Pleasanton, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

173
FXUS66 KMTR 210451
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
951 PM PDT Tue May 20 2025

...New AVIATION...

.SYNOPSIS...
Issued at 244 PM PDT Tue May 20 2025

Elevated fire weather concerns through Thursday, which will be
accompanied with strong and gust northwesterly winds and above
normal seasonal temperatures. A pattern change happens late in the
week which will bring cooler temperatures for Friday, with
temperatures gradually warming over the weekend.

&&

.UPDATE...
Issued at 909 PM PDT Tue May 20 2025

Skies remain clear across the region this evening. Dry conditions
persist under the upper level ridge, with the Fort Hunter Liggett
RAWS site reporting a minimum relative humidity of 8%, while a
couple of sites on Highlands Peak near Lucia are currently seeing
relative humidity values drop to the single digits as well
offshore flow creates a nocturnal drying effect. With even warmer
temperatures expected tomorrow (the warmest spots in the interior
reaching the low to middle 90s), the elevated fire weather
concerns continue tomorrow, especially for the finer fuels such
as bushes and grasses.

DialH

&&

.SHORT TERM...
(This evening through Wednesday)
Issued at 244 PM PDT Tue May 20 2025

Key Messages

-Elevated fire weather concerns
-Breezy north to northwest winds
-Above normal seasonal temperatures

Upper level dynamics become more lean more zonal with minor signs of
weak ridging. At the surface, we remain nestled between low pressure
to our east and high pressure to our west leading to a tighter
pressure gradient overhead. Breezy north to northwest winds look to
persist through the period; however, warmer high temperatures and
drier air is on tap for Wednesday. The elevated fire weather
concerns will continue for finer fuels such as brush and grass,
especially for interior regions.

&&

.LONG TERM...
(Wednesday night through next Monday)
Issued at 244 PM PDT Tue May 20 2025

Key Messages

-Elevated fire weather concerns through Thursday
-Breezy north to northwest winds
-Cooler temperatures Thursday and Friday, seasonal temperatures
return

An upper level trough swings through the PacNW on Thursday, which
will bring slightly cooler weather to the region. A fairly dry day
is still on tap, in terms of RH and no rain, with improving RH
overnight. A secondary, and more broad upper level wave approaches
the west and Central Coast for Friday, which will bring the coolest
temperatures of the week. Upper level ridging looks to quickly fill
behind it, leading to the return seasonal temperatures.

&&

.AVIATION...
(06Z TAFS)
Issued at 951 PM PDT Tue May 20 2025

The marine layer depth to the lower level temperature inversion
varies from approx 700 feet to 1400 feet. Drier to much drier air
is in the atmospheric mix within the gusty northwest winds along
the coast, resulting in VFR. Gusty northwest winds are otherwise
resulting in haze/hazy conditions due to sea spray/salt condensation
nuclei lofted into the marine layer.

The northerly ACV-SFO pressure gradient is 7.4 mb, the onshore
gradient SFO-SAC is 2.7 mb. Dry air tonight and Wednesday will
have a good chance of continuously mixing into the marine layer
i.e. the boundary layer helping to keep VFR going, except the
immediate coast may see a patch or two of stratus and/or fog late
at night and/or early morning. Otherwise VFR is forecast Wednesday.
Gusty west to northwest winds developing Wednesday afternoon and
evening.

Vicinity of SFO...VFR. West wind 5 to 15 knots tonight and
Wednesday morning. West wind with gusts increasing to near 30
knots Wednesday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Moderate to high confidence VFR continues
through late evening, then low to moderate confidence VFR forecast
late tonight and Wednesday morning. Plenty of dry air is arriving
from the north at and above the marine layer temperature inversion,
since dry air is molecularly heavier than water vapor the current
near term weather pattern may just help extend VFR here along the
coastline through late tonight and Wednesday morning. Otherwise VFR
Wednesday. West winds 5 to 10 knots tonight and Wednesday morning,
increasing to 10 to 20 knots Wednesday afternoon and early evening.

&&

.MARINE...
(Tonight through next Monday)
Issued at 909 PM PDT Tue May 20 2025

Strong northwesterly winds and hazardous seas will continue over
the coastal waters tonight through late week. Westerly winds will
become gusty over the bays each afternoon and evening. Winds will
diminish and seas will subside gradually into the upcoming
weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Mry Bay.

     Gale Warning until 3 AM PDT Wednesday for Pigeon Pt to Pt Pinos
     0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt
     0-10 nm.

     Gale Warning until 9 AM PDT Wednesday for Pt Pinos to Pt Piedras
     Blancas 0-10 nm.

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

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Canepa
MARINE...Canepa

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