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NWS Technical
Weather Discussion |
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FXUS66 KMTR 150511
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
911 PM PST Sat Feb 14 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 556 PM PST Sat Feb 14 2026
- Widespread rain arrives tonight and continues through much of
next week as a series of three storm systems arrive
- Strong winds arrive Sunday and continue through mid-week; Wind
Advisory likely for the Central Coast Monday into Tuesday
- A Coastal Flood Advisory is in effect through Tuesday for minor
high tide flooding
- Much colder with mountain snow mid to late week
&&
.UPDATE...
Issued at 556 PM PST Sat Feb 14 2026
The 00Z surface analysis shows a 1006 mb low pressure system off
the coast of Northern California with a long cold front extending
to the SW. The system is just now moving +n of the jet stream (to
the left of the jet core when looking top down). This means the
system is transitioning to a mature cyclone and will slow down,
stop deepening, and eventually occlude as the surface cold front
catches and undercuts the warm front. While the cyclone itself is
now fairly stationary, the associated cold front will progress
towards the coast through the night, bringing organized prefrontal
rain to the Bay Area as early as dawn Sunday, with a later onset
further south. The slow moving nature of this system will prolong
the rain well into Monday with FROPA expected sometime during the
day Monday. As the front moves through, expect the rain intensity
to increase briefly thanks to the increased lift of the wedge of
cold air. Behind the front the steady rain will transition to more
spotty convective showers that continue into Tuesday. The winds
will also shift from southerly to NW allowing the temperatures to
drop sharply after the front moves through.
-DJF
&&
.SHORT TERM...
Issued at 149 PM PST Sat Feb 14 2026
(This evening through Sunday)
Mostly clouds this afternoon, but there have been a few glimpses
of sunshine. The sunshine is a welcomed sight this afternoon
because we may not be seeing much of it over the next five days.
As mentioned earlier this morning, the next round of rain will
arrive late this evening and early tonight. Afternoon surface
analysis shows a weak surface low west of Cape Mendocino. If we
zoom out a little bit more and move to the upper atmosphere we'd
see a highly amplified jet pushing through the Aleutians and
digging off the West Coast behind the surface low. Over the next
12-24 hours this upper level jet will dig further resulting in
cyclogenesis of the weak surface low. Additionally, it's not
uncommon for these digging jets and deepening lows to slow their
W to E progress. This is the case with this low as per the latest
guidance. The weak surface low will slowly work its way eastward
gradually spreading precip over the North Bay initially( Saturday
PM) before moving S and E Sunday. By sunrise Sunday most of the
Bay Area and Central Coast will be experiencing some precip.
Speaking of precip, expect intensity of precip to increase with
coverage during the day Sunday. Highest intensity will occur over
orographically favored regions: N Bay Mts, Santa Cruz Mts, Santa
Lucia Mts. Unlike our good AR setups, this system will not have a
huge tap straight to HI. The highly amplified longwave pattern has
limited this feature. In fact, when the tap finally does link up
with the low pressure it will be well into SoCal and Baja. That
being said, still expecting some period of moderate to locally
heavy rain late Sunday afternoon through Sunday night. To account
for the periods of higher intensity WPC Excessive Rainfall Outlook
through Monday morning does have the Bay Area and Central Coast
in a Marginal(5%) mention for flash flooding. One final wrinkle
precip wise will be the chance for thunderstorms. As the low
deepens over the coastal waters and gets a boost from the upper
jet a 10-20% chance for thunderstorms exists over the waters and
near the coast. SPC Day 2 Outlook has the waters and coastal
region in a general mention for thunderstorms.
Another weather impact to finish the weekend will be the winds. As
the low deepens and surface pressure gradients tighten southerly
winds will ramp up. Southerly flow increase Saturday night and
peaks Sunday afternoon thanks to coastal terrain enhanced jets.
Gusts of 15-30 mph will be common with locally higher gusts of up
to 45 mph near the coastline and coastal peaks.
&&
.LONG TERM...
Issued at 249 PM PST Sat Feb 14 2026
(Sunday night through next Friday)
The weekend storm's influence will linger into the beginning of
the next work week as it slides down the coast. The AM commute on
Monday will be a mess with lingering moderate to locally heavy
rainfall, gusty winds, and even a chance (10-20%) chance for
thunderstorms. The dynamic forcing on Monday gets a little more
spicy thanks to a solid low level jet interacting with a robust
mid and upper level jet leading to enhanced shear. Given the
threat for convection any cells that develop cloud be of the
rotating variety, especially over the Central Coast coastal
waters and Central Coast. ECMWF EFI highlights higher values of
CAPE shear over this region as well. CAPE shear is a combo of CAPE
and bulk shear, which sometimes can show areas of stronger
convection. SPC Outlook put this region in a Marginal risk for
severe storms.
Monday afternoon and Monday night will be a transition period as
one system exits southward and system quick on its heels moves in
from the N. Round two will have some similarities to the weekend
low: periods of moderate to heavy rain, chance for thunderstorms,
and gusty winds. However, the bigger difference will be the
temperatures associated with this system. It'll be much colder
and will bring the first notable snow for 2026 around the Bay Area
and Central Coast. Rainfall amounts Monday night through
Wednesday: 1-1.5" most areas and up to 2-3" Santa Cruz Mountains
and Santa Lucia Range. No real change from previous thinking for
winds: increasing winds initially over the waters and then land
with strongest winds aligned valleys, coast, and higher peaks.
