Jenner, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

456
FXUS66 KMTR 280008
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
508 PM PDT Tue May 27 2025

...New AVIATION...

.SYNOPSIS...
Issued at 1249 PM PDT Tue May 27 2025

Near normal temperatures are anticipated through mid-week with
impactful heat by Friday. The fire weather threat will elevate
through the end of the week. Thereafter, temperatures are expected
to return to near normal values.

&&

.SHORT TERM...
Issued at 2 PM PDT Tue May 27 2025
(This evening through Wednesday)

Short Term Key Messages
*Minor Coastal Flooding due to Spring Tides
*Morning Coastal Drizzle
*Seasonable Temperatures

Very minor coastal flooding is anticipated late tonight into the
pre-dawn hours on Wednesday due to Spring Tides. At this time,
impacts are anticipated to be confined to areas along the
immediate San Francisco Bay shoreline. Note, due to a technicality
with this product, graphics depicting to Coastal Flood Advisory
are likely an overestimate of areas impacted/potential inundation.

Modest onshore flow is anticipated to continue on Wednesday
morning as the SFO-SAC gradient holds steady around 1.5mb this
afternoon and into tomorrow. This gradient is down by about 1mb
compared to last 24 hours and as a result, it`s probable that the
marine layer will compress and its reach inland will be
less in the coming days. This corroborates with the 2km PGE/SJSU
WRF cross-sections which indicate a marine layer depth (using the
90% isohume) around 1200-1500 ft AGL. Forecast soundings
in tandem with HREF output yields high confidence in morning
stratus infiltrating valleys across the Bay Area and Central
Coast. Where ascent is sufficient, there`s a reasonable
opportunity for morning drizzle and patchy fog that may result in
reduced visibility for the Wednesday morning commute. At this
time, probabilities of visibility dipping down below 1 mile are
under 15% (with values maximized across Pacific coastal areas).

With the marine stratus dissipating a little earlier in the
morning on Wednesday, we`ll have the potential to get a little
warmer. Still, sufficient humidity should keep temperatures near
seasonal values on Wednesday.

&&

.LONG TERM...
Issued at 2 PM PDT Tue May 27 2025
(Wednesday night through next Monday)

Long Term Key Messages
*Well above normal temperatures
*Impactful heat

Outside of the Pacific coast regions, the influence of the marine
layer will diminish as we progress through the end of the work
week. In fact, cross sections indicate that the depth of the
marine layer will be around or just under 1000 ft AGL. This may offer a
brief period of reduced visibilities along the coast on Thursday morning.
As the pressure gradient between the coast and interior sections weakens,
the onshore component to the wind field will diminish and our
warming trend will ensue. By Thursday afternoon, most areas will be 2-5
degrees above normal (except along the coast) with HeatRisk values
creeping up into the `Minor` category. This heat is largely
hazardous to those that are extremely sensitive to warmer
conditions.

Friday appears to be the warmest day in the 7 to 10 day outlook
period. The mid-level ridge axis will orient itself from SW to NE
across the Bay Area and Central Coast late Thursday and into the
day on Friday. As this occurs, an upper level low, currently
pegged near 30N 135W will be nudged southward, creating a brief
Rex Block across the western CONUS. The synoptic wind field will
be such that it discourages onshore flow and may even induce a
little bit of light (5-15 mph) offshore flow. This in tandem with
a largely subsident airmass, albeit for 24-36 hours, results in
widespread `Moderate` to isolated pockets of `Major` HeatRisk.
This type of heat is a little higher end and has the potential to
impact more of the general population. After internal and intra-
office collaboration, we`ve elected to to issue a broad Heat
Advisory that encompasses a good chunk of the interior regions of
the North Bay, East Bay and Central Coast for Friday from 11am
through 8pm. Currently, the product does not include some of the
Santa Cruz Mountains (e.g., Boulder Creek and Ben Lomond), but
we`ll take a closer look as we proceed through the week for any
tweaks in space. Regardless, max temperatures in areas near and
within our Heat Advisory are advertised to range between the mid
90s to near 105 degrees with parts of the East Bay interior and
southern Salinas Valley being the "hot spots" for Friday.

Be sure to abide by heat safety protocols such as drinking plenty
of water/electrolytes, take breaks in the shade or air-condtioning
(where applicable), and also NEVER leave children or pet in
unattended vehicles. Additionally, if heading to the beach for
relief from the heat, be mindful of the marine hazards. Cold
weather shock will be the main hazard (so be cognizant of your
time in the water).

