FXUS66 KMTR 071836 AAA
AFDMTR
Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
1136 AM PDT Tue Jul 7 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 1238 PM PDT Mon Jul 6 2026
- Seasonably cool temperatures through today before a warming
trend arrives for the second half of the week
- Marine layer stratus develops each evening and overnight
before retreating to the coast each morning and afternoon
- Long period southwest swell causes an increased risk of
sneaker waves and strong rip currents today through Friday
&&
.UPDATE...
Issued at 916 AM PDT Tue Jul 7 2026
No major changes to the short term forecast. Overcast conditions are
likely to continue through late this morning as stratus clears
slowly across the region. The marine layer will remain relatively
deep (~1500-2000 ft) again tonight with widespread stratus expected
again tonight. Warmer temperatures remain on track for the interior
Central Coast and far interior North and East Bays starting
Wednesday. More notably, there is increasing potential for
thunderstorms to develop across portions of our warning area Sunday
into Monday. Fire weather concerns will be elevated if thunderstorms
are able to develop so make sure to keep an eye on the forecast as
we get closer in time to this event.
&&
.SHORT TERM...
Issued at 157 AM PDT Tue Jul 7 2026
(Today and tonight)
Satellite and surface observations show a well established and
widespread marine layer stratus pattern. Onshore winds prevail
due to a 3.1 mb SFO-SAC onshore pressure gradient. Sea surface
temperatures in the coastal waters vary from the 50s to lower 60s
(approx 1F to 4F above July normals). A clear night above the
stratus will allow for radiative cooling to space furthering
stratus development to daybreak. A radiative and gentle upsloping
cooling feedback loop may produce patchy light drizzle during the
overnight to predawn hours. A stable weather pattern continues
with 500 mb heights slightly above normal (near 587 decameters) at
~ 75th percentile for early July. Stratus will mix out inland
with patchy stratus lingering along the immediate coastline today
under diurnal surface warming. Daytime highs are forecast to
reach the 60s at the coast and around the SF Bay Shoreline to the
70s/80s inland to the 90s far inland. Stratus redevelops and moves
back inland tonight. Lows tonight are forecast to reach the 50s most
places to the lower to mid 60s at higher elevations near the marine
layer temperature inversion.
&&
.LONG TERM...
Issued at 157 AM PDT Tue Jul 7 2026
(Wednesday through Monday)
CA is currently on the western side of a high pressure system
centered over CO/NM/AZ and northern Mexico. Over the next 24-48
hours the high center will retrograde to just west of southern CA
where it'll become stationary during mid-week then is forecast to
advance northeastward late in the week and weekend. Daytime highs
will warm through mid-late week including a few areas getting
above 100F in the southern interior Thursday and Friday.
With approx 6 longwave troughs in the northern hemisphere, a
strong meridional temperature gradient and an ongoing negative
Pacific Decadal Oscillation this combination will place a longwave
trough over the eastern Pacific and as mentioned nudge the high
northeastward. The temporary westward motion of the aforementioned
high then its northeastward motion away from CA may transport
increasing 700-500 mb layer humidity and instability on southerly
winds close to and possibly over our forecast area over the
weekend and early next week. Recent global model guidance has
hinted at showery qpf and it's too soon to say if lightning will
be in the mix. We can have a marine layer while separate from this
high up in the atmosphere an elevated layer of humidity and
instability can move over the top of the marine air. Trying to
detect if there is a recent EPS/GEFS ensemble model trend in the
500 mb synoptic pattern: It does look like the 500 mb high is
shifting slightly northeast in recent trends, a sign of strength
in the westerlies and this may help mitigate the warm up prior to
any instability arriving. It's difficult to say with any certainty,
the door to higher humidity coupled to instability may still reach
here. Stay tuned to further updates.
&&
.AVIATION...
