FXUS66 KMTR 290114
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
614 PM PDT Fri Aug 28 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1253 PM PDT Fri Aug 28 2026

 - Slight chance of rain showers through this afternoon with 
   thunderstorm chances focused on the Central Coast, tapering off
   by this evening

 - Cooling trend continues into early next week

&&

.SHORT TERM...
Issued at 1253 PM PDT Fri Aug 28 2026
(This evening through Saturday night)

Temperatures are struggling to warm to their forecasted maximum 
values this afternoon. This is as abundant mid-to-high level cloud 
cover from remnant moisture from former Tropical Storm Iselle moves 
over the region. However, we are seeing via satellite that breaks in 
this cloud cover are appearing off of the Central Coast. This may 
result in enough heating to destabilize conditions across this 
region. As such, we are keeping the Red Flag Warning in effect 
through 3 PM this afternoon given the dry lightning potential. 

The mid-to-upper level moisture is forecast to shift eastward into 
the Sierra Nevada as the trough off of the Pacific Northwest coast 
deepens. Thus, rain showers and the potential for thunderstorms 
greatly diminishes after sunset. However, the aforementioned trough 
will result in a deepening of the marine layer tonight and into the 
upcoming weekend. Therefore, an increased probability of stratus near 
the coast and into the adjacent valleys overnight tonight. 

Slightly warmer temperatures are expected on Saturday as low clouds 
that do develop overnight retreat back to the coastline by tomorrow 
afternoon and give way to mostly sunny skies across the interior. 

&&

.LONG TERM...
Issued at 1253 PM PDT Fri Aug 28 2026
(Sunday through next Thursday)

A reinforcing trough deepens off of the Pacific Northwest coast by 
Monday, allowing afternoon temperatures to be some 5 to 15 degrees 
below seasonal averages. Beyond Monday and Tuesday, the latest 
guidance indicates troughing off of the West Coast will be stronger 
than previous anticipated. Therefore, less likely to see tropical 
moisture from the Eastern Pacific to advect northward. However, 
confidence remains low at this time. Be sure to keep up to date with 
the latest forecast information from a trusted and reliable 
source.

&&

.AVIATION...
(00Z TAFS)
Issued at 614 PM PDT Fri Aug 28 2026

It's VFR except for patchy stratus /MVFR-IFR/ along the immediate
coastline from coastal Marin County to coastal San Mateo County. 
Mid to upper level clouds and lingering showers will move eastward
away from the forecast area this evening. The mid-latitude wind 
flow pattern returns with drying air tonight and Saturday. The 
GFS shows precipitable water quickly lowering tonight and Saturday,
near the 10th percentile on Oakland upper air soundings for late 
August. With decreasing water vapor this will result in radiative 
cooling and with lingering boundary layer moisture it is likely to
cool to saturation resulting in areas of fog and stratus /IFR-LIFR/.
Diurnal surface warming will mix out fog and stratus improving 
conditions to MVFR-VFR by late Saturday morning and afternoon.

Vicinity of SFO...VFR until tempo stratus /MVFR/ 04z-08z tonight,
then stratus /MVFR/ prevailing tonight to 18z Saturday morning. 
Thereafter VFR is forecast Saturday afternoon and evening. West 
wind near 15 knots tonight decreasing to 8 to 10 knots late tonight
and Saturday morning. West wind increasing to 15 to 25 knots 
Saturday afternoon and evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR then tempo stratus /IFR-LIFR/ tonight
and Saturday morning. Surface warming will mix out stratus by late
Saturday morning and afternoon. West to northwest winds 5 to 15
knots.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 509 PM PDT Fri Aug 28 2026

Fresh northwest breezes with occasional near gale force gusts
continue through the weekend as well as a long period southerly
swell. The long period southerly swell peaks on Saturday around 17
to 18 seconds and gradually diminishes by Sunday night. Wind
driven seas briefly build to rough Saturday afternoon into Sunday
and gradually subside to moderate through next week.

&&

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

     Small Craft Advisory until 9 AM PDT Sunday for Pigeon Pt to Pt 
     Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt 
     Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PDT Sunday for Pigeon Pt to Pt 
     Pinos 0-10 nm.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa
MARINE...Navarrete

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Prepared by Boulder-Creek.com Weather at: Fri Aug 28 18:30:02 PDT 2026