957
FXUS66 KMTR 050445
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
945 PM PDT Fri Jul 4 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 1209 PM PDT Fri Jul 4 2025
- Elevated fire weather threat continues through Friday evening
for the East Bay and Santa Cruz Mountains.
- Northwest winds of 30 to 50 mph Friday afternoon and evening
across gaps, passes, and some valleys.
- Temperatures remain below seasonal averages into early next
week, with a gradual warming trend towards the later part of
next week.
&&
.UPDATE...
Issued at 912 PM PDT Fri Jul 4 2025
Skies have remained mostly clear across the Bay Area and Central
Coast, which is fantastic news for those enjoying 4th of July
activities this evening. Satellite has shown stratus starting to
slowly blossom across Marin, Alameda, and San Mateo counties. This
should continue to be a gradual development, with better stratus
development after midnight and perhaps closer to the pre-dawn
hours for some interior locations.
&&
.SHORT TERM...
Issued at 1209 PM PDT Fri Jul 4 2025
(This evening through Saturday)
Satellite imagery reveals generally clear skies across the region
with the immediate coast south of Big Sur the last refuge of the
coastal stratus. Broad upper level troughing continues to dominate
the weather with temperatures near or below seasonal averages. Highs
will reach the middle 70s to the lower 80s in the inland valleys, to
the lower 90s in the southern reaches of Monterey and San Benito
County, the middle 60s to lower 70s near the Bays, and the upper 50s
to the middle 60s at the Pacific coast. Breezy and gusty afternoon
winds will develop across the region, with gusts reaching 30 to 50
mph through the gaps and passes, along the coast, and through the
Salinas Valley.
As the evening goes on, patchy low clouds could develop along the
coast and on the west side of the Berkeley-San Leandro Hills, but
most regions should remain clear through early Saturday morning. The
City, in particular, could very well remain clear throughout its
July 4th celebration tonight. By 9 PM, the temperatures should cool
to the middle 50s to lower 60s for most of the region, with the
higher elevations remaining significantly warmer (up to the middle
70s). As a reminder, be careful when celebrating the holiday,
especially if your plans involve fireworks or open flames (including
grilling). With the gusty winds and dry conditions inland,
particularly the higher elevations of the East Bay and the Santa
Cruz range, elevated fire weather threats continue into the evening.
One less spark, one less fire!
Low temperatures on Saturday morning drop into the upper 40s to the
middle 50s for the lower elevations and up to the lower 60s for the
highest peaks. A few degrees of warming are possible on Saturday as
the upper level trough erodes, but the overall pattern remains
similar.
&&
.LONG TERM...
Issued at 1209 PM PDT Fri Jul 4 2025
(Saturday night through next Thursday)
Sunday should see a cutoff low splitting from the remnants of the
trough and setting up just off our coastline, leaving temperatures
cooler than the seasonal averages into the early part of next week.
The marine layer will also expand, allowing for further inland
stratus intrusions, while breezy onshore flow continues with a
southerly component, although the wind gusts are not expected to be
as strong as those seen yesterday and today.
The low pressure system weakens and meanders northward late Monday
into Tuesday, allowing an upper level ridge over the Desert
Southwest to build and a warming trend to start. This event looks to
be similar to the previous warm periods we`ve had, where the coastal
regions remain relatively cool while the interior regions heat up.
By the end of the upcoming work week, temperatures near 100 are
possible in the warmest spots, leading to areas of Moderate
HeatRisk, corresponding to a moderate risk for heat-related
illnesses for populations sensitive to heat. Some uncertainty still
remains regarding the evolution of the upper level low and the
evolution of the ridge, so stay tuned as the long range heat
potential is refined through the next few days.
&&
.AVIATION...
(06Z TAFS)
Issued at 945 PM PDT Fri Jul 4 2025
It`s VFR-MVFR, satellite and surface observations show a few
patches of stratus redeveloping in the Bay Area. The SFO-SAC and
ACV-SFO pressure gradients are approx 3 mb each this evening. The
marine layer depth i.e. from sea level to lower level temperature
inversion varies from 1200 to 1800 feet over the Bay Area, to a
somewhat more compressed 1000 feet depth at the Point Sur profiler
(where thermal ridging aloft is stronger). Stratus and fog /IFR-LIFR/
will continue to develop tonight and Saturday morning under nocturnal
radiative cooling to space. Stratus and fog /LIFR-IFR/ will mix out
to the coastline Saturday otherwise VFR is forecast. Onshore winds
prevail during the 06z TAF cycle.
Vicinity of SFO...VFR. West wind easing overnight and Saturday
morning. West wind increasing to 17 gusts to 25 knots Saturday
afternoon and early evening. Forecast models are struggling with
the areal coverage of stratus; for now, it`s a low confidence
stratus ceiling /IFR/ forecast in the 06z TAF for Saturday evening
and night.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...With nocturnal radiative cooling and more
focused lower level cool air advection here tonight and Saturday
morning, this supports redevelopment of stratus and fog /IFR-LIFR/,
timing is mainly after midnight to Saturday morning. Then diurnal
mixing will lift IFR-LIFR to MVFR-VFR by late Saturday morning and
early afternoon. Mainly onshore winds 5 to 15 knots.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 912 PM PDT Fri Jul 4 2025
Fresh to strong northwesterly breezes and moderate seas will
continue through the weekend with winds easing into early next
week. Gale force gusts will be likely near Pt. Sur through Friday
night and again Saturday afternoon. Winds look to increase and
significant wave heights look to build beginning late 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 from 3 PM to 9 PM PDT Saturday for SF Bay N
of Bay Bridge.
Small Craft Advisory from 9 AM to 9 PM PDT Saturday for Mry Bay.
Small Craft Advisory until 3 AM PDT Sunday 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 9 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.
Small Craft Advisory from 9 AM Saturday to 3 AM PDT Sunday 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...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa
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