Altadena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

992
FXUS66 KMTR 112327
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
427 PM PDT Wed Jun 11 2025

...New AVIATION...

.SYNOPSIS...
Issued at 301 PM PDT Wed Jun 11 2025

Stratus returns to portions of the Bay Area and Central Coast
overnight with coastal drizzle likely tomorrow. Breezy afternoon
onshore winds continue through the forecast period with highs
lingering in the 70s to 80s and into the 90s across the far
interior regions for much of the forecast period.

&&

.SHORT TERM...
(This evening through Thursday)
Issued at 301 PM PDT Wed Jun 11 2025

Stratus has mostly receded offshore except along the coastlines of
Marin and San Mateo Counties where some continues to linger. This
retreat will be fairly short lived with stratus returning to
portions of the Central Coast and Bay Area again this evening. The
marine layer looks to remain around 2000 ft again tonight which
would support stratus pushing into the Central Coast and San
Francisco Bay shoreline region. However, cloud cover is expected to
be slightly more limited tonight than it has been over the previous
days with high resolution guidance keeping the North Bay clear
tonight. One reason for this is that a weak passing shortwave trough
allowed the marine layer to deepen to around 2300 ft last night (as
seen on the 12Z OAK sounding this morning) which allowed stratus to
penetrate deep into the Bay Area. This shortwave trough has since
exited the region with more zonal flow returning as high pressure
builds over the Intermountain West. In terms of stratus clearing, it
has been trending slightly earlier in the morning each day this
week. This same trend looks to hold true tomorrow with stratus to
clear by mid to late morning across the region. This earlier
clearing of stratus will help to increase confidence that sites will
reach their forecasted high temperatures across the region. This is
unlike Monday and Tuesday where prolonged stratus coverage decreased
the amount of solar radiation able to reach the surface and kept
temperatures much cooler than originally forecast. High temperatures
on Thursday will be slightly warmer than those observed today with
highs in the upper 70s to upper 80s across the interior and in the
60s to low 70s closer to the coastline. Breezy afternoon winds
between 20 to 30 mph are expected across mountain gaps/passes and
across the higher terrain this afternoon/evening and again Thursday
afternoon/evening. Conditions are drying out across the interior
which in combination with breezy afternoon/evening winds may result
in an increased risk of grass fires - see Fires Section below -
through the weekend. &&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 301 PM PDT Wed Jun 11 2025

Things remain fairly quiet through the extended with zonal flow to
very weak ridging persisting Friday into the weekend. This will keep
the forecast across the interior fairly similar to what we have
already seen this week with highs in the 70s to low 80s and mid 60s
to low 70s along the coastline. The interior Central Coast will
remain warm through the weekend with highs in the 80s to low 90s.
The main question continues to be the progression of a weak upper
level trough (low pressure) through the Bay Area Sunday evening into
Monday. Model guidance has slowed down the troughs arrival slightly
and pushed into later into Monday with the trough exiting the region
late Monday into early Tuesday. Cluster guidance does indicate a
chance for the trough to persist through Tuesday but that scenario
seems unlikely. Temperatures will remain in the upper 70s to low 80s
across the interior on Monday before a warm up begins Tuesday with
temperatures reaching into the upper 80s to low 90s. Diurnally
breezy to gusty onshore winds continue across mountain gaps/passes,
elevated terrain, and portions of the coastline through the end of
the forecast period. Highest confidence is in gusts between 20 to 30
mph with funneling in gaps/passes potentially resulting in isolated
stronger gusts.

