FXUS66 KMTR 131217
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
417 AM PST Fri Nov 13 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1200 AM PST Fri Nov 13 2026

 - Rain and wind come through this morning and afternoon

 - Coastal flooding due to high tides continues through high tide
   today

 - Hazardous beach conditions prevail with dangerous conditions
   Saturday

 - Periods of rain continue through the next week

&&

.SHORT TERM...
Issued at 1200 AM PST Fri Nov 13 2026
(Today and tonight)

KMUX radar is showing echoes from pre-frontal showers across the 
coastal regions from Big Sur to Sonoma County with some rainfall 
already being reported along the coastal ranges and other favored 
areas. So far tonight, around 0.14" have been reported at the Big 
Sur RAWS and 0.05" at the Oak Ridge RAWS in the Sonoma County 
coastal ranges. The isolated pre-frontal showers should continue 
through the night.

The weather picture features a deep upper level low centered off the 
Pacific Northwest that will  progress eastwards and bring a frontal 
system into the region. This frontal system will be the initial 
round of a series of storms that will extend through the seven-day 
forecast -- more on that in the next section. For this round, high 
resolution model output shows the main frontal rain band starting to 
enter the North Bay around the time of the morning commute, 
extending into the central Bay Area later in the morning into the 
early afternoon, and passing through the Central Coast in the 
afternoon hours. Rainfall totals will top out around half an inch to 
an inch across much of the Bay Area save the far interior East Bay, 
Santa Cruz County, and the Santa Lucia range. Rain totals in the 
Santa Clara Valley and the Monterey-Salinas area lie around a third 
of an inch to an inch while the interior parts of the Central Coast 
should expect a tenth to a third of an inch. Strong winds are 
expected to build as the front approaches with sustained winds 
generally around 15-30 mph and gusts of 30-40 mph across the region. 
Locally higher gusts to 50 mph are possible at the immediate coast, 
especially near Monterey Bay and the Big Sur coast, and through 
favored gaps and passes including the San Bruno Gap, the Altamont 
Pass, the Carquinez Strait, Bayshore locations along San Pablo Bay, 
and the Salinas Valley. Another concern will be the risk of 
thunderstorms embedded within the main rain band and potentially in 
the post-frontal environment. The cold low will be centered to our 
north, but will still bring cool enough air aloft to bring the 
MUCAPE values up to 100-300 J/kg. That would be within the top 10% 
of soundings at Oakland for practically any time of year. There is 
also strong shear aloft enhanced by the region coming within the 
left exit region of a jet streak visible at the 500 mb level, where 
the decelerating winds and vertical circulation support an area of 
upper level divergence, which would support convective activity in 
the area. A slight (15%) chance of thunder has been added to the SF 
Bay Area for this morning and afternoon as a result. K-Index values 
from the European model top out around 30 degrees C, which would 
support isolated thunderstorms. 

Behind the main front, the rain becomes showery and winds will 
diminish and turn towards the west and northwest. Highs today will 
be remarkably cooler than yesterday's with the lower elevations 
seeing highs in the upper 50s to lower 60s while the higher 
elevations of eastern Santa Clara County and the Central Coast drop 
into the lower to middle 50s. 

Hazardous beach conditions are forecast for the Pacific coast 
through the evening with dangerous conditions expected to develop 
into Saturday. A Beach Hazards Statement is currently in effect for 
the Pacific coast for breaking waves 15 to 20 feet along with an 
increased risk of sneaker waves and rip currents, while High Surf 
Warnings will go into effect 6 PM tonight into early Sunday morning 
due to surf heights of 25 to 35 feet accompanied by a high risk of 
sneaker waves and rip currents. In addition, coastal flooding 
concerns due to high tides persist at the bayshore locations along
San Pablo, San Francisco, and southern Monterey Bays through the 
high tide cycle today, along with coastal flooding along the 
Pacific coast due to wave runup impacts on Saturday. See the 
BEACHES section for more details.

&&

.LONG TERM...
Issued at 1200 AM PST Fri Nov 13 2026
(Saturday through Thursday)

Saturday will feature a lull in the rain with some lingering post-
frontal showers in the morning, as highs reach the lower to middle 
60s across the lower elevations. Then, a second frontal system comes 
through Sunday into the early part of Monday. At this time, it looks 
like the rainfall totals will be similar to Friday's system with 
generally beneficial effects. Another lull in the rainfall comes 
later Monday into Tuesday, before a third system comes into the 
region later on Tuesday through Wednesday and Thursday. It's a 
little too early at this stage to be confident on how much rain this 
third system will bring.