(18Z TAFS)
Issued at 1130 AM PDT Tue Jul 7 2026
A persistent stratus deck, characterized by IFR to MVFR ceilings
will continue to gradually erode from east to west this
afternoon. However, the clearing trend has been slow and
confidence is a little lower than normal with regard to specific
times, particularly at coastal sites. While VFR is advertised
between 20Z-23Z this afternoon at all TAFs, it's quite probable
that it's short-lived. Persistent onshore flow is forecast to
translate into an early evening (01Z-05Z) return of MVFR and IFR
ceilings. The potential for LIFR ceilings and IFR visibility is
greatest at HAF, STS, and APC, though low confidence precludes
mention in the TAFs at this time. Higher confidence does exist in
VFR by 21Z Wednesday, but for most locales, this is after the
current valid TAF cycle.
Vicinity of SFO...MVFR is forecast to prevail through 21Z, though
confidence is low to medium. Winds are anticipated to funnel
through the gap with peak gusts just under 30 knots this
afternoon. While there remains uncertainty in VFR this afternoon,
confidence is high that MVFR will be in place by 03Z. Despite the
forecast of lower near surface moisture (relative to Tue AM), IFR
is forecast during the pre-dawn hours on Wed as onshore flow
persists. There's a greater chance for VFR Wed afternoon with
medium to high confidence.
SFO Bridge Approach...VFR will return 1 to potentially 2 hours
ahead of the main terminal this afternoon. Otherwise, similar to
SFO.
Monterey Bay Terminals...MVFR currently, but the VFR potential is
greatest at SNS as the eastern edge of a stratus bank erodes.
Intermittent MVFR is forecast through mid-afternoon here. An eddy
has developed near OAR and provide favorable trajectories for a
persistent fetch of MVFR stratus into MRY thru the afternoon. If
this eddy dissipates, however, clearing may transpire and VFR
could return to MRY sooner than forecast. Trends will be
monitored. IFR is forecast to make a return this evening between
03-04Z. Occasional-DZ cannot be discounted (and thus IFR
visibility) at MRY. At this time, confidence is too low to
include. IFR ceilings are forecast to lift into MVFR toward the
end of the TAF period, though eddy development may alter the
timing.
&&
.MARINE...
(Today through Sunday)
Issued at 916 AM PDT Tue Jul 7 2026
Moderate to strong breezes are forecast across area waters,
including the bays over the next 24 hours. Northwesterly swell
between 6 and 8 feet will continue, with approximately 2 to 3
foot secondary long period southerly swell persisting through the
week. While winds diminish to largely gentle breezes across bays,
strong breezes and rough seas will persist through early Thursday
across the Pacific coast waters.
&&
.BEACHES...
Issued at 1238 PM PDT Mon Jul 6 2026
A Beach Hazards Statement remains in effect for Pacific coast
beaches from Tuesday morning through Friday afternoon. Long period
southwesterly swell will create an increased risk of sneaker
waves and strong rip currents, as well as breaking waves up to 10
feet. This will be especially true for south and southwest facing
beaches with moderate to steep slopes along the North Bay, San
Francisco Peninsula, and Santa Cruz coasts. Sneaker waves can
sweep across the shoreline without warning, pulling people into
the sea from rocks, jetties and beaches. Dangerous swimming and
surfing conditions and localized beach erosion can be expected.
Stay off of jetties, piers, rocks, and other waterside
infrastructure. Remain out of the water to avoid hazardous surf
and NEVER turn your back on the ocean. Monitor local weather, surf
and tide forecasts at www.weather.gov/mtr.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through Friday afternoon for CAZ006-505-
509-529-530.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT
Wednesday for SF Bay N of Bay Bridge.
Small Craft Advisory until 9 PM PDT Wednesday for Mry Bay.
Small Craft Advisory until 3 AM PDT Friday for 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 from 3 PM this afternoon to 3 AM PDT
Thursday for Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 3 AM PDT Thursday for Pigeon Pt to Pt
Pinos 0-10 nm.
Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Friday
for Pigeon Pt to Pt Pinos 10-60 NM.
&&
$$
SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...Bain
MARINE...Bain
Visit us at www.weather.gov/sanfrancisco
Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea
Prepared by Boulder-Creek.com Weather at: Tue Jul 7 12:30:03 PDT 2026
From the National Weather Service
|