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Area forecast discussion 
National Weather Service San Francisco Bay area
217 PM PDT Tuesday Sep 30 2014

Synopsis...building high pressure over the region will result in
a drying and warming trend through late week. With this...daytime
temperatures will be as much as 10 to 15 degrees above seasonal
averages by late week.

&&

Discussion...as of 02:15 PM PDT Tuesday...generally quiet weather
conditions persist in the short-term as a ridge of high pressure
continues to build over the eastern Pacific. This will result in a
drying and warming trend of the air mass aloft through midweek. In
addition...this pattern will begin to dry out the boundary layer
and diminish the amount of overnight/early morning cloud cover.
May still see patchy clouds tonight...yet mostly clear skies can
be expected region-wide by Wednesday.

The strong ridge is then forecast to be positioned along the West
Coast Thursday through the first half of the weekend. During this
period...the 850 mb temperatures are expected to approach or
exceed 20c and the surface thermal trough is forecast to shift to
the coast. This will cause offshore flow to develop across inland
areas and bring very warm temperatures all the way to the
coastline by Thursday and Friday. At this time...the warmest
daytime temperatures are forecast for Friday...when middle/upper 80s
to lower 90s will impact the urban areas of the San Francisco Bay
area. Locations along the central coast will also warm into the
upper 80s to lower 90s by Friday afternoon with temperatures in
the upper 90s to near 100 further inland and higher in elevation.

The offshore flow over inland areas is then expected to weaken
slightly and allow for temperatures to fall a few degrees on
Saturday. However...temperatures will remain well above seasonal
averages. While the ridge remains over the region through early
next week...weak onshore flow will likely return along the coast
by Sunday and cool temperatures further...especially near the
coastline. Meanwhile...above average temperatures and dry weather
conditions will persist through early next week.

&&

Fire weather...as of 2:15 PM PDT Tuesday...offshore flow will
develop over the region tonight and early Wednesday. This is a
typical pattern where winds will be strongest over the north and East Bay
hills right around sunrise Wednesday morning. Would not be
surprised if gusts up to 40 miles per hour were observed over the highest
peaks. Initially tonight...humidities will be high but rapidly
plummet as the offshore flow Cranks up. Winds will gradually
weaken through day Wednesday allowing for further drying in the
boundary layer. Offshore flow continues into the weekend producing
poor night time recoveries...but winds will be light. Despite the
offshore winds and poor recoveries a red flag warning will not be
issued due to the wet fuels. The recent rains have left fine fuels
moist for this time of year. It will take some time to dry things
back out. Fuels may return to critical levels later this week.
None the less...a prolonged period of hot and dry conditions are
expected middle week lasting into the weekend. Stay tuned.

&&

Aviation...as of 10:30 am PDT Tuesday...patchy low clouds filled
in across sf Bay so burn off taking a bit longer this morning. Northwest
flow reinforcing clouds across mry Bay through noon. Otherwise VFR.
Light sea breeze this afternoon. Northerly gradient should prevent
low cloud development tonight except southern mry Bay during the
evening which would likely clear out later.

Vicinity of ksfo...MVFR ceilings to clear shortly. Then VFR through
Wednesday.

Ksfo bridge approach...similar to ksfo.

Monterey Bay area terminals...northwest flow bringing more stratus into
mry Bay. Sns to stay VFR with MVFR possible through around noon mry.
Ceilings look to come back briefly tonight before offshore flow and
the increasing north gradient clear skies once again.

&&

Climate...record high temperatures for Wednesday through Friday
(10/1 to 10/3) along with the most recent date it occurred.

Sf Bay area
location.................10/1...........10/2............10/3...
Kentfield................97/2012.......100/2012.........99/2012
San Rafael..............104/1980.......106/1980........105/1980
Napa....................106/1980.......102/1980........103/1917
San Francisco............97/1980........96/1980.........97/1985
sfo Airport..............97/1980........96/1980.........94/1985
Oakland (downtown)......103/1980.......103/1980........100/1985
Oakland Airport..........94/1952........98/1980.........95/1985
Richmond.................99/1980.......100/1980.........97/2012
Livermore...............102/1952.......106/1980........106/1980
Moffett field............93/1980........95/2012.........97/1985
San Jose.................97/1980........96/2012.........97/1985
Gilroy..................104/2001.......107/1980........106/1980

Monterey Bay area
location.................10/1...........10/2............10/3...
Monterey................103/1980.......101/1980.........96/1985
Santa Cruz..............102/1965.......102/1980........102/1980
Salinas.................104/1980.......100/1980.........97/1985
Salinas Airport.........105/1980.......103/1980.........99/1985
King City...............109/1980.......107/1980........102/1980

&&

Marine...as of 08:59 am PDT Tuesday...high pressure is
strengthening off the northern California coast. This will bring
moderate northwest winds with strongest winds over the northern
outer waters. Winds will decrease Wednesday night and Thursday as
high pressure builds over the Great Basin and brings offshore flow
to the area.

&&

Mtr watches/warnings/advisories...
... Arena to pt Reyes 10-60 nm
Small Craft Advisory...pt Reyes to Pigeon pt 10-60 nm
Small Craft Advisory...Pigeon pt to pt pinos 10-60 nm
Small Craft Advisory...pt pinos to pt Piedras Blancas 10-60 nm
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm until 3 am
Small Craft Advisory...pt pinos to pt Piedras Blancas 0-10 nm until 3 am

&&

$$

Public forecast: rgass
aviation/marine: ac
climate: Bell
fire weather: mm

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