This enhanced gradients with cold advection will lead to stronger
winds overall. As of now not thinking High Wind Warning, but more
in the way of Wind Advisory Monday night through Tuesday. Will
fine tune this on future forecasts. Winds will finally ease
Wednesday into Thursday.
Let's talk temps and snow. Cold advection really kicks in Monday
evening into Monday night from N to S. Snow levels initially in
the 4k range then drop 2-3k by Tuesday night/Wednesday. That means
precip will eventually see a switch over to snow over the higher
peaks. When it comes to snowfall totals: highest amounts will be
over the Santa Lucia range and Gabilan range. The potential
wildcard will be the potential convective enhancement. This could
lead to higher amounts and lower snow levels. Don't have Santa
Cruz in the mix at the moment, but wet bulb zero and snow levels
could be pushed lower with convection. Regardless, a few inches
seems plausible over the high peaks with the highest peaks above
Big Sur approaching a foot. If things line up right 10-20" is not
out of the question for the Santa Lucias. Will likely need a
Winter Wx Advisory for this area Tuesday/Wednesday. As the snow
levels drop that will also push overnight lows colder Tuesday
night. Given the damp conditions and cold temperatures in the 30s
and 40s we may need a mix of Cold Wx Adv and Extreme Cold
Warnings.
While precip through midweek looks to be heavy at times the main
stem rivers can handle it right now. We've been dry for a while.
The more likely scenario will be minor flooding with urban and
small stream flooding.
Finally, one more system arrives late in the week and next
weekend with more rain and high level snow.
&&
.AVIATION...
(06Z TAFS)
Issued at 911 PM PST Sat Feb 14 2026
MVFR to low-end VFR conditions prevail across the region with
numerous mid- to high level clouds across the Bay Area and Central
Coast associated with an approaching low pressure system. Showers
are starting to move into the North Bay and the San Mateo Peninsula
and will continue expanding into the rest of the region through the
night. Transitory IFR conditions are possible with some of the
stronger showers that develop. More consistent rainfall is expected
Sunday afternoon and evening, with the main rain band progressing
through the region. Gentle to breezy south flows continue through
the night, becoming stronger Sunday morning and afternoon in advance
of a front. Timing of the strongest frontal impacts is rather
uncertain; the high resolution model output has not captured the
evolution of the system very well and the progression varies from
model to model. The TAFs reflect a best guess forecast but will need
to keep a close eye on observations overnight.
Vicinity of SFO... Generally MVFR-low end VFR conditions at the
terminal. Gentle south winds continue through the morning, ramping
up to a strong breeze on Sunday with gusts topping out in the 25-30
kt range in the afternoon and evening, before the gusts abate later
in the day although sustained winds remain breezy. Showers are
expected to approach the terminal early Sunday morning followed by
light to moderate rain developing through the day into the evening
hours. The main rain band may start to move out of the terminal
close to the end of the TAF period, but this is a low confidence
forecast at this time.
SFO Bridge Approach... Similar to SFO.
Monterey Bay Terminals... MVFR to low end VFR across the region and
through the TAF period. Light to gentle southerly winds expected
through Sunday morning, when the winds will increase in advance of a
frontal system with the gusts increasing to around 25-30 kt in the
afternoon. Pre-frontal showers are expected to arrive Sunday morning
and afternoon. Latest high-resolution model guidance suggests that
more steady rainfall arrives sometime late Sunday afternoon
into the evening, but timing is still a little uncertain.
&&
.MARINE...
(Tonight through next Friday)
Issued at 911 PM PST Sat Feb 14 2026
A series of storm systems moves through the region starting
tonight and lasting through much of the upcoming week. By Sunday
expect periods of light to moderate rain while a fresh to strong
southerly breeze generates rough seas. Southerly winds strengthen
to strong with near gale fore wind gusts on Sunday and are likely
through midweek as a high westerly swell arrives. Thunderstorm
chances increase behind the initial front and linger through
Tuesday.
&&
.BEACHES...
Issued at 556 PM PST Sat Feb 14 2026
The combination of spring tides and storm surge will bring minor
high tide flooding to the San Francisco Bay and Monterey Bay
through Tuesday. Up to 1.0 ft of inundation is expected in the
San Francisco Bay, with up to 1.5 ft in the Monterey Bay. At the
San Francisco tidal gauge, high tide is expected to at 9:34 AM
Sunday, 10:16 AM Monday, and 10:58 AM Tuesday. High tide timing
varies up to 90 minutes earlier or later along the Pacific Coast
and throughout the San Francisco Bay, respectively.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Coastal Flood Advisory from 7 AM Sunday to 3 PM PST Tuesday for
CAZ006-506-508.
Coastal Flood Advisory from 4 AM Sunday to 3 PM PST Tuesday for
CAZ529-530.
PZ...Small Craft Advisory from 9 AM to 3 PM PST Sunday for SF Bay N
of Bay Bridge.
Small Craft Advisory until 3 PM PST Sunday for Mry Bay.
Small Craft Advisory until 3 AM PST Monday 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 until 3 AM PST Sunday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
Gale Warning from 3 AM to 3 PM PST Sunday for Pt Pinos to Pt
Piedras Blancas 0-10 nm.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...DialH
MARINE...DialH
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Prepared by Boulder-Creek.com Weather at: Sat Feb 14 22:30:03 PST 2026
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Revised:
29 Mar 2008 09:53 -0800 GMT
(Pacific) |
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