FXUS66 KMTR 121300
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
600 AM PDT Tue May 12 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 1216 AM PDT Tue May 12 2026

 - Gradual cooling trend develops today through midweek

 - Warming and drying trend midweek and beyond

&&

.SHORT TERM...
Issued at 1216 AM PDT Tue May 12 2026
(Today and tonight)

The pattern shift discussed on yesterday's AFD is upon us. A quick
snapshot of the longwave pattern over the West shows a ridge
sneaking off to the east and settling over the Desert SW and
knocking on CA is an upstream upper trough and associated cut-off
low. Onshore flow plus lower 500 mb heights equals a deep marine
layer presences this morning. Satellite fog product shows a decent
marine layer with way more inland intrusion than 24 hours ago.
Marine layer depth will vary from 1000-1500 feet this morning.
Light mist or drizzle will be possible along the immediate
coastline through this morning.   

Deeper marine layer and onshore flow will lead to a later 
clearing time of inland stratus for Tuesday. The coast on the 
other hand may not see much in the way of clearing today. 
Noticeable cooldown for Max Temps today bringing readings closer 
to seasonal averages. Max Temps 60s to 70s coast/bays and 70s to 
lower 90s interior. 

If we follow the trend is your friend logic: the upstream upper 
low has been trending more north and continues to do so. As such, 
the chance for widespread drizzle and/or light rain has now been 
removed from the forecast late Tuesday night into Wednesday. That 
being said, still expecting another push of marine stratus 
overnight. 

&&

.LONG TERM...
Issued at 1216 AM PDT Tue May 12 2026
(Wednesday through Monday)

The upper low will sweep through Oregon during the day on
Wednesday. While the forecast has trended drier temperatures will
still be on the cool side. Wednesday will be coolest day of the
forecast. Additionally, expect some breezy onshore winds through
out the day. Winds will be strongest along the coast and inland 
gaps/passes.  

Quiet weather returns for the second half of the work week and 
into the weekend with zonal flow, warming temps, night/morning 
clouds.

&&

.AVIATION...
(12Z TAFS)
Issued at 600 AM PDT Tue May 12 2026

.AVIATION...
The stratus intrusion onshore has brought IFR-LIFR ceilings to most 
terminals which should scatter out by late morning Tuesday. The 
lower cloud ceilings are impacting the visibility at a few airports, 
though are expected to improve by 17Z. Light winds will increase to 
moderate strength by the afternoon with some terminals experiencing 
gusts up to 20-25kts. The marine layer is expected to move back 
onshore by Tuesday evening, though it won't be as expansive.

Vicinity of SFO...Moderate onshore winds will persist through the 
TAF period with gusts reaching up to 25-27 kts Tuesday afternoon. 
The moderate winds combined with high-level clouds should help mix 
out the stratus layer and shift back to VFR conditions by 18Z. The 
stratus deck is expected to return overnight (02-03Z) but should 
remain MVFR through Wednesday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...LIFR ceilings are causing misty conditions 
which is impacting the visibility across the terminals this morning. 
Conditions are expected to improve by 16-18Z with VFR conditions 
forecast by 19Z. Light, variable winds are expected to become 
moderate and onshore by the afternoon. Another night of stratus is 
also anticipated to return by Wednesday evening. 

&&

.MARINE...
(Tonight through next Sunday)
Issued at 949 PM PDT Mon May 11 2026

Occasional strong gusts continue through tonight across the far
northern outer waters. Otherwise, a moderate to fresh northwest
breeze will continue over the waters through midweek. Seas subside
but remain moderate with 4 to 6 foot seas through midweek. Winds
increase and seas build starting mid-week with gale force winds
and wave heights in excess of 10 feet likely starting Friday and
continuing through the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 3 PM PDT Wednesday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 
     NM-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 3 PM this afternoon to 3 PM PDT 
     Wednesday for Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to 
     Pigeon Pt 0-10 nm.

     Small Craft Advisory from 3 AM to 3 PM PDT Wednesday for Pt 
     Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Navarrete
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Tue May 12 06:30:03 PDT 2026