Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA

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000
FXUS66 KMTR 190943
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco Bay Area
243 AM PDT Wed Jul 19 2017

.SYNOPSIS...Onshore flow will keep temperatures near seasonable
normals through this week with late night and early morning low
clouds near the coast. A slight warming and drying trend is then
expected by the upcoming weekend.

&&

.DISCUSSION...as of 2:45 AM PDT Tuesday...The marine layer
continues to be shallow with the Bodega Bay and Ft Ord Profilers
showing a depth of around 900 feet. In addition the n-s pressure
gradient has increased meaning there is less stratus into the
North Bay this morning. The result of all this is that stratus
will again be limited to the coast with some clouds spreading
through the Golden Gate into the San Francisco and Oakland
vicinities. Temperatures will be slightly warmer today as the
onshore flow will have more of a northwesterly component. However
temperatures will still be near or slightly above seasonal
normals.

The marine layer should deepen slightly tonight as an upper level
trough off the Washington coast approaches land and pushes the
upper high over the Southwestern US further east. This would
result in more clouds into the SFO Bay Area and slightly cooler
temperatures Thursday.

The upper high will build back over the southwest this weekend as
the upper trough lifts to the northeast. This will bring warmer
temperatures to the area especially inland. At this time we do not
expect the high to be strong enough to produce any significant
heat over our district. Southwesterly flow aloft should keep
monsoonal moisture east of the district.

Medium range models show an upper level trough approaching from
the west which will bring cooling early next week. However medium
range models have been inconsistent so there is low confidence on
the forecast for next week.

&&

.AVIATION...as of 11:28 PM PDT Tuesday for 6Z TAFs...Infrared
satellite shows marine stratus developing and expanding in
coverage off the central coast along Point Reyes, the San
Francisco Peninsula, and parts of the Monterey Peninsula. Expect
this trend to continue overnight as many terminals transition from
VFR to MVFR and possibly IFR. The marine layer is between 1,000
and 1,100 ft deep per the Fort Ord profiler this evening. Expect
the low clouds to mix out by mid/late morning for most locations
on Wednesday.

Vicinity of KSFO...VFR as of the 6Z TAF issuance; however low
clouds are beginning to approach the terminal from the north and
west via the San Bruno Gap. This can be seen on both satellite
and on webcams. Expect the transition to MVFR to occur around 6
to 7Z. Will monitor the progression carefully and amend as
necessary. Skies will clear out by mid/late morning back to VFR.
Breezy west winds will develop by the afternoon hours around 20 kt
with higher gusts likely.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...Stratus has developed along the Monterey
Peninsula but has yet to be reported at KMRY. Expect that to
change around 7 to 8Z with IFR conditions, though it could happen
a bit earlier. IFR conditions at both KSNS and KMRY should
transition back to VFR by mid/late morning.

&&

.MARINE...as of 10:13 PM PDT Tuesday...High pressure over the
eastern Pacific will allow for moderate northwesterly winds to
persist over the waters for most of the week. A more pronounced
southerly swell is expected to return to the waters on Wednesday.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tday...SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Arena to Pt Reyes 0-10 nm
             SCA...Pt Reyes to Pigeon Pt 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm
             SCA...Pt Arena to Pigeon Pt 10-60 nm
             SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm
             SCA...Mry Bay from 9 AM

&&

$$

PUBLIC FORECAST: W Pi
AVIATION: Rowe
MARINE: Rowe


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