626
FXUS66 KMTR 080809
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
109 AM PDT Sun Sep 8 2024

...New SYNOPSIS, SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 108 AM PDT Sun Sep 8 2024

A few more days of above average temperatures region-wide before a
cool down occurs on Tuesday in response to an upper level trough
digging into the Pacific Northwest.

&&

.SHORT TERM...
(Today and tonight)
Issued at 108 AM PDT Sun Sep 8 2024

Only subtle cooling will occur this afternoon with high temperatures
forecast to be in the mid 80`s to mid 90`s across the interior, 70`s
and 80`s around the Bay Shoreline, and 60`s and 70`s near the coast.
The warmest interior parts of the Central Coast will warm between
100 and 105 degrees. This slight "cool down" is in response to a
mid/upper level through impacting the northern half of the region.

Tonight, the marine layer will deepen slightly with further inland
penetration of low stratus into the coastal adjacent valleys. Patchy
fog is also expected once again over night, especially near the
coast and in the North Bay valleys. Temperatures will drop into the
low to upper 50`s across much of the region, near 60 degrees across
the Santa Clara Valley and interior East Bay, and 60`s to upper 70`s
in the higher peaks of the Central Coast.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 108 AM PDT Sun Sep 8 2024

Monday will cool down by a few degrees, especially across the
interior as 500mb heights lower and the airmass aloft cools.
However, temperatures will remain above seasonal averages again on
Monday. Onshore flow will persists and deepen the marine layer to
around 1,500 feet in depth by Monday night.

A more pronounced upper level trough will drop into the Pacific
Northwest by Tuesday and Wednesday. This will drop temperatures back
to near or below seasonal averages with mid 70`s to mid 80`s across
the interior and more widespread 60`s at the coast. Some offshore
flow is possible as the low shifts across the Intermountain West on
Thursday, especially in the higher elevations. However, it does not
appear to be a great setup for stronger offshore winds.

&&

.AVIATION...
(06Z TAFS)
Issued at 1112 PM PDT Sat Sep 7 2024

Stratus is filling in along the coastline and starting to push
inland. IFR to LIFR CIGs are expected overnight with elevated fog
potential across the North Bay and Central Coast. Stratus may remain
patchy into the early morning before filling in more consistently
around 10-12Z. Stratus is expected to clear by mid to late morning
with an early return of stratus possible in the mid to late evening.
Aside from the North Bay where winds are more southerly to
southwesterly, winds generally stay out of the northwest. Winds are
expected to weaken at all stations overnight before strengthening
and becoming moderate again tomorrow afternoon/evening.

Vicinity of SFO...Night fog shows stratus moving through the San
Bruno gap with few to scattered low level clouds currently reaching
SFO. Stratus is expected to fill in more consistently around 08Z as
stratus pushes inland. IFR CIGs are currently expected but given the
current observations showing few clouds around 300 ft cannot fully
rule out the possibility of LIFR CIGs developing later tonight. The
RAP and HRRR both suggest 8-10Z as the most likely time for stratus
arrival. Any stratus that does develop will persist through late
tomorrow morning with VFR expected to continue through the
afternoon/evening. Winds generally stay out of the west to northwest
with breezier conditions and gusts up to 25 knots possible during
the day.

SFO Bridge Approach...Similar to SFO but stratus may take longer to
fill in over the bay compared to at SFO which may allow VFR
conditions to persist for longer overnight on the approach compared
to at the airport.

Monterey Bay Terminals...Stratus is currently filling in over the
Monterey Bay Region with LIFR CIGs to reach MRY and SNS early this
morning. An otter eddy looks to be developing which may keep stratus
coverage patchy for the next few hours before stratus moves in more
consistently. Similar to the last few nights, elevated fog potential
continues with visibilities down to 1/2SM possible after stratus
moves in. Winds generally stay out of the northwest but weak
offshore flow may develop overnight as winds become more light and
variable. Winds strengthen and become more moderate during the day
at SNS but are expected to stay fairly light through the TAF period
at MRY.

&&

.MARINE...
(Tonight through next Friday)
Issued at 1112 PM PDT Sat Sep 7 2024

Moderate to breezy north and northwest winds continue through the
weekend with occasional gusty winds over the southern waters.
Northwest winds strengthen and wave heights increase over the
California coastal waters ahead of an incoming low pressure system
by the middle of next week with unsettled conditions persisting
through the end of the week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa/Kennedy
MARINE...Canepa

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