FXUS66 KMTR 300558
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1058 PM PDT Sat Aug 29 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1240 PM PDT Sat Aug 29 2026
- Another beautiful day Sunday
- Cooler weather this week
&&
.SHORT TERM...
Issued at 1053 PM PDT Sat Aug 29 2026
(Tonight through Monday)
Saturday was a beautiful sunny day across the Bay Area and Central
Coast and we'll get more of the same on Sunday. The marine layer
stratus fully evaporated by noon as a much direr air mass moved in
from the north. The 00Z weather balloon measured the precipitable
water at 0.58", which is around the 10th percentile for this time of
year. With unimpeded radiative cooling, marine layer stratus is
starting to reform, with Half Moon Bay recording the first clouds
overhead this evening. Coastal areas south of the Golden Gate
will likely see the stratus come back before the sun rises Sunday
morning. Inland valleys are more of a toss-up. The marine layer is
currently 1,600' deep and will gradually expand over the next 24
hours. Any clouds that form will likely clear by midday with a
mild, breezy, and clear afternoon.
Marine layer stratus should be much better organized by Monday
morning. The depth will likely be around 2,000' by then, with less
chance of clearing along the coast. As a short wave trough moves
through, temperatures will also be around 5 degrees cooler than the
weekend with a stronger onshore breeze in the afternoon.
&&
.LONG TERM...
Issued at 1053 PM PDT Sat Aug 29 2026
(Monday night through next Saturday)
As the troughing pattern continues, the 850 mb temperature will
bottom out around 6-10 C on Tuesday. That's about as low as it gets
this time of year and more like a normal November day. High
temperatures will be in the 60s and 70s with the typical marine
layer stratus in the morning. The troughing pattern will deepen and
a cut-off low will bring some early rain to the Pacific Northwest
later this week. There is a chance for some light rain to make it as
far south as the North Bay starting Tuesday. The ECMWF ensemble mean
shows a few hundredths at Santa Rosa from Tuesday through Friday,
with a 10% chance of reaching 1/2". The probability drops quickly
further south outside of some marine layer drizzle along the
coast. This cut-off low now looks like it will linger near
Northern California into the weekend. If so, this low pressure
breaks up the normal subtropical high and opens the door for
tropical cyclones and the associated moisture to recurve to the
north rather than being held in the tropical latitudes. While it's
too early to say if that will happen, the persistent troughing
pattern looks like it may keep the door open into next week.
&&
.AVIATION...
(06Z TAFS)
Issued at 918 PM PDT Sat Aug 29 2026
VFR prevails across the forecast area except for a newly
developing patch of stratus /MVFR-IFR/ vicinity KHAF Airport and
wildfire smoke reducing slant range and surface visibilities in
southern Monterey County. A well established deep layered mid-
latitude wind flow returned last night and today which thoroughly
dried out the atmosphere at and above the lower level subsidence
inversion (temperature inversion based at 1600 feet per latest 00z
Oakland upper air sounding). Earlier today this drying combined
with surface heating and fully mixed out even lingering coastal
stratus and fog. Independent of the 500 mb pattern, thermal ridging
remains between 925 mb and 700 mb tonight and Sunday. Model forecasts
show stratus and fog returning tonight and Sunday morning, though
it'll take time for redevelopment. A dry atmosphere above the
lower level temperature inversion will result in radiative cooling
tonight to daybreak Sunday. This and any near surface cool air
advection and gentle upslope cooling will help coastal stratus
and fog redevelopment. Most inland locations likely stay VFR
tonight and Sunday.
Vicinity of SFO...VFR except tempo stratus /IFR/ 11z-15z Sunday.
Stratus /IFR/ then returns early Monday morning. West wind 16 to
25 knots until 07z this evening, then west wind 10 knots tonight
and Sunday morning. West wind 15 to 22 knots Sunday afternoon to
mid evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR. Radiative cooling combining with
gentle upslope cooling will result in stratus and fog/mist /IFR-
LIFR/ redevelopment tonight to daybreak Sunday. Tempo stratus and
fog/mist /LIFR/ forecast 09z-14z, prevailing LIFR until late
Sunday morning. Stratus, fog/mist mix out to VFR 17z Sunday. Stratus
/IFR/ redevelops Sunday night. Winds mainly west to northwest 5 to
15 knots.
&&
.MARINE...
(Tonight through next Friday)
Issued at 909 PM PDT Sat Aug 29 2026
Fresh northwest breezes with strong to near gale force gusts
steadily diminish to gentle by Monday. A long period southerly
swell around 17 to 18 seconds persists into Sunday. Wind driven
rough seas gradually subside back to moderate by the beginning of
the work week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Mry Bay-Pigeon Pt
to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 9 PM PDT Sunday for Pigeon Pt to Pt
Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Canepa
MARINE...Canepa
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Prepared by Boulder-Creek.com Weather at: Sun Aug 30 04:30:03 PDT 2026
From the National Weather Service
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