued earlier to increase
cloud cover along with fog through the Salinas valley. Otherwise,
main story for today through at least most of next week is for
quiet weather with clouds at the coast for the overnight hours and
sunshine at most spots during the day. Temperatures will be seasonable
with highs generally 60s and 70s at the coast with upper 70s to
lower 90s inland.
Previous discussion...the return of a better defined marine
layer has allowed coastal clouds to develop and push inland this
morning. This has kept temperatures across the region in the
middle/upper 50s to lower 60s. However...cloud cover should quickly
burn-off by late morning and give way to mostly sunny skies inland
and warm afternoon temperatures. Overall...most locations will be
a few to several degrees above seasonal averages as high pressure
aloft continues to impact the region.
Little change is expected on Friday as the middle/upper level ridge
continues to influence the region. The tail end of an upper level
trough will then drop southward across northern California late
Friday into Saturday and bring temperatures back to near seasonal
averages. During this time...the marine layer will likely deepen
and increase the amount of overnight/early morning coastal clouds
and patchy fog throughout the weekend. In addition...cannot rule
out the possibility of patchy drizzle along coastal locations this
Seasonal temperatures and dry weather conditions are likely to
persist on Labor Day and through the middle of next week as the
region remains under a dry northwest flow aloft. Toward the end of
the extended period...medium range forecast models are indicating
a deeper middle/upper level trough will impact the region late next
week. At this time...this system appears to be a dry one and would
most likely cool temperatures to below average region wide.
Aviation...as of 4:30 am PDT Thursday...low clouds are spreading
over the sfo Bay area but a hole in the stratus remains from sfo
to the San Mateo bridge. Still a question of whether ceilings will
fill in this area but in any case ceilings will impact the approach
through 17z possibly as late as 18z.
Vicinity of ksfo...brief IFR ceilings are possible over the Airport
through 16z. Increasing onshore flow will cause west to northwest
winds 18-20 knots after 20z.
Ksfo bridge approach...IFR ceilings impacting the approach through 17z
and possibly to 18z.
Monterey Bay area terminals...IFR ceilings through 18z.
Marine...as of 04:24 am PDT Thursday...latest buoys report swell
5-7 feet at 14-15 second period. Swell direction is from 150-170
degrees. A swell from this direction will bring hazardous beach
conditions to Southern California but not so much our coastal
waters. Swell direction is expected to switch to southwest this
weekend but swell heights will subside to around 3-4 feet which is
just below beach hazards criteria. Therefore a beach hazard
statement will not be issued but caution is still advised when
venturing near the ocean this weekend.
Public forecast: Bell/rgass
aviation/marine: west pi
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