Las Lomas, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

319
FXUS66 KMTR 171813
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1113 AM PDT Sun May 17 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 140 AM PDT Sat May 16 2026

 - Breezy to windy conditions, especially across the North, East,
   and South Bay Mountains along with the Santa Cruz Mountains
   through Monday

 - Hazardous beach conditions through Monday

 - Hazardous marine conditions expected through the weekend

 - Elevated fire weather concerns continue through Monday across
   the interior with low humidities and strong gusts

&&

.UPDATE...
Issued at 955 AM PDT Sun May 17 2026

Winds are expected to increase again this afternoon/evening. A
Wind Advisory will go into effect at 11 PM PDT tonight and
continue through 11 AM PDT Monday for the higher elevations of the
North Bay, East Bay, South Bay, and Santa Cruz Mountains. Gusts up
to 50 mph are expected across the higher elevations with localized
gusts up to 60 mph possible along the highest ridgelines.
Otherwise the forecast remains on track.

&&

.SHORT TERM...
Issued at 140 AM PDT Sun May 17 2026 (Today and tonight)

Water vapor imagery shows a broad trough of low pressure over the
West this morning, with one disturbance currently moving across
Nevada. In response to this system beginning to shift east,
pressure gradients are starting to relax from their earlier peak.
At this time, the SFO-ACV is down to -9.5 mbs, while the SFO- LAS
is down to 12.6 mbs. Even though it is still breezy out there,
gusts are mostly less than 40 mph along the coast. Therefore, have
canceled the Wind Advisory to better reflect the current
conditions.

That being said, the winds will still be a concern over the next
24 to 36 hours though, as another disturbance currently over
Western Washington and Oregon dives into the Great Basin later
today and tonight. This disturbances has a more traditional inside
slider trajectory. As a result, expect another round of dry and
gusty winds to develop. This time though, it will be the offshore
pressure gradients that increase. North to northeast 925 mb and
the 850 mb winds will increase to 40 kts over the North and East
Bay after 06z Mon, before spreading south and west through the
night. Therefore, have issued a new Wind Advisory focusing on the
North, East, and South Bay Mountains as well as the Santa Cruz
Mountains for Sunday night through late Monday morning. At this
point in time, expect the gusts to be in the 45 to 55 mph range,
with local gusts above 60 mph at the favored locations like Mount
Diablo. Very dry conditions will accompany these winds, and should
a fire start in dry grass areas, the fuels will carry that fire.
Therefore, caution is encouraged if you have plans to be working
outdoors. One less spark.

&&

.LONG TERM...
Issued at 140 AM PDT Sun May 17 2026 (Monday through Saturday)

As this the broad trough starts to push east on Monday, high
pressure will start to rebuild over California, and be the dominate
weather feature through midweek. As a result, a gradual warming
trend will develop, especially across the inland areas. Expect
some warming at the coast as well, but it will be more moderated,
especially once the marine layer re-estabilishes itself by
Wednesday. Models start to diverge towards the end of the week and
next weekend, with some clusters suggesting another trough forming
off the West Coast, while others suggest a flatter ridge, while
others suggest the ridge persisting. Therefore, confidences is
relatively low on what will actually happen. However, believe the
marine layer will likely continue to bring low clouds and fog to
the coastal areas. The question is just how far inland that
influence will go.  Palmer

&&

.AVIATION...
(18Z TAFS)
Issued at 1113 AM PDT Sun May 17 2026

Strong surface high pressure over the eastern Pacific and far
northern CA is resulting in a moderate to strong northerly 7.4 mb
ACV-SFO pressure gradient including 2.0 mb SFO-SAC onshore pressure
gradient. RDD-SAC is 4.1 mb while the surface pressure will also
build over the Great Basin increasing the WMC-SFO gradient tonight
and Monday morning as well. Mixing and drying within the boundary
layer will result in continuing VFR. Windswept seas leading to
sea spray and sea salt aerosols will continue to result in areas
of reduced visibility in haze /MVFR/ near the coastline. Surface
winds at the terminals ease tonight while lower level winds will
increase resulting in areas of low level wind shear tonight and
Monday morning. Lower level winds decrease while diurnal vertical
mixing returns Monday reducing low level wind shear during the day
Monday.

Vicinity of SFO...VFR. West wind increasing to 20 to 30 knots in
the afternoon to mid evening. Wind decreasing tonight to 10 knots
with low level wind shear tonight and Monday morning. Northwest
wind strengthens by late Monday morning with a decrease in low
level wind shear.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR except for areas of haze /MVFR/. West
winds 15 to 25 knots, easing to 5 to 10 knots tonight and Monday
morning. Low level wind shear tonight and Monday morning.

&&

.MARINE...
(Today through Friday)
Issued at 955 AM PDT Sun May 17 2026

Strong surface high pressure will remain nearly stationary over
the eastern Pacific this week. This will result in widespread
strong and gusty northwest winds across the coastal waters. Rough
seas continue through late today with up to 19 ft waves during the
strongest winds, but seas will ease into the work week.

&&

.FIRE WEATHER...
Issued at 443 AM PDT Sun May 17 2026

Strong and gusty north to northwest winds continue to affect the
region, shifting slightly into Sunday afternoon, and becoming
north to northeast. Expect peak gusts greater than 30 mph for most
areas, with around 45 to 55 mph along through gaps and passes,
and across higher terrain. Daytime humidity retentions loos to
stay around 10- 25% across the interior regions and higher peaks,
with limited overnight humidity recoveries. Strong winds persist
into the early Monday before diminishing. Humidities will be slow
to recover into the work week as a light offshore flow will
continue to affect the district.

&&

.BEACHES...
Issued at 140 AM PDT Sat May 16 2026

A Beach Hazards Statement remains in effect for west facing
beaches along the Pacific Coast through 9 AM Monday due to strong
winds over the marine environment leading to hazardously strong
wind waves and overall rough seas. Dangerous swimming, boating,
and surfing conditions can be expected. Large breaking waves can
overpower swimmers resulting in significant physical injury and
increase the risk of drowning. Gusts will stay strong along the
immediate coast, causing blowing and drifting sand and increased
sea spray. Water rescue attempts may be hampered by reduced
visibilities from the sea spray. Remember, NEVER turn your back on
the ocean.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Monday morning for CAZ006-505-
     509-530.

     Wind Advisory from 11 PM this evening to 11 AM PDT Monday for
     CAZ504-512-514-515.

     Coastal Flood Advisory until 3 AM PDT Tuesday for CAZ506.

PZ...Gale Warning until 3 AM PDT Monday 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 Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to
     Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

     Gale Warning until 9 PM PDT this evening for Mry Bay.

     Storm Warning until 3 PM PDT this afternoon for Pt Arena to Pt
     Reyes 10-60 NM.

     Gale Warning from 3 PM this afternoon to 9 AM PDT Monday for Pt
     Arena to Pt Reyes 10-60 NM.

&&

$$

SHORT TERM...Palmer
LONG TERM....Palmer
AVIATION...Canepa
MARINE...Canepa

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