Saturday should see a cool down, though interior regions may
still approach Heat Advisory caliber HeatRisk values and
extensions in time of the current product may be needed. As the
upper low slides southward, meager onshore flow (largely driven by
the pressure differences between the Central Valley and Coastal
Regions) should ensue and be sufficient to bring temperatures back
down to near normal conditions. This is dependent on the upper
low sliding southward, however. If the upper low lingers or even
drifts farther north, sensible weather may be a little different
than currently advertised. One such scenario that`s on the table
is that more widespread impactful heat lingers across a larger
geographic region on Saturday (due to continued modest offshore
flow). Furthermore, some medium/long range NWP that offers a more
northern track to the upper low indicates that this feature could
pull in sufficient 700-500mb moisture that could support some
high-based convection. Some of the ensemble model groupings do
paint a few hundredths of an inch across the state during the
latter half of this weekend and into the first full week of June.
For now, we`ll roll with the deterministic NBM that offers little
to no precip, but we`ll continue to monitor this potential.
Climatologically, June is the month in which we see the greatest
number of days with at least 10 lightning flashes, particularly
across the higher terrain of southern San Benito/Monterey
counties.

&&

.AVIATION...
(00Z TAFS)
Issued at 447 PM PDT Tue May 27 2025

Onshore flow has begun to increase near Monterey Bay with ceilings
expected to go from MVFR to IFR by sunset, and LIFR possible by
early Wednesday morning. Expect MVFR/IFR ceilings to set in across
the Bay Area after midnight, persisting until early afternoon
Wednesday. With the more robust marine layer in place, all
terminals are expected to be impacted with low stratus ceilings by
daybreak Wednesday, and begin to mix out by Wednesday afternoon.
Periods of drizzle and fog may lower visibility during the
overnight for the Bay Area terminals.

Vicinity of SFO...Onset of MVFR/IFR ceilings is not expected until late
this evening, and will persist into the early afternoon on
Wednesday, when VFR conditions will return for the remainder of
the TAF period. Patchy fog and drizzle may lower visibility at
times during the overnight hours into early Wednesday morning.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Onshore winds have increased with MVFR
ceilings in place, expected to become LIFR during the overnight
hours into Wednesday morning. Periods of VFR are expected by
Wednesday afternoon, however the marine layer is expected to
return with MVFR ceilings by early evening Wednesday.

&&

.MARINE...
(Today through Sunday)
Issued at 1029 AM PDT Tue May 27 2025

Northwest winds will mainly ease over the coastal waters through
Tuesday night. Northwest winds will increase again Wednesday with
gale force gusts developing over the southern inner coastal
waters later Wednesday. Stronger winds during the midweek will
lead to hazardous conditions for small craft due to steep wind
waves.

&&

.FIRE WEATHER...
Issued at 2 PM PDT Tue May 27 2025

The expected warm up for the second half of the week will
translate to an elevated fire weather threat. This is due to the
increased drying of fine fuels (1 and 10 hour fuels) and even
some of the smaller timber fuel types. Wednesday and into the
first portion of the weekend is when afternoon RH in some spots
will dip down to near 15%. While overnight humidity recovery will
largely rebound above 60%, the higher terrain of the North Bay
Mountains, as well as the Santa Lucia, Diablo, and Gabilan Ranges
may not see max RH above 50%. Fortunately, wind gusts are
anticipated to remain largely below critical thresholds that would
warrant a Fire Weather Watch/Red Flag Warning. Still, individuals
across the area should be mindful of handling open flames, secure
tow chains, and avoid activities that could spark a grass fire.
This is particularly true given the slight uptick in vegetation
fires over the past couple of weeks.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 10 PM this evening to 2 AM PDT
     Wednesday for CAZ006-506-508.

     Heat Advisory from 11 AM to 8 PM PDT Friday for CAZ504-506-510-
     513>518-528.

PZ...Small Craft Advisory until 9 PM PDT this evening for SF Bay N of
     Bay Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Wednesday for Mry Bay-
     SF Bay N of Bay Bridge.

     Small Craft Advisory from 9 AM Wednesday to 3 AM PDT Thursday
     for Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60
     NM.

     Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Thursday
     for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-
     60 NM-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory from 9 AM to 3 PM PDT Wednesday for Pt
     Pinos to Pt Piedras Blancas 0-10 nm.

     Gale Warning from 3 PM Wednesday to 3 AM PDT Thursday for Pt
     Pinos to Pt Piedras Blancas 0-10 nm.

&&

$$

SHORT TERM...Bain
LONG TERM....Bain
AVIATION...JM
MARINE...RGass

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