Altadena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

294
FXUS66 KMTR 191132
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
432 AM PDT Sat Jul 19 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 209 PM PDT Fri Jul 18 2025

 - Seasonal temperatures through the end of the weekend. Below
   normal temperatures return Monday.

 - Localized elevated fire weather threat continues across the
   higher elevations with dry conditions expected this weekend.

 - Winds strengthen Sunday and Monday along the coast, the higher
   terrain, and mountain gaps/passes.

&&

.SHORT TERM...
Issued at 247 AM PDT Sat Jul 19 2025
(Today and tonight)

Another night shift and another round of marine layer stratus.
Despite similar sensible weather there are some minor
differences. The best way to describe the longwave pattern over
the forecast area is the "high pressure squeeze play". A few upper
level lows (SW British Columbia, well offshore of NorCal, and
SoCal/Baja border) all surround an area of high pressure overhead.
The "squeezed" high pressure didn`t completely erase the marine
layer, but definitely compressed it. Pt Sur and Bodega Bay
profilers are reporting a marine layer depth near 1200-1500 feet.
The compression of the marine layer is reflected with lower CIG
heights at area airports, spotter reports of fog, drizzle/bucket
tips, and webcams showing fog.

Despite a cloudy start to the weekend inland sunshine is expected
with coastal clouds by this afternoon. A similar sight that we`ve
been seeing the past few days. That being said, the high pressure
overhead will lead to slightly warmer temperatures today,
especially away from the coast. Highs will generally be in the
60s/mid 70s coast/bays and 70s to lower 90s inland...locally upper
90s interior Central Coast. Despite the warm up these forecasted
highs are still below normal for late July.

Saturday night into Sunday morning will feature another marine
layer push, but on the compressed.

Elevated fire weather concerns remain above the marine layer.
We`re pushing nearly a week of little to no relief for the high
elevation regarding humidity recovery. Current obs shows RH below
20% for some of the higher peaks.

&&

.LONG TERM...
Issued at 328 AM PDT Sat Jul 19 2025
(Sunday through Friday)

Longwave pattern shift to kick off the long term. The "high
pressure squeeze play" quickly comes to an end as the high gets
pushed southward. The upper level low over SW BC and its
associated trough deepens over the PacNW and NorCal, which helps
with the southward push of the high pressure. The deepening trough
will end any warm up and deepen the marine layer. Subtle cooling
will be seen on Sunday with more widespread cooling on Monday into
next week. The upper trough will also lead to increasing
northerly flow. The increase in wind has been advertised by the
models for several days now and the 00Z run is no different.
Strongest winds will be Sunday night lingering into Monday
afternoon/evening over the coastal waters, higher peaks, inland
gaps/passes. While not strong enough to warrant a wind advisory
there will be a 6-8 hr window with some solid wind, especially
the East Bay passes. Goes without saying, but the winds will
increase fire weather concerns too. Winds will finally ease late
Monday night.

Cool and relatively quiet weather continues toward the end of the
month.

&&

.AVIATION...
(12Z TAFS)
Issued at 432 AM PDT Sat Jul 19 2025

Stratus, patchy fog and drizzle /MVFR-LIFR/ this morning mixes out
to VFR-MVFR from late morning to afternoon. Best chances of VFR
will be far inland. Stratus, patchy fog and drizzle /MVFR-LIFR/
return tonight and Sunday morning.

Vicinity of SFO...Stratus /IFR/ mixes out to VFR by 1930z today.
Stratus /IFR/ returns 10z Sunday morning. West wind 10 to 15 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Stratus, patchy fog and possibly a few
patches of drizzle /IFR-LIFR/ until late morning, then MVFR-VFR
through the afternoon. Stratus, patchy fog /IFR-LIFR/ return
tonight and Sunday morning.

&&

.MARINE...
(Today through Thursday)
Issued at 423 AM PDT Sat Jul 19 2025

Northwest breezes will continue across much of the coastal waters
through Monday, winds easing next week. Gusty winds, potentially
hazardous to small craft, also develop each afternoon and evening
through the Golden Gate, into the Delta and the favored coastal
jets off Pigeon Point and the Big Sur coastline. Slight to
moderate seas persist through the remainder of the forecast
period.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM this morning to 9 PM PDT this
     evening for SF Bay N of Bay Bridge.

     Small Craft Advisory from 9 AM to 9 PM PDT Sunday for SF Bay N
     of Bay Bridge.

     Small Craft Advisory until 9 AM PDT this morning for Pt Pinos to
     Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT Sunday
     for Pt Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Canepa
MARINE...Canepa

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