FXUS66 KMTR 110714
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1214 AM PDT Sat Jul 11 2026

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

.KEY MESSAGES...
Updated at 1210 AM PDT Sat Jul 11 2026

 - Warmer temperatures continue into next week with Moderate
   HeatRisk returning early next week

 - Coastal Flood Advisory for up to 1.7 feet of inundation above 
   ground level is possible in low-lying areas near shorelines and
   tidal waterways

 - Slightly increasing confidence in potential for thunderstorms
   and elevated fire weather concerns Sunday into early next week

&&

.SHORT TERM...
Issued at 1210 AM PDT Sat Jul 11 2026
(Today and tonight)

Stratus coverage across the interior will be less widespread tonight 
as the marine layer compresses to around 500 ft. Stratus is expected 
to redevelop along the coast and SF Bay shoreline but not expected 
to extend much beyond more coastal areas. Patchy fog and drizzle 
become more likely along the coast during the early morning hours as 
the marine layer compresses. If you are driving early Saturday 
morning, watch for sudden changes in visibility and be prepared to 
slow down if necessary.

Upper level ridging continues to dominate the southwestern United 
States through much of the long term forecast. The center of this 
ridge will gradually shift eastward away from southern California 
towards the desert southwest Saturday into Sunday. Temperatures are 
forecast to warm slightly (2-3 degrees) on Saturday as the ridge 
strengthens and a compressed marine layer stays tied to the coast. 
Interior areas will feel this warm up more substantially than the 
coast with seasonally warm temperatures in the upper 80s to 90s 
expected. The SF Bay shoreline and coastal areas will stay 
seasonally cool. High temperatures along the bay will be in the 70s 
to 80s while coastal highs will be in the 60s to 70s. Minor HeatRisk 
is expected today with patchy Moderate HeatRisk across the warmest 
interior locations and higher terrain. The marine layer is expected 
to remain compressed around 500 ft again tonight. However, mid and 
high level clouds are expected to stream into the region Saturday 
night ahead of the monsoonal moisture surge arriving Sunday.

&&

.LONG TERM...
Issued at 1210 AM PDT Sat Jul 11 2026
(Sunday through Friday)

There are two main topics for the Long Term discussion: the 
potential for thunderstorms late this weekend into early next week 
and the return of Moderate HeatRisk early to mid week. 

On the synoptic scale, the center of the upper level ridge will 
gradually shift northeastward towards the northern Intermountain 
West late this weekend and remain in place through the remainder of 
the extended forecast. A monsoonal moisture surge is forecast to 
move into California from the Gulf of California late Saturday night 
into Sunday. This surge is bringing above normal moisture for this 
time of year with PWAT values between 1-1.3" expected which is 
around 150-200% of normal. Forecast soundings show the bulk of this 
moisture in the mid to upper levels of the atmosphere and much drier 
conditions at the surface. There is enough moisture available to 
support high based showers but the questions becomes will there be 
enough instability to result in thunderstorm development. Model 
guidance has trended upwards over the last few days in terms of 
forecast available MUCAPE/surface CAPE. By no means is this a 
substantial change, however, as models have gone from showing no 
instability to pockets of MUCAPE (less than 500 J/kg) across our 
CWA. Long range, deterministic guidance from the ECMWF and GFS have 
both started showing some potential for showers across our CWA with 
some potential for lightning. More interestingly, we are getting 
within range of high resolution models (HRRR, NAM, RRFS) which are 
consistently showing the potential for thunderstorms Sunday into 
Monday across our region. While instability still remains a limiting 
quantity, confidence is increasing slightly that we will see some 
sort of high based convection and potentially thunderstorm 
development late this weekend into early next week. Any storms that 
do develop are likely to be dry given their elevated nature but 
ensembles do indicate light rain may be possible with the strongest 
showers.

The monsoonal moisture surge will additionally bring widespread mid 
to high level clouds late this weekend into early next week. This 
will prevent overnight radiational cooling, trapping heat at the 
surface, and see overnight low temperatures rise. Monday and Tuesday 
mornings, interior low temperatures are forecast to be in the low 
60s while the higher elevations only drop into the upper 60s to 70s 
overnight. Daytime high temperatures will remain in the mid 80s to 
90s across the interior while the warmest interior areas reach the 
low 100s. Coastal areas stay cooler in the 70s to low 80s. Monday 
and Tuesday will see more widespread Moderate HeatRisk across the 
higher elevations and extending into urban areas. Make sure to 
listen to your body, take breaks in the shade, and stay hydrated if 
spending time outdoors early next week. Morning low temperatures 
trend cooler, back into the 50s, as mid and high level clouds 
coverage dissipates mid to late week. A slight cooling trend begins 
Friday with interior highs dropping back into the 80s as the center 
of the ridge shifts further east and troughing becomes more dominant 
over the Pacific.
&&

