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NWS Technical
Weather Discussion |
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FXUS66 KMTR 291715
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1015 AM PDT Wed Jul 29 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1244 AM PDT WED Jul 29 2026
- Breezy onshore winds expected each afternoon and evening through
midweek
- Gradual warming starting midweek, with Moderate HeatRisk for
interior locations through the weekend
- Elevated fire weather threat across the interior North and East
Bay, Diablo and Santa Lucia Ranges this week
- Hazardous beach conditions at the Pacific Coast with an
increased risk for sneaker waves and rip currents through the
weekend
&&
.UPDATE...
Issued at 940 AM PDT Wed Jul 29 2026
Water vapor imagery shows a deep trough of lower situated over the
West Coast, with a secondary system moving inland across the
Pacific Northwest. The imagery also shows very dry air aloft
parked over California. Closer to the surface though, the marine
layer deepened slightly overnight in response to the trough, and
pushed farther inland this morning than yesterday. In fact, low
clouds made it all the way inland to Napa and all the way down the
Salinas Valley. That said, the low clouds are starting to
retreat. While the low clouds clear from the inland areas, expect
them to linger once again along the coast today. Otherwise, expect
seasonal and pleasant day across the region, with temperatures
similar to those of yesterday. Forecast is handling these trends
well, so no update is planned at this time. Palmer
&&
.SHORT TERM...
Issued at 1243 AM PDT Wed Jul 29 2026
(Today and tonight)
Interesting water vapor imagery overnight with a few weather
features of note: impressive upper level ridge with monsoon
moisture sparking storms over the Desert SW into the Rockies, a
major hurricane Genevieve about 600 mi SW of Baja, and a weak dry
slot shortwave trough sweeping through CA. While dry at 400mb
over the Bay Area satellite fog product tells a different story.
While not continuous, a much more robust marine layer is present
tonight with stratus expanding over the coastal waters and
beginning to move inland.
Morning inland stratus will quickly fade and erode back to the
coast by mid-morning. Today will be a preview of what's to come
the next few days: fading marine layer by mid-morning with
warming inland temps. Wouldn't be surprised one bit if stratus
lingering along the coast for much of the day. Temperatures this
afternoon will be similar to Tuesday along the coast/bays with
highs 60s/70s (a few low 80s) and away from the coast/marine layer
influence temps will creep upwards with highs in the 80s to near
100.
One thing that will remain the same this afternoon will be the
winds. Given the temp difference from the coast to inland onshore
flow will bring breezy to gusty winds again. Winds will be
strongest this afternoon/early evening with gusts 30-40 mph.
For tonight: despite building 500mb heights and some areas of
offshore flow we will see the marine layer again with coastal
clouds moving inland. Thermal belts will remain active too.
&&
.LONG TERM...
Issued at 115 AM PDT Wed Jul 29 2026
(Thursday through Tuesday)
The big highlight for the long term will be the building inland
heat. Thankfully, onshore flow and lingering marine layer
influence will keep coastal areas in check temp wise. The large
upper level ridge currently sitting well to the east will build
westward Thursday into the weekend. Generally speaking the
forecast remains on track with warm to hot conditions across the
interior with the hottest days being Saturday and Sunday.
Confidence still remains high enough to keep some marine layer
influence limiting heat potential near the coast. One change to
tonight's forecast update are the temps for Saturday across the
interior, which have trended down. Still over 100 degrees, but
not shooting for 110 across interior Central Coast. This drop did
temper HeatRisk values a little bit. Regardless of that trend,
still expecting Moderate HeatRisk to develop across the interior
Thursday and persisting through at least Sunday. If you have
outdoor plans Thursday through Saturday across the interior be
prepared and follow some basic heat safety tips: Stay hydrated,
Never leave people or pets unattended in vehicles, and limit
activities during peak heating. The slight downward temp trend
could also be attributed to some beefy NW winds over the coastal
waters this weekend. ECMWF EFI highlights the strong winds over
the coastal waters, which could help to enhance upwelling.
Temperatures will ease a bit late Sunday through late Monday as
the large upper ridge flexes south with a passing trough to the
north. The upper level ridge rebuilds by Tuesday into Wednesday
causing temperatures to rise again. Longer guidance and the CPC
outlook shows another round of even hotter temps will be possible
around August 5 through August 8.
&&
.AVIATION...
