988
FXUS66 KMTR 192103
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
203 PM PDT Thu Jun 19 2025
...New SYNOPSIS, SHORT TERM, LONG TERM, FIRE WEATHER...
.SYNOPSIS...
Issued at 202 PM PDT Thu Jun 19 2025
Temperatures below seasonal averages persist through the weekend.
Gusty winds and low daytime humidities lead to elevated fire weather
conditions in the interior. Seasonal conditions resume early next
week.
&&
.SHORT TERM...
(This evening through Friday)
Issued at 202 PM PDT Thu Jun 19 2025
Satellite imagery reveals stratus clouds lingering across the
western San Mateo Peninsula and patches of the Monterey Peninsula.
These patches of cloud may be slow to mix out this afternoon, and
some inland stratus development is possible tonight through Friday
morning. A developing upper level low off the coast of British
Columbia is approaching the Pacific Northwest, with an associated
cold front cooling temperatures across the region by as much as 10
degrees compared to this time yesterday. Highs will reach the middle
70s to lower 80s in the inland valleys, the lower to middle 90s in
the southern reaches of Monterey and San Benito counties, the 60s
along the Bayshore, and the middle 50s to lower 60s along the
Pacific coast. Coastal drizzle is possible tonight into Friday
morning, with low temperatures generally in the middle 40s to the
middle 50s. Friday`s high temperatures will generally be similar to
today`s with further cooling in the inland valleys of the North Bay
and Central Coast, with high in the upper 60s to the middle 70s
across the inland valleys and the lower to middle 80s in the
southern reaches of Monterey and San Benito Counties.
The deepening upper level low to the north is causing a tightening
of the pressure gradient across the region, leading to strong and
gusty northwest winds developing through the day and lasting into
Friday. Gusts for this afternoon and evening will reach 25 to 40 mph
across the region, with the highest gusts along the coast, across
the ridgelines, through the gaps and passes, and within the Salinas
Valley. Particularly favored locations such as the Altamont Pass and
favored locations in the Salinas Valley may get gusts up to 50 mph
this afternoon and evening.
&&
.LONG TERM...
(Friday night through next Wednesday)
Issued at 202 PM PDT Thu Jun 19 2025
The strong gusts will continue into Saturday with the winds expected
to peak Friday evening. Through the weekend, the low pressure system
will begin to split, thus slackening the pressure gradient, with
some of its energy moving off into the Canadian prairie provinces,
leaving behind a more open trough across California. This open
trough will stick around for a few days with a strong upper level
ridge over the eastern United State blocking its path to the due
east. As a result, there will be a gradual warming trend into the
early part of next week, but nothing resembling a heat wave is
expected, with the high temperatures generally around seasonal
averages of the lower to middle 80s inland and the upper 60s to the
middle 70s along the Bayshore, while cooler conditions continue
along the Pacific coast with highs temperatures in the upper 50s to
middle 60s.
&&
.AVIATION...
(18Z TAFS)
Issued at 1035 AM PDT Thu Jun 19 2025
A few morning clouds, but they have all but faded for the most
part. Half Moon Bay on the other hand is doing Half Moon Bay
things...it`s still cloudy. The bigger story for today will be the
tightening onshore gradient from SFO-SAC leading to gusty onshore
flow and a mixed lower atmosphere. AWW remains for SFO with gusts
GT 35kts. Tonight is a lower confidence forecast as onshore flow
eases ever so slightly allowed for a mix marine layer with a few
cigs. Will bring in some cigs late, but expect another early
clearing tomorrow.
Vicinity of SFO...VFR through late tonight. Winds gradually ramp
up through 19-20Z before peaking after 22Z. 35kt seems like a safe
bet, but 40kt would be the upper end at 20% chc. Will bring in a
few cigs late tonight into Friday am. About 40-50% chc on cigs
below 5k feet. Will likely need another AWW for Friday.
SFO Bridge Approach...Less likely for cigs tonight.
Monterey Bay Terminals...VFR through this afternoon. Cigs return
this evening as sun begins to set. MVFR cigs tonight into Friday
AM.
&&
.MARINE...
(Today through Tuesday)
Issued at 854 AM PDT Thu Jun 19 2025
A cold front pushed through the region overnight. Behind the front
widespread gale force winds have developed over the coastal
waters. Winds ease from gale force to near gale force late Friday
into Saturday persisting into early next week. Winds will be
strongest across the outer waters and for the inner coastal waters
north of Point Reyes and south of Point Sur, where coastal jets
are expected to develop. Significant wave heights build to 10 to
12 feet across the coastal waters Thursday into the weekend before
abating early next week.
&&
.FIRE WEATHER...
Issued at 202 PM PDT Thu Jun 19 2025
Elevated fire weather conditions are setting up today across the
interior, with widespread RH values below 30% observed across the
interior of the East Bay south through the Gabilan Range, along with
the Santa Lucia mountains, combined with gusts of 20 to 25 mph.
Gusts are expected to increase to 25 to 40 mph across the interior
later this afternoon and evening, with strong gusts resuming Friday
and Saturday afternoon. Brief periods of critical fire weather
conditions are possible with daytime relative humidities of 15 to
25% in the interior. However, continuing marine layer influence,
especially during the night, and the fact that winds remain onshore,
mean that widespread critical fire conditions do not develop across
the district. Gusty winds begin to subside on Saturday, but the
upper level pattern will lead to more northerly winds developing
across the region. As with today`s fire weather threat, widespread
critical fire weather conditions are not expected within the
district, although the fire weather threat will increase for areas
closer to the Central Valley. The fire weather threat will continue
to diminish Sunday into the early part of next week with the gusty
winds further relaxing, although humidity values in the interior
will be slow to rise.
DialH
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Friday for Mry Bay-SF Bay N
of Bay Bridge.
Small Craft Advisory from 1 PM to 9 PM PDT Friday for Mry Bay-SF
Bay N of Bay Bridge.
Gale Warning until 9 PM PDT Friday for Pigeon Pt to Pt Pinos 0-
10 nm-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-Pt Reyes to
Pigeon Pt 0-10 nm.
Gale Warning until 3 PM PDT Friday for Pigeon Pt to Pt Pinos 10-
60 NM.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM
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