Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1050 am PDT Wednesday may 27 2015
Synopsis...a modest warming trend is expected to begin today
persisting through Saturday...most apparent inland as high
pressure builds along the coast. Another cooling trend will start
on Sunday and continue into early next week as a weak Pacific low
approaches the coast. Mostly dry conditions will continue into
early next week.
Discussion...as of 08:56 am PDT Wednesday...a deep marine layer
around 3000 feet has once again resulted in widespread low clouds
over the region this morning. Expecting clouds to continue to
burn-off through late morning/early afternoon with temperatures
warming into the 70s to lower 80s inland. Meanwhile...coastal
locations will likely remain in the 60s with clouds likely to
persist just off of the coastline. With this...no changes are
needed to the ongoing forecast at this time.
Previous discussion...as of 3:00 am PDT Wednesday...after multiple
days of widespread clouds and cooler than normal temperatures
across the board today will be the start of a transition to more
typical late may weather. Current satellite product shows clouds
across a good portion of our area...however Worth noting that in
some areas it has not filed in as much as previous nights. In
addition...the surface flow which has been moderate to robust from
the west has switched to now being more from the northwest as the
north to south piece has increased by more than 2.5 mb over the
past 24 hours. Relative humidity values are almost all drier compared to
yesterday as well. Therefore...expectations are for a quicker
burn-off today with a better chance for coastal spots to see more
sunshine. Temperatures will also increase a modest amount today
particularly for inland spots. Highs will range from 60s at the
coast to 70s and lower 80s inland.
Synoptically a ridge of high pressure will build overhead with
the ridge axis expected to be near our area Friday and Saturday.
This will coincide with 850 mb temperatures hitting their warmest
readings for the week...19 to 20c. Inland temperatures will return back
to above normal levels with event a few lower 90s possible. Highs
will only see minor increases at most coastal spots as the cool
sea surface temperatures combine with afternoon sea breezes. Overall
temperature gradients will be normal for our area going into
Summer -- upper 50s at the coolest ocean spots with lower 90s in
southern Monterey County.
Temperatures will start to cool on Sunday as an upper level low
moves into the pacnw/norcal region. Models bring the southern
extent of moisture into the North Bay so added a slight chance of
rain for Sunday. The low is expected to quickly eject to the
northeast with another ridge forecast to build in behind it.
Warmer than normal temperatures are expected for the second half
of next week along with mostly dry conditions. &&
Aviation...as of 10:50 am PDT Wednesday...a deep marine layer of
around 3000 feet continues over the district. Widespread MVFR ceilings
will begin to then mix out between 19-20z depending on distance from
coast. Deeper marine layer returns later this evening. Onshore
flow through the period.
Vicinity of ksfo...sfo is on the edge of the cloud bank with
occasional MVFR ceilings possible through 19z. Onshore flow 10-20 knots
through the afternoon. MVFR ceilings return 04-05z Thursday.
Ksfo bridge approach...similar to ksfo.
Monterey Bay area terminals...MVFR ceilings through 21z...then VFR until
Marine...as of 8:27 am PDT Wednesday...high pressure over the
central coast will lead to light northwest winds and gentle seas
today. Northwest winds are forecast to increase this evening with
the strongest winds along the Big Sur coastline through the
remainder of the week.
Public forecast: rgass
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