Bradley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

557
FXUS66 KMTR 121155
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
355 AM PST Thu Dec 12 2024

...New AVIATION, MARINE...

.SYNOPSIS...
Issued at 125 AM PST Thu Dec 12 2024

The first of multiple rounds of rain will impact the region
overnight with lingering showers into the rest of the day. More
impactful rainfall comes through Friday evening into Saturday with
gusty south winds throughout and minor flooding concerns in the
North Bay. Another round of generally light rain comes late Sunday
into Monday.

&&

.SHORT TERM...
(Today and tonight)
Issued at 125 AM PST Thu Dec 12 2024

Key Messages:
- First round of rain impacting the North Bay and Bay Area, moving
to the southeast through the night.
- Lingering showers through the day.
- More impactful rainfall comes through Friday evening into Saturday
with gusty south winds throughout and minor flooding concerns in the
North Bay.
- Another round of generally light rain comes late Sunday into
Monday.
- Coastal flooding concerns Thursday through Sunday due to a
combination of high surf and king tides.

As of 1 AM Thursday morning, the first of multiple bands of rainfall
has gone over the Bay Area and western Santa Cruz County, into the
North Bay, and was beginning to enter the city of San Jose. This
band is expected to continue moving towards the rest of the Bay Area
and Central Coast overnight. By the morning commute, the band should
be coming through the interior Central Coast with showers lingering
throughout the area through the rest of the day. The Bay Area and
the Monterey Bay region should expect around 0.5-1" of rain across
the valleys from the first system, with the coastal ranges seeing
localized totals up to 2" and the interior Central Coast (including
the Salinas Valley south of Salinas) topping out at 0.1-0.25". Gusty
northwest winds are expected through Thursday with gusts reaching 20-
30 mph along the coast, through gaps and passes, at the ridgelines,
and in northwest-southeast oriented valleys. High temperatures on
Thursday range from the middle to upper 50s in the lower elevations
to the middle to upper 40s across the higher elevations.

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 125 AM PST Thu Dec 12 2024

High resolution model guidance is hinting that a band of rain will
come through the region after midnight into Friday morning, with
generally light totals expected, up to 0.1" in the valleys to 0.1-
0.25" in the higher elevations. Afterwards, more significant and
impactful rain is expected to come through Friday into Saturday as
an upper level trough rapidly deepens in the Eastern Pacific and
supports two surface low pressure systems, one of which migrates up
into the Pacific Northwest and British Columbia, the other one
continuing east into California.

The greatest rain totals will be found across the North Bay, with 2-
3" of rain expected in the valleys and 3-5" of rain in the higher
elevations. Elsewhere, the coastal ranges see 1-2" of rain, the city
of San Francisco sees around 1.5-2", the East Bay, South Bay, and
the Monterey Bay region 0.5-1", and the interior Central Coast 0.25-
0.5", except in the farthest inland corners of Monterey and San
benito Counties where rain totals don`t exceed 0.2". The Weather
Prediction Center has issued a Marginal Risk for Excessive Rainfall
(at least 5% probability of rainfall exceeding flash flood guidance)
for northern and Central Sonoma County on Friday, including the
Santa Rosa-Rohnert Park area, the coastal ranges, and the Mayacamas.
On Saturday, that Marginal Risk expands to cover the rest of the
North Bay, edging into the northern tip of the San Mateo Peninsula
(including the city of San Francisco) and the Richmond-Berkeley
area. Minor urban and small stream flooding is possible in the North
Bay, including the typical trouble spots along Laguna de Santa Rosa
and Mark West Creek.

In addition, as the low develops off the coast, a band of breezy and
gusty winds will develop and are expected to impact the North Bay
before moving southward, with gusts up to 40-50 mph along the coast,
at the higher elevations, and through gaps and passes. This is
further supported by the Ensemble Forecast Index, which shows
index values of 0.7-0.8 and a shift of tails above 0, both
indicators supporting a potential significant wind event. High
Wind Watches have been issued for the North Bay coast from 7 PM
Friday to 7 AM Saturday, and for the San Mateo Peninsula coast,
the coastal regions of Santa Cruz and Monterey Counties, and the
Santa Cruz and Santa Lucia ranges from 4 AM to 4 PM Saturday.
Secure loose objects outdoors and monitor updated forecast
information, particularly as further wind products may need to be
issued.

