FXUS66 KMTR 111759
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1059 AM PDT Sat Jul 11 2026

...New AVIATION...

.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

&&

.UPDATE...
Issued at 910 AM PDT Sat Jul 11 2026

We are already seeing high clouds as monsoonal moisture advects 
northward around the western periphery of the high pressure over the 
southern California and Desert Southwest. This has resulted in the 
compression of the marine layer to around 500 feet, thus the lesser 
inland extend of stratus this morning. We expect these high clouds 
to persist throughout much of the day as mid/upper level moisture 
continues to advect across the region as the high pressure shifts 
northeastward. No major updates to the ongoing forecast. 

RGass

&&

.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 

&&

.AVIATION...
(18Z TAFS)
Issued at 1057 AM PDT Sat Jul 11 2026

VFR across the board with CIGs along the coast and mid-high level
clouds overheads. Trending much more favorable over the next 12
hrs due to high clouds and decreasing marine layer impacts. Winds
are relatively light to moderate this morning with stronger
onshore flow expected this afternoon/evening. CIGs return along 
the immediate coast early tonight, but inland impacts are less. 
Overall conf is moderate.

Vicinity of SFO...VFR with high clouds. NW winds with gusts up to
20 kt this afternoon. HREF/HRRR/NBM have trended to less chc
(<30 pct) for CIGs tonight so kept SFO VFR.

SFO Bridge Approach...Similar  to SFO.

Monterey Bay Terminals...Low CIGs will lurk in MRY Bay this
afternoon and then come into MRY first and then SNS early this
evening. Expect an earlier clearing time Sunday AM.   

&&

.MARINE...
(Today through Thursday)
Issued at 910 AM PDT Sat Jul 11 2026

Northerly flow will persist through the weekend. Winds will ease
south of Pigeon Point, but still remain moderate to fresh north of
the Golden Gate. A moderate northerly swell will remain as well.
Winds and seas build by the middle of next week.

&&

.FIRE WEATHER...
Issued at 453 AM PDT Sat Jul 11 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 later 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 453 AM PDT Sat Jul 11 2026

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 PM PDT Tuesday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...MM
MARINE...MM

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Prepared by Boulder-Creek.com Weather at: Sat Jul 11 12:30:02 PDT 2026