Boulder Creek, California Weather Forecast Discussion

548
FXUS66 KMTR 122014
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
114 PM PDT Fri Sep 12 2025
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 112 PM PDT Fri Sep 12 2025
- Drier and slightly warmer weather today and Saturday.
- Much warmer conditions early next week with inland Moderate
   HeatRisk possible.
&&
.SHORT TERM...
Issued at 112 PM PDT Fri Sep 12 2025
(This evening through Saturday)
Stratus lingers across the coastal regions, with the inland areas
mostly clear save some fair weather cumulus on the ridgelines of the
interior mountains. The upper level low that brought us the cooler
temperatures and showers has started to move off to the east, behind
which a narrow but stout ridge is building into the West Coast. This
is resulting in a warming and drying trend through the weekend, with
high temperatures today ranging from the upper 70s to the middle
80s, up to the upper 80s to the lower 90s in the warmest spots, the
lower to middle 70s near the Bays, and the middle to upper 60s at
the Pacific coast. Stratus will expand inland overnight, before
retreating to the coast again on Saturday morning. Highs on
Saturday will be similar to today`s.
&&
.LONG TERM...
Issued at 112 PM PDT Fri Sep 12 2025
(Saturday night through next Thursday)
The ridge erodes on Sunday with the passing of an upper level trough
across the Pacific Northwest, but any cooling effects will be
limited to a couple degrees across the far northern reaches of
Sonoma and Napa County, and there is no rainfall in the forecast.
Ridging returns to the western US on Monday, with highs reaching the
upper 80s to the middle 90s inland. Close to the Bays and the coast,
the temperatures remain rather uncertain, dependent on the strength
of any offshore flow that develops in the region. The current
forecast for Tuesday, currently expected to be the warmest day of
the next week, has high temperatures reaching the middle 70s to the
middle 80s near the Bays, and the upper 60s to lower 70s along the
Pacific coast. Strong offshore flow can easily add 5 degrees or more
to those readings. Moderate HeatRisk is possible across the inland
valleys into the middle of next week, meaning that a moderate risk
for heat-related illnesses exists for vulnerable populations,
including children, the elderly, pregnant women, people with certain
chronic illnesses, and people working or living outdoors without
adequate shelter or hydration.
From the previous forecaster: Next Thursday and beyond get pretty
interesting on the long range forecast. Kind of fantasy land at this
point, but there are signs we`ll need to watch for another round of
tropical/monsoonal moisture surge. It`s too early for details, but
longer range global ensembles/cluster show transport flow that would
bring decaying tropical system moisture with a hint of monsoonal.
GFS model for instance handled the early September lightning event
better than others. It`s fantasy land picture for the 19-20th of
Sept shows showers and thunderstorms over Central California. At
this point, it worth keeping and eye on. Timing would be bad from a
fire weather stand point as warmer weather develops over the weekend
and peaks early next week.
&&
.AVIATION...
(18Z TAFS)
Issued at 1052 AM PDT Fri Sep 12 2025
A mix of IFR/MVFR conditions this morning with a moderate to high
probability of VFR expected to return to the Bay Area terminals by
this afternoon. Lower confidence for the Monterey Bay terminals
where MVFR ceilings have a moderate (30-60%) probability of
lingering through much of the day, however still expected a few
hours of VFR conditions to return in the current TAFs. Onshore winds
increase this afternoon and ease late this evening and more so into
Saturday morning. Moderate to high confidence for IFR/MVFR late this
afternoon or early evening across the Monterey Bay terminals and
MVFR returning late this evening for the Bay Area terminals.
Ceilings potentially lower to LIFR around the Monterey Bay terminals
and IFR for the Bay Area Terminals early Saturday morning before
lifting by Saturday afternoon. Onshore winds increase once again
Saturday afternoon.
Vicinity of SFO...MVFR/VFR ceilings currently with a high confidence
of improving to VFR by late morning or early afternoon. Onshore
winds increase this afternoon and begin to ease into Saturday
morning. Moderate to high confidence for an early return to MVFR
late this evening, potentially (lower confidence) lowering to IFR
early Saturday morning. Ceilings will then lift mid-to-late morning
across the region, however moderate confidence for MVFR to linger
through 21Z Saturday or potentially longer.
SFO Bridge Approach...MVFR ceilings forecast return later tonight
(generally around or after 06Z) and clear sooner Saturday
morning (between 18Z-20Z). Otherwise, similar to SFO.
Monterey Bay Terminals...There is moderate confidence (30-60%) for
MVFR ceilings to persist through much of the day today (especially
at MRY), however still expected a few hours of VFR conditions to
return in the current TAFs. Onshore winds increase this afternoon
and diminish after sunset. High confidence for an early return late
this afternoon of IFR/MVFR ceilings with a low to moderate potential
for LIFR ceilings early Saturday morning.
&&
.MARINE...
(Today through Wednesday)
Issued at 824 AM PDT Fri Sep 12 2025
Breezy NW winds and fresh gusts are expected today with locally
stronger gusts possible across the northern outer waters and along
the Big Sur coastline. Rough seas persist across the outer waters
while more moderate seas persist across the inner waters. Winds
decrease Saturday as fresh to strong gusts become more localized
across the southern coastal waters. Another round of widespread
fresh to strong NW winds begins Sunday into next week with the
strongest winds located across the far northern outer waters.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 3 AM PDT Saturday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for
     Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas
     0-10 nm.
Small Craft Advisory until 3 AM PDT Saturday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...DialH
LONG TERM....DialH
AVIATION...RGass
MARINE...RGass
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NWS MTR Office Area Forecast Discussion