(18Z TAFS)
Issued at 1015 AM PDT Wed Jul 29 2026
IFR-MVFR stratus is dissipating across the coastal and Salinas
Valleys, with patches of clouds hanging on at the immediate coastal
region. Moderate onshore pattern winds with some strong gusts to 25
kt will develop this afternoon and evening, with some IFR-MVFR
stratus returning to the SF and Monterey Bay regions, potentially
down into the Salinas Valley, through the late evening and overnight
periods. Stratus will dissipate through Thursday morning, near or
just after the end of the 24-hour TAF period.
Vicinity of SFO... Lingering MVFR ceilings should mix out within the
next two hours. Moderate west winds with strong gusts to 25 kt will
develop through the afternoon and evening hours with the skies
remaining generally clear through the late evening and early
overnight periods, with IFR-MVFR ceilings returning after midnight.
Stratus should dissipate through Thursday morning with moderate to
strong winds expected that afternoon.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... Stratus dissipation is imminent at SNS
while MRY may remain socked in through the day. Considered making
the MRY TAF sub-VFR through the TAF period, but moderate confidence
that there will be brief scattering in the afternoon. Moderate west
winds with gusts to 20 kt will develop in the afternoon, with
widespread IFR stratus returning as the winds diminish overnight.
Stratus clearing on Thursday morning is expected near or slightly
after the end of the TAF period.
&&
.MARINE...
(Today through Monday)
Issued at 1015 AM PDT Wed Jul 29 2026
Fresh to strong northwest breezes with near gale force gusts
persist through the remainder of the week into the weekend. Gale
force gusts with moderate seas are expected along coastal jet
regions along Big Sur and Point Reyes. Additionally, gale force
winds are possible for the northern outer waters by the end of the
weekend. Tropical activity produces long period swell across the
coastal waters into the weekend.
&&
.FIRE WEATHER...
Issued at 155 PM PDT Tue Jul 28 2026
The elevated fire weather threat will continue across portions of
the area through at least this weekend. Overnight RH recovery
will remain moderate to poor at locations at or above 2,000 feet
with values between 35 to 50 percent, with some favored locations
struggling to even reach 30 percent. This will be particularly
true across the Mayacamas, highest peaks of the East Bay Hills,
the Diablo Range, Santa Cruz Mountains, Santa Lucia and Gabilan
Ranges. Nocturnal drying (rapid decrease in RH through the pre-
dawn hours) may also transpire which will increase the burn period
or time in which fire behavior may remain active. Afternoon RH
will remain critically dry with values between 20 and 40 percent,
with far southern portions of the interior Central Coast
potentially seeing min RH near 10 percent. Energy Release
Components (ERC) are projected to climb above the 95th percentile
across the interior Central Coast. Individuals across the area are
advised to avoid activities that may spark a fire. Fire crews are
urged to exercise extra caution when executing any prescribed
burns, especially where fuels, topography, and weather align.
&&
.BEACHES...
Issued at 155 PM PDT Tue Jul 28 2026
Long period southerly to southwesterly swell of 16-18 seconds will
continue to impact our coastline over the next several days,
bringing hazardous beach conditions to the Central Coast and the
San Francisco Bay Area. Sneaker waves and strong rips currents
will be the primary conditions, with breaking waves up to 12 feet
along some south and southwest facing beaches and break points,
such as Santa Cruz, Pacifica, and parts of Stinson or Ocean Beach.
This can be particularly surprising when wave heights increase
suddenly after a period of seemingly tranquil wave action. In
fact, sneaker waves can have 20+ minutes in between the larger
sets (breaking waves) with significant "flat/calm looking" times
between them. Due to the long period, sneaker waves are powerful
and can catch beachgoers by surprise, resulting in people and pets
being swept into the cold, turbulent ocean. Rip currents are
strong enough to pull even the strongest swimmers away from shore.
Check marine conditions before you head out! Swim near a
lifeguard, if possible. Maintain a safe distance from the water,
and stay away from jetties, piers, beachside rocks, and other
waterside infrastructure. Never turn your back to the ocean and if
you have small children or pets at the beach, please keep an eye
on them. Hazardous beach conditions are anticipated to persist
through Saturday afternoon.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Saturday afternoon for CAZ006-
505-509-529-530.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
evening for Mry Bay.
Small Craft Advisory from 3 PM to 9 PM PDT Thursday for Mry Bay.
Small Craft Advisory until 3 PM PDT Friday for Pigeon Pt to Pt
Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt
Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 3 PM PDT Thursday for Pt Reyes to
Pigeon Pt 0-10 nm.
Gale Warning until 9 PM PDT this evening for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...DialH
MARINE...DialH
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Prepared by Boulder-Creek.com Weather at: Wed Jul 29 10:30:02 PDT 2026
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From the National Weather
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Revised:
29 Mar 2008 09:53 -0800 GMT
(Pacific) |
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