FXUS66 KMTR 011246
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
446 AM PST Thu Jan 1 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1201 AM PST Thu Jan 1 2026

 - High astronomical tides combined with storm surge will bring
   minor to moderate coastal flooding around high tide through
   Sunday

 - Daily rain likely through early next week 

 - Strong southerly winds expected Friday night

&&

.SHORT TERM...
Issued at 1201 AM PST Thu Jan 1 2026
(Today and tonight)

Light rain continues across the Bay Area as the new year begins.
While the total rainfall over the last 24 hours has been less 
than 1", the troposphere has become totally saturated. The PW was
measured at 1.38" on the 00Z sounding. That's near the daily max,
and in the top 0.3% of December soundings. The low level dry 
layer mentioned yesterday has been eliminated. In fact, the first 
dry layer is in the stratosphere. Despite the anonymously high 
moisture, rain rates were held in check by a lack of lift. We 
haven't had a front move through yet to wring out the sponge. That
will change this morning as an occluded front moves across the 
Bay Area and Central Coast. This will increase the rain intensity,
and brings a slight to moderate chance of thunderstorms. High 
resolution models show the best chance over the Central Coast and 
South Bay around 4-7 AM. After the front moves through showers 
will become more scattered and the clouds will lift and lighten. 
There is a second round of showers possible in the afternoon as 
the instability rises with warmer surface temperatures under the 
new cold air mass. A NAM point sounding at Salinas valid at 11 AM 
shows some instability (41 J/kg surface CAPE), winds backing with 
height(16kt 0-1km shear), and good low level moisture (91% LowRH).
One limiting factor is the high freezing level (7,500+ ft). Most 
of the instability is in the warmer air below this level. This 
will limit the amount of ice in the clouds necessary for static 
electricity build up, significantly hurting the chances for 
thunderstorms to form after the front passes. The other issues is 
drier air behind the front. Most likely we will get a break after 
the morning push of stronger rain, with only isolated to scattered
showers expected for the rest of the day and into Friday.

&&

.LONG TERM...
Issued at 1201 AM PST Thu Jan 1 2026
(Friday through Wednesday)

The mostly dry break now looks like it will continue through the
majority of the day Friday before the main event of the week 
arrives Friday night. A strong cold front will quickly approach 
the coast, with southerly winds increasing to a strong breeze. 
These winds will pump a new round of tropical moisture, this time 
from the SW. With stronger winds and a lifting mechanism from 
FROPA, strong showers and thunderstorms are possible into Saturday
morning. With the stronger forcing, these storms also have a 
marginal chance of hitting severe criteria. Even if storms don't 
produce damaging winds, the synoptic flow will likely bring some 
wind impacts across the cwa. Gusts should reach 40-50 mph along 
the coast and in higher terrain. While not quite as strong as last
week, some tree damage and power outages are expected. Southerly 
winds also produce storm surge thanks to the Ekman Transport. This
surge will combine with the ongoing king tides to bring 
exceptionally high tides on Saturday morning, in particular.

As the cold front passes, the 500 mb temperature will drop from
around -16C to -23C. This will cause lapse rate to steepen, and 
could support deeper convection in the post frontal environment on
Saturday. A reinforcing front is due on Sunday, bringing yet 
another round of heavier rain, but less damaging winds. While the 
rain intensity should start to lighten up next week, the pattern 
remains unsettled through the 8th or 9th.

&&

.AVIATION...
(12Z TAFS)
Issued at 445 AM PST Thu Jan 1 2026

Light to moderate winds are expected through the TAF period. Expect 
mostly light to showers through the morning, with chances reducing 
int the late morning and early afternoon. Winds will stay 
southeasterly to southerly through the day for most sites. Light 
spotty showers return in evening and into the night for the more 
northern TAF sites before exiting into early Friday. CIGS will range 
from IFR-levels in some of the interior valleys to VFR heights in 
the more southern sites. Nearly widespread VFR returns into early 
Friday as the system exits.

Vicinity of SFO...Showers continue to move through the area, causing 
slight reductions in visibilities with IFR/MVFR level CIGs. Expect 
mostly light to moderate easterly winds through the morning before 
winds become more southerly and breezy into the afternoon as CIGs 
scatter. Showers exit in the mid afternoon, but another batch of 
slight chances for scattered light rain arrives in the late evening 
but exit again into the late night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Moderate showers exit into the mid morning, 
with lingering light showers lasting into the afternoon. Expect 
mostly mid-level clouds through the TAF period. Winds stay light to 
moderate through the TAF period and range from southerly to 
southeasterly. Shower chances reduce and exit into the afternoon as 
cloud cover scatters.


&&

.MARINE...
(Today through Tuesday)
Issued at 445 AM PST Thu Jan 1 2026

Breezy and showery conditions linger across the waters. Expect
some reductions in winds into the night, but southerly winds
rebuild into Friday and increase to gale force across most of the
waters. These winds look to last through much of the weekend.
Expect light to moderate rainfall to persist through the weekend,
with a slight chance of thunderstorms early Thursday and again
Friday into Saturday. Rain chances and breezy winds will continue
into the beginning of the next work week.

&&

.BEACHES...
Issued at 859 AM PST Wed Dec 31 2025

Perigean spring tides (King Tides) will impact the region through 
Sunday. This is due to the combination of the full moon on 1/3, 
lunar perigee on 1/1, and perihelion on 1/3. In other words all 
three planetary bodies are lined up and close to each other. In 
addition to the high astronomical tide, the incoming low pressure 
system will bring strong southerly winds, generating some storm 
surge. The combination of these factors will bring minor to 
moderate coastal flooding to the low-lying areas near shorelines 
and tidal waterways during high tide through Sunday. At the San 
Francisco tidal gauge, high tide is expected to be 2.0 ft above 
normal at 8:41 AM Thursday, 2.2 ft above normal at 9:34 AM Friday,
2.2 ft above normal at 10:26 AM Saturday, and 1.8 ft above normal
at 11:18 AM Sunday. These predictions include up to 1 foot of 
storm surge that will enhance the astronomical tide and flooding 
threat. High tide varies up to 90 minutes earlier or later along 
the Pacific Coast and through the San Francisco Bay, respectively.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 2 PM PST Sunday for CAZ006-505-506-
     508-509-529-530.

     Wind Advisory from 1 PM Friday to 1 PM PST Saturday for CAZ006-
     502>505-509-512-515>518-528>530.

PZ...Small Craft Advisory from 3 PM Friday to 3 AM PST Saturday for 
     SF Bay N of Bay Bridge.

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

     Small Craft Advisory from 9 AM Friday to 3 AM PST Saturday for 
     Mry Bay.

     Small Craft Advisory until 3 PM PST this afternoon for Pt Arena 
     to Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 AM to 9 AM PST Friday for Pigeon Pt 
     to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes 
     to Pigeon Pt 0-10 nm.

     Gale Warning from 9 AM Friday to 3 AM PST Saturday for Pigeon Pt 
     to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena 
     to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM this morning to 9 AM PST Friday 
     for Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory until 3 AM PST Friday for Pt Arena to Pt 
     Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning from 3 AM Friday to 3 AM PST Saturday for Pt Arena 
     to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 9 AM PST this morning for Pigeon Pt 
     to Pt Pinos 10-60 NM.

&&

$$

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

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Prepared by Boulder-Creek.com Weather at: Thu Jan 1 08:30:02 PST 2026