Petaluma, California Weather Forecast Discussion

351
FXUS66 KMTR 141004
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
304 AM PDT Sun Sep 14 2025
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 256 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
- Moderate HeatRisk possible inland Monday through Wednesday
- Late week pattern change
&&
.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...
(21Z TAFS)
Issued at 125 PM PDT Sat Sep 13 2025
KSFO and KOAK continue to see MVFR conditions early this afternoon
as well as KMRY and KSNS. We have a moderate probability for a
few hours of clearing later this afternoon before IFR/MVFR
conditions return. However, the far interior areas of the region
returned to VFR as of late morning.
Onshore winds will increase before easing after sunset and more
so into Sunday morning. Generally moderate confidence for IFR/MVFR
conditions to return late afternoon across the Monterey Bay
region and late evening across the Bay Area terminals. The HRRR
shows little indication of low ceilings returning, especially over
the Bay Area terminals. However, other guidance including the
LAMP shows a return in the aforementioned timeframe. This is
likely due to a dry frontal boundary approaching from the north
late tonight into Sunday morning.
Vicinity of SFO...High confidence for onshore winds to increase this
afternoon before easing into early Sunday morning. Moderate
confidence for MVFR conditions to return late this evening and
persist into mid-morning on Sunday. Low confidence for sub-MVFR
conditions early Sunday morning. Earlier clearing is expected Sunday
morning between 16Z-18Z as the marine layer becomes mixed out by the
approaching dry frontal boundary. Onshore winds increase once again
Sunday afternoon.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Moderate confidence for VFR conditions
to return briefly this afternoon with increasing onshore winds.
Moderate confidence for IFR/MVFR ceilings return late afternoon
and persist through the night as winds ease.
&&
.MARINE...
(Tonight through next Friday)
Issued at 935 PM PDT Sat Sep 13 2025
Northwesterly winds are forecast to increase Saturday afternoon
with fresh to strong breezes along prominent coastal jet areas.
Moderate seas persist, especially offshore. More widespread fresh
to strong breezes build across the rest of the waters into Sunday
afternoon before subsiding into the beginning of next 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 until 3 AM PDT early this morning for Pt
     Arena to Pt Reyes 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.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...Murdock
MARINE...Murdock
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NWS MTR Office Area Forecast Discussion