Big Basin, California Weather Forecast Discussion

115
FXUS66 KMTR 141600 AAA
AFDMTR
Area Forecast Discussion...UPDATED
National Weather Service San Francisco CA
900 AM PDT Sun Sep 14 2025
...New KEY MESSAGES, UPDATE, MARINE...
.KEY MESSAGES...
Updated at 900 AM PDT Sun Sep 14 2025
- Temperatures around or slightly below normal today
- Much warmer temperatures for the first half of the upcoming
   work week with Moderate heat risk through Wednesday
- Late week pattern change
&&
.UPDATE...
Issued at 900 AM PDT Sun Sep 14 2025
The short term forecast is in good shape, with just some minor
alterations to weather/sky grids to account for trends. Satellite
imagery illustrates patchy marine stratus across the coastal region
this morning, particularly along the Pacific side of the SF
Peninsula, East Bay Shoreline, and southern Salinas Valley. The
greatest potential for patchy fog resides across SF and southward
along CA HWY 1 through to regions near/north of Davenport in Santa
Cruz County. I anticipate mostly sunny skies by later this
afternoon, the the exception being across the Pacific coast along
the SF Peninsula. Otherwise, gusty winds near 30 mph through some
of the gaps and passes will persist through today, especially with
the afternoon sea-breeze kicking in.
Otherwise, the remainder of the forecast remains unchanged and
we`ll provide more details on this week`s heat and high-based
convection potential later this morning/early this afternoon.
&&
.SHORT TERM...
Issued at 256 AM PDT Sun Sep 14 2025
(Today and tonight)
A weak cold front under quasi-zonal flow in the wake of progressive
ridging that has shifted east of our area will keep temperatures
close to or slightly below normal today, and similar to yesterdays
max temperatures. Stratus coverage early this morning is not as
extensive as previous couple nights, as a drier airmass gradually
sets in over our area ahead of the warmer temperatures expected
to begin the new work week. Stratus development will be even more
limited this evening into Monday morning as drier air continues to
mix down from mid-levels closer to the surface.
&&
.LONG TERM...
Issued at 256 AM PDT Sun Sep 14 2025
(Monday through Saturday)
Above normal temperatures arrive Monday with an amplified ridging
pattern over western CONUS. Just a couple of days ago, model
guidance suggested the potential for a more impactful heat event for
the first half of the upcoming work week. Better consensus in
deterministic guidance is now providing a clearer picture for max
temperatures to peak Tuesday (although only slightly cooler on
Wednesday). H85 temps jump into the 75th percentile (18C-19C) Monday
afternoon, then up to the 95th percentile (21C-22C) for Tuesday and
Wednesday as the ridge pivots east across the Pacific Northwest.
High temperatures Tuesday and Wednesday will run roughly 10 to 15
degrees above normal across the interior, especially the East Bay
Hills, South Bay, Santa Cruz mountains and southern Monterey
County. By late Wednesday, a deepening trough to our north and a
weak upper level low just offshore begin a pattern shift that
becomes more unsettled as we head toward late week into next
weekend.
&&
.AVIATION...
(12Z TAFS)
Issued at 428 AM PDT Sun Sep 14 2025
Very discontinuous stratus pattern this morning resulting in high
than normal uncertainty for Bay Area and Central Coast terminals.
Clearing skies for North Bay terminals resulting in local FG
impacts that will likely linger until just after sunrise.
We should see a clearing of stratus around the Bay Area followed
by a slight chance for redevelopment around sunrise. Otherwise VFR
with a higher likelihood of VFR overnight tonight when compared
to last night.
Vicinity of SFO...Currently VFR as of writing, but high res
guidance is advertising a patchy stratus redevelopment invof
KOAK/KSFO around sunrise before quickly mixing out to VFR once
again. This is the main reason for uncertainty this morning.
Beyond that, high confidence in VFR into this evening.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Ample clearing overnight has led to
patchy dense fog development invof the Monterey peninsula and
northern Salinas Valley. Currently anticipating these impacts to
last into the morning hours, at least in the form of IFR stratus.
Relatively short VFR window today before MVFR cigs fill back in
the the 00Z hour. However, this is a lower-than-normal confidence
scenario. Hi res guidance has been advertising another round of
very localized clouds into Monday morning.
&&
.MARINE...
(Today through Friday)
Issued at 900 AM PDT Sun Sep 14 2025
A gentle to moderate northwesterly breeze will persist across the
region through much of the forecast period, easing by Friday of
the upcoming week. Fresh to strong gusts will be possible in the
favored coastal jet regions and across the offshore zones through
Monday creating hazardous conditions for small craft. Moderate
seas persist, especially offshore and will subside through midweek
before building again late week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this
     evening for Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Monday
     for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60
     NM.
Small Craft Advisory until 3 AM PDT Monday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.
&&
$$
UPDATE...Bain
SHORT TERM...JM
LONG TERM....JM
AVIATION...Behringer
MARINE...RGass
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NWS MTR Office Area Forecast Discussion