As we go through the week, the main point to watch will be soil 
saturation across the region. The initial rounds of rain will be 
generally beneficial, reducing our fire weather threat and 
recharging the snowpack across the Sierra Nevada. Flooding concerns 
will be minimal with nuisance flooding possible across urban areas 
and small streams. Outside of these areas, rainwater is absorbed 
into the ground, which at this time, remains rather dry. As the rain 
continues to arrive, local soils saturate and are no longer able to 
hold as much additional rainfall, thus diverting excess water onto 
the surface and streams and rivers. Wet soils will also increase the 
chance for shallow landslides across the Bay Area, leading to 
further damage to homes and properties. Beyond the seven-day 
outlook, the pattern remains active with a lean towards rainfall 
totals above the seasonal average through late November. We will 
need to monitor what this will mean for soil saturation and the 
possibility for landslides through the next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 417 AM PST Fri Nov 13 2026

Conditions are VFR-MVFR with scattered showers over the forecast
area. Southerly winds will strengthen ahead of a cold front that
is currently approaching the northern outer coastal waters. The 
cold front with rain and gusty winds /ceilings and visibilities 
MVFR to possibly IFR/ will move eastward across the forecast area
today, reaching the East Bay in the early afternoon and the north
Central Coast in the mid to late afternoon. Winds will diminish 
behind the front with showers /VFR-MVFR/ lingering tonight and 
Saturday morning. 

Vicinity of SFO...VFR-MVFR with increasing rain and a southerly 
wind up to cold frontal passage 20z today. Southerly wind will be
near 35 knots, along with post cold frontal wind gusts still near
35 knots until 00z (4 pm PST today). Southwesterly wind diminishes
to 10 knots tonight and Saturday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR-MVFR with increasing rain and a 
southerly wind up to cold frontal passage mid to late afternoon. 
Southerly wind will be near 30 knots, with post cold frontal wind
gusts 20-30 knots. Southwesterly wind diminishes to 10 knots 
tonight and Saturday morning. 

&&

.MARINE...
(Today through Wednesday)
Issued at 346 AM PST Fri Nov 13 2026

Expect hazardous sea conditions today through early next week.
Strong southerly winds will develop ahead of a cold front moving
eastward across the coastal waters and bays today. Rain and a
slight chance of thunderstorms will accompany the cold front.
Winds will diminish tonight and Saturday with high pressure
temporarily building in across the coastal waters and bays.
Southerly winds will become gusty on Sunday ahead of the next cold
front. Significant wave heights will build up to 25 feet by
Saturday. Wave heights will decrease slightly by Sunday before
increasing on Monday.

&&

.BEACHES...
Issued at 1200 AM PST Fri Nov 13 2026

Beach Hazards Statement/High Surf Warning:

A Beach Hazards Statement is in effect through 6 PM tonight, at 
which point it gets replaced with a High Surf Warning through 4 AM
Sunday. A series of hurricane force low pressure systems will 
impact the NE Pacific through early next week. These storms will 
produce very high NW swell that will impact the coast with very 
hazardous conditions. Initially the forerunners will bring strong 
rip currents and sneaker waves through the day, while the 
breaking wave amplitude builds to 15- 20 feet. As the peak of the 
swell arrives on Saturday, breaking waves will reach up to 35 
feet. Occasional sets of 40-50 ft are likely at favored 
breakpoints. These waves bring tremendous power that will 
overpower anyone in the water and cause coastal erosion. The risk 
of drowning is very high this weekend. Do not go in the water, 
avoid climbing on the rocks or leaning over seawalls, and never 
turn your back on the ocean. Wave amplitude will abate somewhat on
Sunday before a new round of very high swell arrives Monday.

Coastal Flood Advisory (Today):

A combination of high astronomical tides and thermal expansion from 
warmer than normal water will result in tidal flooding concerns 
across Bayshore locations in the San Francisco, San Pablo, and 
Monterey Bays. At the San Francisco tide gauge, high tide is 
expected to be 1.5 ft above normal (7.3 ft MLLW) at 12:49 PM 
Friday 11/13. These predictions include up to 1.8 ft of surge that
will enhance the astronomical tide and flooding threat. High tide
varies up to 90 minutes earlier or later along the Pacific Coast 
and through the San Francisco Bay, respectively. In addition, 
long- period swell will create hazardous conditions along the 
Pacific coast beaches with an increased risk of sneaker waves and 
rip currents.

Coastal Flood Advisory (Saturday):

The swell on Saturday brings a different variety of coastal flooding 
as very large breaking waves pile up along the Pacific coast. 
Research shows wave run-up increases the mean water level by 10-20% 
of the breaking wave height across exposed beaches. This higher 
water elevation sets the stage for large waves to crash over sea 
walls and run up beaches onto adjacent infrastructure, particularly 
during high tide.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through this afternoon for CAZ006-505-
     509-529-530.

     Coastal Flood Advisory until 4 PM PST this afternoon for CAZ006-
     506-508-530.

     Coastal Flood Advisory from midnight tonight to 6 PM PST 
     Saturday for CAZ006-505-509-529-530.

     High Surf Warning from 6 PM this evening to 4 AM PST Sunday for 
     CAZ006-505-509-529-530.

PZ...Small Craft Advisory until 9 AM PST this morning for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 
     NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to 
     Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Gale Warning from 9 AM this morning to 3 PM PST this afternoon 
     for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt 
     Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt 
     Reyes to Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Gale Warning until 9 AM PST this morning for Pt Arena to Pt 
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa

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Prepared by Boulder-Creek.com Weather at: Fri Nov 13 06:30:03 PST 2026