Geyserville, California Weather Forecast Discussion

572
FXUS66 KMTR 061808
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1108 AM PDT Mon Oct 6 2025
...New AVIATION...
.KEY MESSAGES...
Updated at 418 AM PDT Mon Oct 6 2025
- Warmer and drier conditions through midweek, with moderate
   offshore wind expected today and Tuesday in the higher
   elevations
- Unsettled weather returns late this week
&&
.UPDATE...
Issued at 853 AM PDT Mon Oct 6 2025
Clear sky conditions across much of the region this morning with
offshore flow aloft. The exception is around Half Moon Bay and down
along the Big Sur Coast as a very shallow marine layer remains less
than 500 feet in depth. As a result of the offshore winds,
temperatures will warm-up quickly this morning and into the
afternoon. Maximum temperatures this (Monday) afternoon will warm
into the low to mid 70s along the immediate coastline with low to
upper 80s across inland areas. Downtown San Francisco has around a
12% probability of exceeding 85 degrees F with southeast portions of
the city at around 25%. Places such as Novato, San Rafael, San
Mateo, Redwood City, and Gilroy have a 30-50% chance of exceeding 90
degrees F. These temperatures are generally around 5-10 degrees
above seasonal averages across the North Bay and Bay Area. It is
going to be downright warm this afternoon (and again tomorrow).
RGass
&&
.SHORT TERM...
Issued at 418 AM PDT Mon Oct 6 2025
(Today and tonight)
A relatively weak offshore upper level low will slowly retrograde
during the day today while maintaining a fetch of weak offshore
flow that will tame the marine layer from making progress inland.
Low stratus should remain offshore and be patchy (if present at
all) throughout the day from Monterey Bay down the Big Sur
coastline. With offshore flow today we`ll see warmer than normal
temperatures, with coastal communities feeling the biggest
difference without much help from the marine layer. Overnight lows
into Tuesday will be 5-10 degrees above normal with some elevated
locations in the thermal belts 15+ degrees above normal along
with poor RH recovery.
&&
.LONG TERM...
Issued at 418 AM PDT Mon Oct 6 2025
(Tuesday through Sunday)
Offshore flow will continue to influence max temps on Tuesday,
with lesser certainty near the coast given weak mixed/to
occasionally offshore flow late Tuesday morning into Tuesday
evening. By Wednesday a weak offshore surface trough located
somewhere between the Bay Area and the Big Sur coastline will
further complicate low- layer vertical wind profiles, however
temperatures overall across the the region will be cooler as the
upper level disturbance begins to evolve into an open wave, move
onshore and merge with a deepening trough to the north. The
relatively weak/mixed low level flow along the coast should begin
to become more steadily onshore by late Thursday into Friday. Rain
chance increase Friday into the weekend, however there is still a
lack of consensus in the overall synoptic pattern, along with the
presence of a tropical system in the SE Pacific to further
confuse the NWP models.
&&
.AVIATION...
(18Z TAFS)
Issued at 1107 AM PDT Mon Oct 6 2025
VFR at all terminals today with light offshore winds this morning
becoming light onshore this afternoon. Offshore winds will return
again tonight allowing for most terminals to remain VFR through
the night. The exception will be immediate coastal terminals where
low level moisture will return tonight and may bring in very low
clouds under the light offshore flow. This should be confined to
the Pacific coast terminals such as MRY and HAF.
Vicinity of SFO...VFR. Light offshore winds, just above the
surface, will maintain VFR for most of the day. Afternoon surface
winds should become NW, but not very strong. This will help to cap
the temperature rise. Tonight winds will go calm and some low
level moisture will attempt to work its way around the corner at
the golden gate, but should be thwarted by the dry air locked up
inland and over the immediately adjacent bay. If there was going
to be a caveat to this forecast, it would be to say something
about a very low probability of some ground fog (BCFG) or very
low clouds (few002) creeping around late in the nighttime hours or
about sunrise. The odds of this happening are so low though, it
did not make the official forecast. Tuesday will bring another VFR
warm day.
SFO Bridge Approach...Similar to SFO. VFR will dominate.
Monterey Bay Terminals...VFR. Overnight there is a good shot at
some low level humidity making it to the area, coming up from the
south. This low level humidity will bring some low clouds and
visibility reductions. How this plays out, low clouds versus low
visibility, will depend on how shallow the marine layer actually
stays. Either way, we`re looking at IFR or LIFR for a few hours in
the AM before it breaks out again.
&&
.MARINE...
(Today through Saturday)
Issued at 853 AM PDT Mon Oct 6 2025
Light to moderate winds accompanied by low to moderate seas will
prevail through Tuesday. An approaching system will begin to
increase winds and seas mid to late week.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&
$$
SHORT TERM...JM
LONG TERM....JM
AVIATION...BFG
MARINE...BFG
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NWS MTR Office Area Forecast Discussion