Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Francisco Bay area
1102 PM PDT sun Jul 24 2016
Synopsis...temperatures will warm up Tuesday and Wednesday as
high pressure strengthens over the area, with cooling once again
in the forecast this weekend as a weak low pressure disturbance
moves into the Pacific northwest.
Discussion...as of 9:00 PM PDT Sunday...an upper level high
remains centered over The Four Corners area with light WSW flow
aloft over the area. The marine layer deepened from about 800 feet
last night to 1200 feet this afternoon. High temperatures were
several degrees cooler around sfo and mry Bay today but little
Not much change is expected Monday but a shift in the winds above
the marine layer to south to southwest is expected Monday. This
could bring more smoke aloft from the soberantes fire into the
mry Bay area. Warming is expected Tuesday and Wednesday as the
upper high shifts westward. This will put the area under a light
southeast flow aloft with the possibility of some mid and high level
clouds getting into the southern part of the County Warning Area. There does not
appear to be sufficient moisture or instability for convective
The upper high will remain over the southwest through the week.
Models indicate increasing moisture in Southern California and the
southern sierras but keeps moisture out of our cwa. Temperatures
will continue to run above normal until the weekend when an upper
trough off the Pacific northwest brings a little cooling.
Aviation...as of 11:01 PM PDT Sunday...the marine layer continues
to trend deeper this evening, presently 1,500 feet deep over the
Bay area to approx 1,700 feet deep north central coast. Stronger
as well as moist northwest flow just south and southwest of Point Arena
is located next to lighter west-northwest flow over the inner waters
spinning up a nearly stationary cyclonic lower level circulation
within the stratus/fog which will likely persist into Monday.
Despite a robust onshore gradient driven wind the inland
stratus/fog intrusion has been minimal over the Bay area and a bit
more pronounced over the north central coast this evening likely
due to this circulation developing as well as much drier lower levels
mixing into the marine layer along the eastern edge. Complicating
things a bit more is 1c-2c cooling at the 925 mb level tonight and
Monday morning which may tend to weaken and lift marine inversions
higher, possibly leading to an early scattering of stratus and fog
Vicinity of ksfo...VFR. Tempo IFR cig 11z-15z Monday with IFR cig
til 17z. VFR from late Monday morning to the evening.
Sfo bridge approach...similar to ksfo.
Monterey Bay terminals...IFR cigs tonight and Monday morning. Fog,
haze, and wildfire smoke resulting in restrictions to the visibilities.
Marine...as of 9:23 PM PDT Sunday...high pressure over the eastern
Pacific will maintain northwesterly winds over the coastal waters
this week. Gusty onshore winds will persist tonight over the San
Francisco Bay northward of the Bay Bridge to the West Delta.
... Arena to Pigeon pt 10-60 nm
Small Craft Advisory...pt Arena to pt Reyes 0-10 nm
Small Craft Advisory...Pigeon pt to pt Piedras Blancas 10-60 nm
Small Craft Advisory...sf Bay until 3 am
Small Craft Advisory...pt Reyes to Pigeon pt 0-10 nm until 3 am
Public forecast: west pi
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