702
FXUS66 KMTR 041522
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
822 AM PDT Fri Jul 4 2025

...New UPDATE, MARINE...

.KEY MESSAGES...
Updated at 208 AM PDT Fri Jul 4 2025

 - Elevated fire weather concerns persist through Friday for the
   East Bay and Santa Cruz Mountains.

 - Northwest winds of 30 to 55 mph through Friday across gaps,
   passes, and some valleys.

 - Near normal temperatures with slightly below normal through the
   weekend with a gradual warming trend next week.

&&

.UPDATE...
Issued at 818 AM PDT Fri Jul 4 2025

Satellite imagery shows stratus mixing out across the East Bay and
the Salinas valley, lingering at the immediate coast with an Otter
Eddy noticeable within the Monterey Bay. Forecast remains on
track with no changes at this time. To re-emphasize the night
shift`s message: be careful with outdoor activities today; one
less spark means one less fire!

DialH

&&

.SHORT TERM...
Issued at 208 AM PDT Fri Jul 4 2025
(Today and tonight)

For the midshift and satellite features of note: still seeing
noticeable hot spots (10.3-3.9um band )associated with the Madre
fire to the south in SLO, a few lightning hold over fires up near
the OR/CA border, much less stratus covering the coastal waters,
some patchy stratus filling in along the coast, and stratus
covering Monterey Bay Region and Salinas Valley. Speaking of
stratus, the marine layer remains, but has compressed thanks to
rising 500mb heights as the shortwave trough from Thursday tracks
eastward. Other items of note on the mid are the winds. While
onshore flow pressure gradient has eased it still hovering near
4mb leading to gusts 40-50 mph across the East Bay passes.

For the Fourth of July holiday: as the night progresses expect
stratus to fill in more along the coast and locally inland. As
such, a cloudy start to the day for some areas. By the afternoon,
a few high clouds with pockets of low clouds along the immediate
coast. Temperatures will be pleasant for early July: 60s to mid
70s coast and 70s to low 90s inland or seasonably cool. Onshore
gradient will be slightly less today, but still greater than 4mb.
Therefore, breezy to gusty onshore will be possible once again.
Windiest locations will be inland gaps/pass with gusts
approaching or barely exceeding 50 mph. For evening activities:
pockets of coastal low clouds will begin to expand along the
coast. Coverage of low clouds overnight Friday will be similar to
Thursday.

It goes without saying, but be mindful with outdoor activities
today. Be one less spark. As noted below we still have one more
day of elevated fire weather concerns.

&&

.LONG TERM...
Issued at 255 AM PDT Fri Jul 4 2025
(Saturday through Thursday)

The longwave pattern over the weekend continues to advertise broad
upper level troughing initially before developing into another
cut-off low for Sunday/Monday. So what does this mean for
sensible weather? The patchy marine layer will become more
widespread and deeper. Additionally, breezy onshore flow will
remain, but not as strong as Thursday/Friday. Temperatures will
remain seasonably cool through Monday.

Late Monday into Tuesday the meandering upper low begins to lift
northward. Of greater importance will be the very robust area of
high pressure over the Four Corners building westward into CA.
The initial building of the high will be buffeted by the upper
low. The upper low finally lifts northeast and rides over the
ridge by Thursday. This will allow our region to feel the more
full influence of the robust high pressure. In the big picture, a
gradual warming trend will kick off Tuesday and peak across the
interior Central Coast on Thursday. Probabilities of exceeding
100 degrees will be highest for interior Monterey/San Benito at
70-80%. The coast will be spared again as onshore flow remains.
This upcoming round of heat will be similar to previous heat
events this year - large temperature spread from the coast to
interior. The hottest interior locations will also reach the
moderate HeatRisk category. As always with upper lows and an
evolution upper level pattern there is some uncertainty. This
longer range heat potential will be fine tuned over the coming
days.

&&

.AVIATION...
(12Z TAFS)
Issued at 459 AM PDT Fri Jul 4 2025

Stratus has developed along the coastline and is filtering into the
SF Bay region. Confidence is low to moderate that stratus will reach
SFO and OAK at least temporarily this morning with slightly higher
confidence in stratus reaching OAK than SFO. Stratus is expected to
clear by mid to late morning before returning to coastal airports
late this evening/overnight. Winds generally remain onshore through
the TAF period with breezy conditions during the afternoon and
evening hours.

Vicinity of SFO...Stratus is starting to filter into the SF Bay with
NAM and LAMP guidance suggesting stratus will continue to build into
the bay. Confidence is low to moderate that stratus will at least
temporarily reach SFO this morning with highest likelihood between
12Z to 16Z this morning. CIGs look to build in early tomorrow
morning with CIGs most likely to develop around 12Z but some
guidance does suggest it developing as early as 09Z. Gusts to around
30 knots are expected during the afternoon and evening as moderate
westerly winds develop.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Moderate confidence in MVFR CIGs continuing
at MRY and SNS through mid to late this morning. Satellite shows an
otter eddy developing over the Monterey Bay which may temporarily
bring VFR conditions to MRY and SNS. Moderate westerly winds are
expected this afternoon and evening before winds ease overnight.
Confidence is moderate that stratus will return to MRY early
tomorrow morning with models generally in agreement. Confidence is
slightly lower for SNS with models hinting at a later return of
stratus closer to 12Z tomorrow morning.

&&

.MARINE...
(Today through Wednesday)
Issued at 818 AM PDT Fri Jul 4 2025

Fresh to strong northwest breezes and moderate seas continue
through the weekend before winds ease early next week. Low-
amplitude long period south swell will continue through the end
of next week. Winds look to increase and significant wave heights
look to build beginning late next week.

&&

.FIRE WEATHER...
Issued at 3 AM PDT Thu Jul 4 2025

Breezy onshore flow persist overnight with gusts 30-50 mph.
Thankfully, most areas are seeing some marine influence with
at least moderate humidity recovery. Winds may ease slightly
before sunrise. Onshore flow will ramp back up this afternoon as
the Central Valleys heats up. RH values will drop, but be tempered
by onshore flow keeping them from really bottoming out. That being
said, strong winds for inland gaps/passes and moderate RH will
lead to elevated or near critical fire weather concerns. Grasses
and finer fuels remain cured and available, and given the
potential for new ignitions due to the holiday weekend, an
increase in initial attack type activity should be expected by
local fire personnel. Less favorable burn conditions are
anticipated this weekend as the marine layer deepens and invades
parts of the area. However, far interior portions of the Bay Area
and Central Coast, as well as regions above 1500-2000 feet may
still remain within an airmass characterized by near-critical
humidity and winds where there may remain some potential for fire
spread/growth.

MM/Bain

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Saturday for SF Bay N of Bay
     Bridge.

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

     Small Craft Advisory until 3 PM PDT Saturday 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.

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

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

     Gale Warning until 3 AM PDT Saturday for Pt Pinos to Pt Piedras
     Blancas 0-10 nm.

&&

$$

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

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