Finally, the incoming low pressure system will support a low chance
(around 10% probability) of convection, with the ECMWF showing CAPE
values up to 200 to 300 J/kg through Saturday, mainly in the coastal
regions. K-Index values topping out at 30-32 support a possibility
of scattered thunderstorms, with the area of greatest risk coming
into the North Bay early Saturday morning and moving towards the
Central Coast by the late morning and early afternoon hours.

There`s a break in the rain on Sunday before another disturbance
comes through on Monday into the early part of Tuesday. At the
moment, it appears that this system will be less intense than the
one before it, with 0.5"-1" of rain in the North Bay (locally up to
2" in the higher elevations), and lesser amounts in the interior
East Bay, South Bay, and Central Coast. Once that system moves out,
the ensemble models show upper level ridging taking hold for a
couple of days, before rain chances return to the region towards the
end of next week.

&&

.AVIATION...
(12Z TAFS)
Issued at 341 AM PST Thu Dec 12 2024

Surface analysis and radar both indicated the surface cold front
is pushing through the Bay Area this morning. The fropa will bring
a wind shift and an abrupt end from steady rain to showers/vcsh.
Cigs will also lift with the behind the front to generally VFR for
a few hours. Another batch of steady rain will arrive this
afternoon followed by a transition back to showers/vcsh late this
evening and overnight. Simply put, a dynamic forecast over the
next 24 hours. One more notable change from previous tafs was to
lower wind speeds. While the fropa will bring an uptick in winds,
not seeing the stronger gusts.

Vicinity of SFO...SFO already saw the wind shift and will be
going -shra to vcsh rather quickly (by 13Z). Elevated cigs around
3-4k ft there afternoon. Left gusts up to 25 kt this afternoon,
but conf is pretty low (20-30%)

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Wet this morning with MVFR to VFR
conditions. Precip will transition to showers/vcsh around 17-19Z.
Breezy SE flow will linger for KSNS through 18-20Z.

&&

.MARINE...
(Today through Tuesday)
Issued at 341 AM PST Thu Dec 12 2024

Rain will end north to south today as a cold front exits the
region. Breezy winds with the frontal passage and higher wave
heights will keep hazardous conditions for smaller craft today. A
stronger storm system will impact the coastal waters this weekend
bringing another round of higher waves and much stronger winds.
Occasional storm force gusts up to 50 kt will be possible
Saturday afternoon. Dry weather returns for Sunday then another
low brings rain to the coastal waters and bays Monday.

&&

.BEACHES...
Issued at 350 AM PST Thu Dec 12 2024

Previous forecast generally still on track. Still expecting a
larger swell well offshore currently to enter the northern waters
this afternoon. People should use caution if they venture to the
beaches/coastline/bay shoreline through the upcoming weekend.

Previous details: There will be multiple hazards across the Bays,
Pacific Ocean, and their associated beaches as three storm
systems take aim at the West Coast and King Tides return. A
Coastal Flood Advisory has been issued from 6 AM Thursday through
1 PM Monday along the bayshore of the San Francisco Bay and San
Pablo Bay with the highest tides: 6.74 ft at 8:12 am Thursday,
6.98 ft at 8:54 am Friday, 7.07 ft at 9:37 am Saturday, 7.02 ft at
10:22 am Sunday, and 6.82 ft at 11:08 am Monday. These very high
tides in tandem with long period northwesterly swell will allow
for large sets of waves to run a lot farther up the beaches. A
High Surf Advisory has been issued for 1 PM Thursday through 4 AM
Friday for all west and northwest facing beaches for breaking
waves of 18-22 feet. Other impacts will be rip current risk,
longshore current risk, gale-force gusts, slight thunderstorm
chances, and widespread rainfall. There are going to be poor
conditions everywhere, especially on the water or at the beach.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory until 1 PM PST Monday for CAZ006-506-508.

     High Surf Advisory from 1 PM this afternoon to 4 AM PST Friday
     for CAZ006-505-509-530.

     High Wind Watch from late Friday night through Saturday
     afternoon for CAZ006-509-512-517-529-530.

     High Wind Watch from Friday evening through Saturday morning for
     CAZ505.

PZ...Small Craft Advisory until 3 AM PST Friday for Mry Bay.

     Small Craft Advisory until 9 AM PST Friday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Gale Warning from 9 AM to 9 PM PST Friday for Pt Arena to Pt
     Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory until 9 PM PST Friday for Pt Reyes to
     Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 PM PST Friday for Pigeon Pt to Pt
     Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...MM
MARINE...MM

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