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 301 PM PDT Wed Jun 11 2025

Things remain fairly quiet through the extended with zonal flow to
very weak ridging persisting Friday into the weekend. This will keep
the forecast across the interior fairly similar to what we have
already seen this week with highs in the 70s to low 80s and mid 60s
to low 70s along the coastline. The interior Central Coast will
remain warm through the weekend with highs in the 80s to low 90s.
The main question continues to be the progression of a weak upper
level trough (low pressure) through the Bay Area Sunday evening into
Monday. Model guidance has slowed down the troughs arrival slightly
and pushed into later into Monday with the trough exiting the region
late Monday into early Tuesday. Cluster guidance does indicate a
chance for the trough to persist through Tuesday but that scenario
seems unlikely. Temperatures will remain in the upper 70s to low 80s
across the interior on Monday before a warm up begins Tuesday with
temperatures reaching into the upper 80s to low 90s. Diurnally
breezy to gusty onshore winds continue across mountain gaps/passes,
elevated terrain, and portions of the coastline through the end of
the forecast period. Highest confidence is in gusts between 20 to 30
mph with funneling in gaps/passes potentially resulting in isolated
stronger gusts.

&&

.AVIATION...
(00Z TAFS)
Issued at 426 PM PDT Wed Jun 11 2025

MVFR-IFR stratus persists along the coast from Point Reyes southward
to the San Mateo Peninsula, with scattered patches of stratus near
the Monterey Peninsula and clear conditions everywhere else. Gusty
onshore winds will continue through the evening hours, becoming
light away from the immediate coast overnight. Stratus is expected
to build inland south of the Golden Gate, with moderate confidence
in a transitory ceiling at SJC and LVK on Thursday morning. Stratus
will clear through Thursday morning and breezy winds will resume in
the afternoon. Some high resolution models are even predicting that
HAF may scatter out before the end of the 24-hour TAF period,
although this is a low confidence forecast for the time being.

Vicinity of SFO... MVFR ceilings have arrived at the terminal and
will continue through the night, dipping to IFR later in the
evening. Gusty west winds continue through the evening hours, with
wind gusts up to 30 knots. Wind gusts over 35 knots are not expected
for the rest of the day. Stratus will mix out Thursday morning.
Strong and gusty west winds resume Thursday afternoon with a low
probability (around 10-20%) for wind gusts over 35 knots.

SFO Bridge Approach... The approach path remains clear with lower
confidence for stratus impacts to the approach path overnight than
over the terminal. Otherwise similar to SFO.

Monterey Bay Terminals... VFR conditions along with breezy northwest
winds continue through the next couple of hours. Monitoring
scattered clouds over MRY for poential ceiling development earlier
than the current forecast. IFR-LIFR ceilings then continue through
the night before dissipating sometime Thursday morning. Moderate
confidence in timing of clearing at MRY. Breezy onshore winds resume
Thursday afternoon.

&&

.MARINE...
(Tonight through next Monday)
Issued at 301 PM PDT Wed Jun 11 2025

Northwesterly winds will continue over the coastal waters heading
into the weekend. Winds will increase Wednesday night leading to
locally hazardous conditions with occasional gale force gusts
developing near Point Reyes and south of Point Sur. Moderate to
rough seas will prevail through the week.

&&

.FIRE WEATHER...
Issued at 301 PM PDT Wed Jun 11 2025

While the marine layer will remain in some capacity over the next
few days, what happens above the marine layer is more of a fire
weather concern.  The last night or two have featured moderate to
poor recoveries above the marine layer and that will continue
Thursday night and Friday.  In fact, some locations are hitting
single digit and lower teens for RH values. Hi-res models even
indicate a burst of NE flow late tonight into early Thursday over
the N Bay. Not overly strong, but this will further enhance any
drying. There is some quote, recovery, during the daytime, but
another factor comes in. The breezy onshore flow. Winds will
remain breezy each afternoon/evening through the Delta, and any
inland gap or pass. The combination of dry fine fuels (grasses),
lower RH, breezy winds with gusts in the 20-40 mph will elevate
fire weather concerns.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for SF Bay N of Bay
     Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

     Small Craft Advisory until 9 AM PDT Friday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt
     Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for SF Bay N of Bay
     Bridge.

     Small Craft Advisory until 9 PM PDT this evening for Mry Bay.

     Small Craft Advisory until 9 AM PDT Friday for Pigeon Pt to Pt
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt
     Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

&&

$$

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

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