345
FXUS66 KMTR 201210
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
510 AM PDT Sun Apr 20 2025

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 1251 AM PDT Sun Apr 20 2025

A slight warming trend will continue through Monday before
cool and cloudy weather returns mid to late week.

&&

.SHORT TERM...
(Today and tonight)
Issued at 1251 AM PDT Sun Apr 20 2025

The Ft. Ord profiler is measuring a relatively deep marine layer
around 2,000 feet. This is keeping widespread stratus across the
lower elevations of the Bay Area and the Central Coast. High dew
points and light winds will likely bring areas of fog across the
region later this morning, especially in the North Bay Valleys. We
are waiting to see the visibility start dropping, but don`t be
surprised if a dense fog advisory is issued in the next few hours.
The skies will clear in the afternoon as the stratus mixes out
and marine layer compresses. Temperatures will reach the mid 70s
in the warmer inland areas, with upper 50s to low 60s along the
coast.

&&

.LONG TERM...
(Monday through Saturday)
Issued at 1251 AM PDT Sun Apr 20 2025

Zonal flow will persist from Monday through Tuesday, with quiet
weather and warmer than normal temperatures expected. High surface
pressure will keep the marine layer compressed to around 500 feet
as 850 mb temps rise to around 14C. This will allow most areas
away from the immediate coast to reach 5-10 degrees above normal.
Many of the warmer areas will have minor HeatRisk. This level is
hazardous only to those extremely sensitive to heat such as the
elderly and those living outside. Decent cooling at night will
allow for some relief if you are able to open a window. A short
wave trough will approach the coast early Wednesday, followed by a
much deeper trough on Friday. This pattern change will bring
cooler, cloudier conditions. There is still a chance for rain late
week, but the probability has decreased quite a bit in the latest
update. Why the change? The trough still has broad support across
the guidance envelope, however the moisture tap looks worse. The
GEFS mean probability of IVT>150 has decreased from 40% to 20%
from the 12Z to 00Z run. There`s still a 0% chance of IVT
exceeding 250 in both the GEFS and ECMWF EPS ensembles. In other
words, the chance for light rain Fri-Sat is decreasing, and there
continues to be no real chance for anything more substantial.

&&

.AVIATION...
(12Z TAFS)
Issued at 510 AM PDT Sun Apr 20 2025

Widespread MVFR CIGS are affecting the region with LIFR/IFR CIGS
affecting the North Bay terminals as well as MRY and LVK. Pockets of
fog are also affecting some of the valleys, and look to build around
STS. Cloud cover begins to erode in the late morning, but remains on
the coast, with HAF going scattered into the mid afternoon. Winds
stay light to moderate through the morning, and increase into the
afternoon before reducing again over the evening. IFR CIGS build
along the coast and around the Monterey Bay in the evening. HAF,
SNS, and MRY will see IFR CIGs turn LIFR with pockets of fog into
the later night while the North Bay terminals begin to see fog and
low CIGs form into early Monday.

Vicinity of SFO...Light winds and MVFR CIGS linger into the late
morning. Skies clear before moderate west winds build for the
afternoon. These winds will reduce overnight but remain westerly.
Low clouds look to move through portions of the SF Bay in the early
morning on Monday, but don`t look to fill over SFO.


SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR CIGS and light winds last into the late
morning before CIGs retreat back into the Monterey Bay and moderate
northwest winds build. Winds reduce into the early night as IFR CIGs
move inland and fill over the terminals. Pockets of fog look to form
in the later into the night as CIGs fall to LIFR levels.

&&

.MARINE...
(Today through Friday)
Issued at 510 AM PDT Sun Apr 20 2025

Breezy to gusty north/northwest winds are building in the norther
waters along with building north swell. Winds look to increase and
spread across the outer waters into the work week. The gusty
northerly winds look to become more widespread into the mid week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Monday
     for Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 3 PM PDT Tuesday for Pt Arena to Pt
     Reyes 10-60 NM.

     Small Craft Advisory from 9 AM this morning to 3 PM PDT Tuesday
     for Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Murdock
MARINE...Murdock

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