FXUS66 KMTR 281954
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1254 PM PDT Fri Aug 28 2026
...New SHORT TERM, LONG TERM, FIRE WEATHER...
.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...
(18Z TAFS)
Issued at 1123 AM PDT Fri Aug 28 2026
VFR across all terminals, except for HAF where it will remain IFR
until the early afternoon. Gentle to moderate onshore winds increase
through the day and ease overnight. High level clouds associated
with a moisture plume persist and gradually decrease this
evening. Drizzle/light rain is being measured across the region
which is expected to continue into the early afternoon as well.
As the moisture remnants continue on their eastward track out of
our region, the marine layer will begin to build back to its usual
pattern. There is currently low confidence on how widespread and
organized it will be tonight as the stratus feed looks patchy on
satellite to our northwest. Rather than locking in IFR to MVFR
ceilings, the TAF hints at the possibility with SCT decks. High
confidence for coastal sites to develop IFR ceilings later this TAF
period, though the exact timing is uncertain.
Vicinity of SFO...Moderate northwest winds persist through the
afternoon with some light rain nearby the terminals. Onshore winds
ease through the evening with low confidence for MVFR ceilings to
develop around midnight.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...VFR with gentle northwest breezes through
the day. The potential for light rain near the airports persists
this afternoon and gradually diminishes by sunset. Overnight, winds
become more west to southwest, but remain light. Medium confidence
for IFR ceilings to develop with an arrival around midnight.
&&
.MARINE...
(Today through Wednesday)
Issued at 957 AM PDT Fri Aug 28 2026
Fresh to strong northwest breezes persist through the weekend and
diminish to moderate by the beginning of the week. A long period
southerly swell peaks on Saturday around 17 seconds and gradually
subsides by the end of the weekend. Moderate wind driven seas
persist into next week.
&&
.FIRE WEATHER...
Issued at 1253 PM PDT Fri Aug 28 2026
A Red Flag Warning remains in effect through 3 PM for dry lightning
potential across the Santa Cruz Mountains and Central Coast. Refer
to the Short Term section for more details.
RGass
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until 3 PM PDT this afternoon for CAZ512-516-
517-528>530.
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...Navarrete
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Fri Aug 28 14:30:02 PDT 2026
From the National Weather Service
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