FXUS66 KMTR 171203
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
503 AM PDT Wed Jun 17 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1245 AM PDT Wed Jun 17 2026
- Minor coastal flooding due to higher than normal high tides
anticipated across low-lying coastal areas.
- Hazardous beach conditions through early Thursday morning with
increased risk of sneaker waves and strong rip currents.
- Minor HeatRisk through the end of the week with temperatures
cooling to below normal.
&&
.SHORT TERM...
Issued at 1245 AM PDT Wed Jun 17 2026
(Today and tonight)
A marine layer 1000-1500 feet deep will bring extensive cloud
cover to the coast and adjacent valleys this morning. Patchy
drizzle has been observed along the coast and will continue
through the morning, especially over the higher terrain. By the
afternoon, clouds should retreat back to the coastline with mostly
sunny skies. The marine influence combined with breezy onshore
winds this afternoon will keep areas near the coast relatively
cool, with highs mainly in the 60s to lower 70s. Overall,
conditions will be very similar to Tuesday. Marine stratus will
return tonight, along with patchy drizzle redeveloping along the
coast.
High pressure over the area will start to weaken today, which
will bring about 2-5 degrees of cooling inland. This will place
temperatures near normal for mid June with highs in the upper 70s
to lower 90s. Most areas will see Minor HeatRisk today with only
isolated pockets in the interior of Moderate HeatRisk. Despite the
slight cooling, continue to practice smart heat safety
(especially for those more sensitive to the heat) by limiting time
outdoors, taking frequent breaks in the shade (if outdoors), and
staying hydrated.
Tidal flooding continues across low-lying coastal and Bayshore areas
through Thursday morning as high astronomical tides combine with
surge effects from wind, swell, and thermal expansion to bring us
the highest tides of the summer season. High tides are expected to
be 1.7 ft above normal (7.5 ft MLLW) at 12:56 AM early this
morning, and 1.2 ft above normal (7.1 ft MLLW) at 1:51 AM on
Thursday. In addition, the long-period southerly swell continues,
which increases the risk for sneaker waves and strong rip
currents, with a Beach Hazards Statement out through Thursday
morning. See the BEACHES section for more information, but the
main takeaway is to never turn your back to the ocean!
&&
.LONG TERM...
Issued at 1245 AM PDT Wed Jun 17 2026
(Thursday through Tuesday)
A trough off the coast will approach the area on Thursday and
further weaken the ridge. This will continue the cooling trend
across inland areas, with highs dropping by around 5 degrees. The
trough will begin to move onshore on Friday. Shower and
thunderstorm potential associated with the trough will stay
primarily over the higher terrain to the north and east of the
area as a deep marine layer greatly inhibits any thunderstorm
potential. However, there will be enough elevated instability for
a 5% chance of thunderstorms across far northern Napa and Sonoma
counties Thursday night and Friday with lower chances to the
south.
The trough will help to deepen the marine layer Friday into the
weekend with breezy onshore afternoon/evening winds. The inland
cooling trend will continue with highs Friday and Saturday only
reaching the 70s to low 80s at the warmest locations, or about 5
to 15 degrees below normal. Coastal areas will remain relatively
cool due to the marine influence. Drizzle may also develop over
the coastal waters and along the coast. Troughing will weaken by
Sunday with ensembles in agreement that a ridge will rebuild
across the West early next week. This will bring a warming trend,
especially inland.
&&
.AVIATION...
(12Z TAFS)
Issued at 429 AM PDT Wed Jun 17 2026
Satellite shows low clouds have filtered in sufficiently this
morning, with CIGs currently at all TAF sites, mostly low- end
MVFR. Stratus has made it into LVK and SJC, likely to prevail
there through 15-16z this morning. Intermittent -DZ possible at
times this morning and again Thursday morning. The low clouds
retreat back to the coast beginning around 16z, and VFR should
prevail for all but the immediate coastal sites after 18z and into
the afternoon as gusty seabreeze winds return. Gusts around 15kts
through the afternoon, with highest confidence at SFO and APC.
