Hercules, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

745
FXUS66 KMTR 101207
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
507 AM PDT Thu Apr 10 2025

...New AVIATION...

.SYNOPSIS...
Issued at 320 AM PDT Thu Apr 10 2025

Warm temperatures and light winds will continue today with minor
HeatRisk concerns. Pleasant weather will continue through the
weekend into the beginning of next week.

&&

.SHORT TERM...
(Today and tonight)
Issued at 320 AM PDT Thu Apr 10 2025

A progressive longwave pattern, with our area situated on the
backside of a flattening upper level ridge, will continue to steer
more impactful troughing to our north. A weak shallow marine layer
can be seen along the coastline extending from the Norcal south to to
Santa Cruz. The shallow marine layer will struggle to advance
farther inland through the remainder of this morning before mixing
out later today. A trough axis well to our north will move inland
this afternoon and push a weak and dry cold front south into our
area tonight. The cooler and more importantly, drier airmass will
help limit widespread stratus development late tonight into early
Friday morning.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 320 AM PDT Thu Apr 10 2025

The progressive synoptic pattern will leave our area in between more
potent energy moving inland to our north across the Pacific Northwest
and a cut off low spinning off the coast of SoCal to our south. The
weak forcing across the Bay Area and Central Coast will make
forecasting the impacts of the potential marine layer development
the next few days a little more difficult, but otherwise expect very
pleasant spring weather through the extended forecast. The cooler
and drier airmass in place tomorrow and Saturday will result in some
cooler than normal temperatures to start the day, before quickly
improving by midday. The cutoff low begins to split from the
synoptic flow late Saturday, and then begins to retrograde off the
SoCal coast by Sunday. Overall this will result in weak but
steady offshore flow Sunday and Monday lifting temperatures back
up to around 5 degrees above normal and the return of more
widespread minor HeatRisk concerns to begin next week. The
extended forecast remains dry with the exception of some spotty
coastal drizzle at times. Long term deterministic guidance
suggests it will be over 10 days until our next chance at
meaningful rainfall.

&&

.AVIATION...
(12Z TAFS)
Issued at 507 AM PDT Thu Apr 10 2025

Coastal stratus and fog /IFR-LIFR/ continue to develop and move
southeastward along the coastline under a compressed marine layer.
Local intrusions of stratus and fog are taking place through the
Golden Gate and into the North Bay. Dense fog with a visibility
less than 1/4 mile has reached Petaluma Municipal Airport and a
light southerly wind is advecting fog to Sonoma County Airport
where the visibility and ceiling are recently lowering to IFR. A
thermal trough in lower levels of the atmosphere over the coastal
waters will move eastward over the top of the marine layer this
morning which may help keep or slightly deepen the marine layer
this morning. Stratus and fog will mix out later in the morning
under diurnal surface warming and vertical mixing. HREF output
show stratus and fog /IFR/ returning tonight and Friday morning.

Vicinity of SFO...VFR except low to moderate confidence tempo IFR
ceiling 13z-16z this morning as a lower level thermal trough moves
over the top of the marine layer stratus and fog. A west wind will
continue through morning (and afternoon) increasing the chance
that a stratus ceiling moves in from the west for a few hours this
morning. The same lower level thermal trough should in combination
with diurnal surface warming later in the morning help to mix out
the stratus for a VFR forecast continuing through the afternoon.
West wind in the afternoon becoming gusty to 20 to 25 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...IFR-LIFR forming due to stratus and fog
across the Monterey Bay and along the Monterey Bay shoreline. An
eddy circulation will likely spin up across the inner Monterey
Bay during the morning per model wind and humidity forecasts, the
stratus signature on satellite suggests it may already be forming.
From later morning through afternoon diurnal surface warming and
vertical mixing will help mix out the stratus and fog with a
night-time return of stratus and fog /IFR/ likely.

&&

.MARINE...
(Today through Tuesday)
Issued at 320 AM PDT Thu Apr 10 2025

Northwest winds becoming gusty through late week and weekend. A
coastal jet will result in locally stronger winds for areas south
of Point Sur causing hazardous conditions for small craft into
the end of the week. A larger swell will build over the weekend
and early next week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM to 3 PM PDT Friday for Pigeon Pt
     to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena
     to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Reyes
     to Pigeon Pt 0-10 nm.

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

&&

$$

SHORT TERM...JM
LONG TERM....JM
AVIATION...Canepa
MARINE...Canepa

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