Port Costa, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

934
FXUS66 KMTR 182134
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
234 PM PDT Sun May 18 2025

...New SHORT TERM, LONG TERM...

.SYNOPSIS...
Issued at 309 AM PDT Sun May 18 2025

Another gusty day today with NW winds 30-40 mph. Elevated fire
weather concerns for far interior areas late tonight and early
Monday with a brief burst of offshore winds. Winds begin to
diminish Monday evening with a warm and dry trend through the rest
of the week.

&&

.SHORT TERM...
Issued at 139 PM PDT Sun May 18 2025
(This evening through Monday)

Key Messages
-Windy northerly flow persists into Monday
-Elevated fire weather concerns in flashier fuels

Blue bird skies blanket the region today. Temperatures are running
a few degrees warmer than yesterday thanks to building high
pressure. The longwave pattern shows the upper level trough that
brought drizzle yesterday is now sweeping through the Four Corners
and high pressure over the EPac is filling in behind it.

This evening through Monday: The aforementioned high pressure
over the EPac will continue to build at the surface and aloft. At
the surface, higher pressure builds along the OR/CA border with
lower pressure inland and southward. This orientation will enhance
the SFO-ACV (N-S) pressure gradient. As such, winds will continue
to increase. We`ve already seen a slight increase in wind speed
since this morning. Hi-res and mesoscale models continue to
advertise a coastal jet setting up just off of Point Reyes this
evening with gusts in the 40-50 kt range. This also corresponds
with the location of our Storm Warning over the coastal waters.
Fortunately, it won`t be that strong over land. However, still
expecting some gusts along the coast and higher terrain. Winds
remain breezy through Monday.

For a fire weather perspective, local WRF model continues to show
a shift of winds to N to NE over the North and East Bay at 2,500
ft. While this direction will usher in some drier air predicted RH
values do no reach critical levels. However, given the finer fuels
(like grass) there are some concerns of rapid spread if a fire
were to start.



&&

.LONG TERM...
Issued at 230 PM PDT Sun May 18 2025
(Monday night through next Saturday)

Key Messages
-Warming and Drying trend through midweek
-Moderate HeatRisk interior locations Wednesday

Winds will finally ease and the N-S pressure gradient begins to
relax Monday night into Tuesday. The warming and drying trend
will continue through at least Wednesday. Each day temperatures
will warm and additional five degrees. Minor HeatRisk will be
possible for much of the region Tuesday and Wednesday with pockets
of Moderate HeatRisk on Wednesday for far interior locations and
the city of San Jose. Those HeatRisk values translate to max
temperatures for 80s to mid 90s. Onshore flow will keep
coastal/bay shoreline areas in check with max temperatures in the
60s and 70s.

A breakdown of the ridge by Thursday will kick off a gradual
cooling trend that will last into next weekend. Simply put, a
little bit of a temperature roller coaster ride this week.


&&

.AVIATION...
(18Z TAFS)
Issued at 1111 AM PDT Sun May 18 2025

VFR conditions will prevail through the forecast period. Winds will
gradually pick up later this afternoon and become more northerly
thanks to a change in the upper level pattern. Gusts should
generally be around 20-30kt for most interior TAF sites, with winds
briefly decreasing for a portion of the overnight hours and then
picking back up late Monday morning or afternoon. Medium confidence
in wind timing.

Vicinity of SFO...The main forecast concern through the TAF cycle
will be the onset of breezy winds. These are expected to kick up
later this afternoon which will then hold through the evening and
early overnight hours before picking back up again Monday afternoon.
Until then, winds of less than 10kt are expected. VFR conditions
prevail through the TAF cycle.
.

SFO Bridge Approach...Similar to SFO. Webcams around the Bay show
some haze, though reporting stations put visibility at P6SM.

Monterey Bay Terminals...VFR conditions at KMRY and KSNS this
morning, with satellite showing  some lingering stratus of the
Monterey Peninsula. Expect VFR conditions to continue, with an
uptick in westerly to northwest winds this afternoon and evening.
Winds decrease gradually after sunset and become southwesterly.

&&

.MARINE...
(Today through Friday)
Issued at 912 AM PDT Sun May 18 2025

Near gale northerly breezes with severe gale are expected, with
storm force gusts expected for the northern waters later this
afternoon. Hazardous marine conditions will persist Monday
through Thursday with strong northerly breezes with near gale
force gusts and rough to very rough seas.

&&

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

     Small Craft Advisory from 3 PM to 9 PM PDT Monday for SF Bay N
     of Bay Bridge.

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

     Small Craft Advisory from 9 AM to 9 PM PDT Monday for Mry Bay.

     Gale Warning until 3 PM PDT this afternoon for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to
     Pigeon Pt 0-10 nm.

     Gale Warning from 9 PM this evening to 9 PM PDT Monday for Pt
     Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt
     Reyes to Pigeon Pt 0-10 nm.

     Storm Warning until 9 PM PDT this evening for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes to
     Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 PM PDT this afternoon for Pigeon Pt
     to Pt Pinos 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning until 9 PM PDT Monday for Pigeon Pt to Pt Pinos 0-
     10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning until 9 PM PDT Monday for Pigeon Pt to Pt Pinos 10-
     60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...KR
MARINE...KR

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