.AVIATION...
(06Z TAFS)
Issued at 935 PM PDT Fri Jul 10 2026

The marine layer stratus bank is regaining organization over the 
ocean, while inland locations within the marine layer see clouds
develop overhead. This combination of cloud formation and
advection makes the exact timing of arrival very tricky. The
forecast still leans on persistence, but the confidence is onset
timing is pretty low. I feel better about the clearing times in
the morning, however.

Vicinity of SFO...VFR as of this writing, but the walls are
closing in. OAK is reporting ceilings of 1,000 feet, with HAF at
700. When SFO does get their ceiling, the height should be in 
that ballpark.

SFO Bridge Approach...Will fill in later than SFO and clear
earlier.

Monterey Bay Terminals...I have no idea what will happen in the
next few hours. The Monterey Bay is clear, but there is a small
patch of clouds over the Monterey Peninsula that is occasionally
drifting over Jack's Peak to the terminal and retreating back.
Eventually IFR conditions will settle in for the night, but I just
can't say when with any confidence tonight.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 935 PM PDT Fri Jul 10 2026

A fresh NW breeze will diminish to moderate this weekend, as seas
gradually diminish. These more favorable conditions will continue
into early next week before strong winds return late week.

&&

.FIRE WEATHER...
Issued at 127 PM PDT Fri Jul 10 2026

Warm and dry conditions persist through much of next week, 
especially away from the coastal marine influences which are 
forecast to persist through much of next week. This will increase 
fire weather concerns as fuels rapidly dry out. Fire weather 
concerns further increase late this weekend into early next week 
as a surge of monsoonal moisture advects northward around the 
western periphery of the high pressure over the Desert Southwest 
and Intermountain West. If thunderstorms are able to develop, dry 
lightning and gusty, erratic outflow winds would be the main 
hazards. The limiting factor is the lack of instability over our 
region those days. Thus, we will continue to closely monitor these
conditions through the weekend. Given the combination of the 
potential for dry lightning and rapidly drying fuels, it is 
important to stay up to date on the forecast as it evolves.

&&

.BEACHES...
Issued at 450 AM PDT Thu Jul 10 2026

A Beach Hazards Statement remains in effect for Pacific coast 
beaches through this afternoon. Long period southwesterly swell 
will create an increased risk of sneaker waves and strong rip 
currents, as well as breaking waves up to 10 feet. This will be 
especially true for south and southwest facing beaches with 
moderate to steep slopes along the North Bay, San Francisco 
Peninsula, and Santa Cruz coasts. Sneaker waves can sweep across 
the shoreline without warning, pulling people into the sea from 
rocks, jetties and beaches. Dangerous swimming and surfing 
conditions and localized beach erosion can be expected. Stay off 
of jetties, piers, rocks, and other waterside infrastructure. 
Remain out of the water to avoid hazardous surf and NEVER turn 
your back on the ocean. Monitor local weather, surf and tide 
forecasts at www.weather.gov/mtr.

A Coastal Flood Advisory is in effect for minor high tide 
flooding through Thursday July 16th. The combination of a 
perigean spring tide (lunar perigee on 7/13 and new moon on 7/14) 
enhanced by 3-6 inches of additional water from thermal expansion 
and accumulated sea level rise since the tidal datum was 
established (1983-2001) will bring high tides up to 1.7 feet above
normal. This will lead to minor flooding of parking lots, parks 
and roads with isolated closures expected. For context, in June we
reached 2.0 feet above normal and in January we reached 2.5 feet
above normal.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 4 AM PDT Thursday for CAZ006-506-
     508.

     Coastal Flood Advisory from 8 PM this evening to 4 AM PDT 
     Wednesday for CAZ505-509-529-530.

PZ...Small Craft Advisory until 9 PM PDT Sunday for Pt Arena to Pt 
     Reyes 0-10 nm.

     Small Craft Advisory until 3 AM PDT early this morning for 
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras 
     Blancas 0-10 nm.

     Small Craft Advisory until 3 PM PDT Monday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Flynn
MARINE...Flynn

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Prepared by Boulder-Creek.com Weather at: Sat Jul 11 04:30:03 PDT 2026