The marine layer will filter in again tonight with slightly lesser
chances to reach LVK and SJC, which are expected to remain VFR
for Thursday morning (moderate confidence).
Vicinity of SFO...BKN-OVC stratus with bases around 1200ft MSL
will prevail through 16z before slowly retreating back towards
the coastline, potentially lingering nearby through 20-21z. Gusty
westerly winds increase around 20z, with intermittent gusts up to
18kts through 07z Thur before weaker Thursday morning. Similar
gusts for Thursday afternoon. Stratus fills in again after 07z
Thurs, although MVFR CIGs may occur as late as 09z. Clearing
likely by 15-16z Thur.
SFO Bridge Approach...Stratus will clear this morning at a similar
time as the terminal, 16-17z with VFR prevailing thereafter.
Lesser chances for clouds Thursday morning with likely SCT MVFR
for the bridge approach. 25-40% chance of BKN/OVC closer to
sunrise on Thursday.
Vicinity of SJC and OAK...Stratus with bases around 1000-1400ft
MSL will clear by 15-16z from SJC, around 2 hours before OAK,
with VFR for the afternoon. Gustier northwest winds develop after
20z, as high as 15kts. MVFR stratus will push into the area after
05z, although likely hold out from OAK until after 08z. Model
guidance puts chances for a CIG at SJC Thursday morning at around
10-15%, but confidence is low to moderate for this given that
stratus overperformed this morning.
Monterey Bay Terminals...BKN-OVC bases 1000-1300ft MSL continue
until around 17z, but stratus will remain in the vicinity into the
afternoon, especially for SNS. Low clouds with similar bases moves
into the terminals again this evening, potentially as early as
00z Thur for SNS, likely closer to 02z for MRY, prevailing through
all of Thursday morning.
&&
.MARINE...
(Today through Monday)
Issued at 429 AM PDT Wed Jun 17 2026
Fresh to strong winds will continue through mid-morning and then
begin to ease, with onshore pushes maintaining moderate to fresh
southwest winds for San Francisco and San Pablo Bays through the
afternoon and evening hours. The same onshore push will impact the
near coastal areas of Point Sur north to Point Pinos, and Pigeon
Point to the Golden Gate. Expect light to gentle winds for the
reminder of the week into the weekend with light to moderate seas
and weak southwesterly swell across the coastal waters.
&&
.BEACHES...
Issued at 1245 AM PDT Wed Jun 17 2026
Long period southerly swell at around 15 to 17 seconds will persist
through early Thursday as energetic storms in the Southern
Hemisphere continue to affect the California coast, especially for
south and southwest facing beaches. Hazardous beach conditions
are advertised, specifically for moderate to steeply sloped
beaches along the Pacific Coast of the North Bay, San Mateo, Santa
Cruz counties. A Beach Hazards Statement for Pacific Coast
beaches continues through 5 AM Thursday morning. Be sure to check
beach conditions before you head out. Sneaker waves will run up
the beach much farther than other waves, potentially catching
beachgoers by surprise and resulting in people being swept into
the water. Rip currents are strong enough to pull the strongest
swimmers away from shore. Swim near a lifeguard if possible. Stay
back from the beach, and away from jetties, piers, beachside
rocks, and other infrastructure near the water. Never turn your
back to the ocean!
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through late tonight for CAZ006-505-509-
529-530.
Coastal Flood Advisory until 5 AM PDT Thursday for CAZ006-506-
508.
Coastal Flood Advisory until 5 AM PDT early this morning for
CAZ505-509-529-530.
PZ...Small Craft Advisory until 9 AM PDT this morning for Pt Arena to
Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Tangen
LONG TERM....Tangen
AVIATION...Zuber
MARINE...JM
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Prepared by Boulder-Creek.com Weather at: Wed Jun 17 06:30:03 PDT 2026
From the National Weather Service
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