486
FXUS66 KMTR 210417
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
917 PM PDT Fri Jun 20 2025
...New UPDATE, MARINE...
.SYNOPSIS...
Issued at 1257 PM PDT Fri Jun 20 2025
Seasonably cool temperatures through this weekend with windy
conditions. Elevated fire weather concerns continue into Sunday
morning as gusty winds combine with dry conditions. Return to
normal temps and quiet conditions by early next week.
&&
.UPDATE...
Issued at 917 PM PDT Fri Jun 20 2025
It has been a windy day across the Bay Area with SFO notably gusting
to 53 mph at 7:56 PM this evening. Winds will remain gusty overnight
before peaking Saturday morning/afternoon. The overall forecast
remains on track with winds set to diminish Sunday into next week as
an upper level trough moves eastward. In terms of fire weather,
daytime relative humidity values dropped into the teens to 20s
across the North Bay Interior Mountains and interior Central Coast.
Fire weather conditions will remain near critical through Saturday
across the higher elevations of the North Bay Interior Mountains,
Interior Central Coast, and East Bay Hills as gusty winds and dry
conditions continue.
&&
.SHORT TERM...
(This evening through Saturday)
Issued at 1257 PM PDT Fri Jun 20 2025
Mostly clear skies across the region today a gusty NW winds ramp
up. Current winds gusting in the 25-35 mph range across some of
the more wind-prone gaps and passes. Most notably up to about 40
mph at Altamont. Winds are expected to remain gusty through
tonight as a deep upper low digs into the Great Basin. Due to the
positioning of the low and juxtaposition of the upper level jet,
winds will largely remain onshore through the event, which is a
bit of a silver lining, keeping the marine layer moisture present
below about 2000 feet. For areas above the marine layer, very dry
afternoon RH and limited overnight recovery will present an
elevated fire weather threat thanks to dry grasses and shrubbery.
&&
.LONG TERM...
(Saturday night through next Thursday)
Issued at 1257 PM PDT Fri Jun 20 2025
The peak of the winds looks to be Saturday during the early
morning hours, but gusty conditions will linger through into
Sunday morning. Towards the end of the event Monday morning,
there is a small chance that the winds make a turn towards a more
offshore direction, but by the time the surface pressure gradient
supports this, much of the upper level support from the system
will have moved on. Therefore, we aren`t expecting any offshore
wind component Monday morning to have much more than a very minor
impact as of this forecast issuance. For the rest of the period, a
more "normal" pattern is restore as a ridge builds over our region
and subtle troughing to the north subdues any substantial
warming. Thus, we return to seasonable temperatures and relatively
quiet conditions next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 516 PM PDT Fri Jun 20 2025
VFR through the TAF period. Stronger winds last into the night before
reducing. Winds along the coast will still be breezy and gusty,
while surface winds in more inland areas become more moderate.
However, winds aloft will remain strong, causing LLWS concerns,
specifically at STS, which will have strong winds at 1000 ft AGL.
Winds aloft and at the surface reduce further into Saturday morning,
but stay breezy along the coast. Winds build across the region again
into Saturday afternoon, but do not look to be as strong as the
current winds.
Vicinity of SFO...VFR through the TAF period. Strong and gusty west
winds last into the night before reducing by 10 kts in both winds
and gusts. Expect gusts to cut off and winds to reduce slightly into
early Saturday, keeping winds moderate through the morning and into
the early afternoon. Gusty winds return for Saturday afternoon with
around 30 kt gusts on top of 24 kt winds. These winds and gusts
reduce into the early night.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR through the TAF period. Breezy and
gusty winds last into the night before reducing, becoming moderate
for MRY, but still seeing some southwest breezes at SNS. Cloud cover
looks to form just outside of MRY in the late night and early
morning to the south and east, but does not look to fill over MRY.
Skies clear into the mid morning.
&&
.MARINE...
(Tonight through next Thursday)
Issued at 917 PM PDT Fri Jun 20 2025
Strong gusts and rough seas are producing hazardous marine
conditions continue through the first half of Sunday before winds
reduce. Seas look to be slower to ease but will improve into the
next work week. Breezy but less strong winds linger for the first
part of the next work week as well.
&&
.FIRE WEATHER...
Issued at 323 AM PDT Fri Jun 20 2025
Elevated fire weather conditions continue today across the
interior becoming more widespread on Saturday, with RH values
around 30% expected across the interior of the East Bay south
through the Gabilan Range, along with the Santa Lucia mountains
this afternoon. Gusty winds above the marine layer and elevated
interior locations will once again be around 25 to 40 mph with
less coverage today than Thursday. 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
somewhat on Saturday, but the upper level pattern will lead to
more northerly winds developing across the region. As with
Thursday`s fire weather threat, widespread critical fire weather
conditions are not expected within the district, although the fire
weather threat will increase once again 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.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Mry Bay-SF Bay N
of Bay Bridge.
Gale Warning until 3 AM PDT Sunday for 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.
Gale Warning until 3 AM PDT Saturday for Pt Reyes to Pigeon Pt 0-
10 nm.
Gale Warning from 3 PM Saturday to 3 AM PDT Sunday for Pt Reyes
to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PDT Saturday for Pigeon Pt to Pt
Pinos 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Gale Warning from 9 AM Saturday to 3 AM PDT Sunday for Pigeon Pt
to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Behringer
LONG TERM....Behringer
AVIATION...Murdock
MARINE...Murdock
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