Technical NOAA Weather Discussion

FXUS66 KMTR 100553
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
953 PM PST Mon Feb 9 2026

...New UPDATE, AVIATION...

.KEY MESSAGES...
Updated at 400 PM PST Mon Feb 9 2026

 - Widespread rain chances start Tuesday and linger through early
   Thursday, with a 75% chance of at least 1.50" in the Santa 
   Lucias

- General thunderstorm potential Tuesday afternoon through early
  Wednesday bringing chances for thunder, gusty winds, small 
  hail, and brief heavier rain

 - Strengthening south winds Tuesday into early Wednesday could
   produce gusts up to 40 mph in the high terrain of the Central Coast,
   peaking late Tuesday

- A break in rain chances Thursday into Friday, then rain chances
  return later Saturday into early next week

&&

.UPDATE...
Issued at 954 PM PST Mon Feb 9 2026

Plenty of high clouds today but still a pleasant day temperature
wise with most areas in the 60s while our Santa Rosa observer
reported a high of 70 this afternoon. IR satellite shows plenty of 
mid and high level clouds streaming over the region tonight which
will keep temperatures fairly mild overnight. Weak surface low
pressure is trying to develop just offshore in response to upper
level diffluence. No immediate impact for the Bay Area while 
rain and snow is starting to develop over the high Sierra as jet
energy passes over the region.

All eyes then focus on the deepening surface low, currently
measured at around 1005 mb located near 35N/131W. While not
particularly deep, after what seems like weeks of high pressure 
this system gives us some rain, wind and possible thunderstorms to
focus on over the next 2-3 days. Following the 00z guidance the 
surface low wont deepen too much more as it makes a beeline 
towards the Central Coast the next 24 hours. Latest trends have 
been to slow the timing of rainfall til late Tuesday 
afternoon/evening with some pre-frontal showers along the coast 
and especially the coastal hills from Santa Cruz mtns southward to
Big Sur.

Main impacts will likely be wind related on Tuesday with Gale 
Watches up for the coastal waters west of Big Sur. Southerly wind 
gusts in the 40 mph range dont look like they will penetrate too 
far inland but will have to at least consider some targeted wind 
advisories for the Monterey coast on Tuesday. 

Unfortunately the trajectory of the low will mean strong
southeasterly wind flow out of the Salinas Valley as well as the
Santa Clara valley. This is bad news for orographic lift with
easterly component worse than normal that will really enhance rain
shadowing for places like Livermore, San Jose and Salinas on
Tuesday. Despite the steep lapse rates we wont ever get ideal SW
or NW wind flow across the region which will keep rain totals in
check for many valley and interior locations. Final wildcard and
item to watch will be thunderstorm chances. As noted lapse rates
will be steep but little or no solar heating expected with 
blanket of cloud cover as a limiting factor. By Weds the low will 
weaken and wobble around with plenty of cold core showers that 
will drag down much cooler air from aloft. After weeks of spring 
like sunny and warm temps this system will bring a return of much 
cooler winterlike temps both during the day and the next few 
evenings. Showers to linger through Thursday morning then drying 
trend for much of Thursday midday to afternoon. 

High pressure to rebuild Friday and Saturday but a stronger and
colder system looks to bring more welcome rains to region Sunday
and followed by subsequent cold systems. 


&&

.SHORT TERM...
Issued at 1057 AM PST Mon Feb 9 2026
(This afternoon through Tuesday Night)

Mid to high level clouds are exist over much of the state today as 
the storm track under goes a shift. Near the surface a cold front 
existed the central coast of CA early this morning and ushered in 
cooler air, with 24 hour temperature trends generally around 2 to 8 
degrees cooler than yesterday. Light north winds behind the weak 
boundary have been able to succumb to local influences with terrain 
and coastal interactions, however a few higher elevation 
observations do show north to northeast winds with occasional gusts 
up to 15 to 20 mph (Santa Cruz Mts, Diablo Range, and some 
East/North Bay Mts).  

Current satellite places an upper trough and surface cyclone around 
600 miles off the coast of northern CA today. This upper trough will 
dig southeast and strengthen as the surface cyclone meets a 
stationary boundary located to the southeast. This places the 
location of these features around 300 miles off the coast of central 
CA tonight into Tuesday morning. The upper wave will become a closed 
low as these surface features phase and more moisture gets thrown in 
the mix. The upper closed low continues to deepen Tuesday as it 
rotates from positive to a more neutral tilt. This will also sling 
the deepening surface cyclone to the northeast as reaches ~1001 mb 
to 1005mb. Strong winds wrapping around these features will be 
reflected all the way down to the surface.. with a 925mb to 850mb 
jet of 35 to 45kts that moves over the central coast Tuesday 
afternoon into Tuesday night. The track doesn't quite align for 
stronger southeast winds down the Salinas Valley, and initial 
gradients from KSNS-KPRB remain around 1.6 to 2.2mb which points 
to lower confidence in winds trending stronger up the Salinas 
Valley as we get closer. The higher terrain is a different story 
with the stronger winds aloft. 12Z HREF probabilities 75% chances 
of at least 35 to 45 mph gusts in the higher terrain of the Santa 
Lucias and Diablo Range... with 25% chances for 45 to 55 mph. 
Winds will begin to strengthen midday Tuesday, but peak in these 
areas later Tuesday evening and night. 

A little after winds start to strengthen (Tuesday afternoon and 
evening) the upper closed low and surface cyclone will eventually 
land just right off the coast. Through the afternoon upper heights 
will trend down and increase mid-level lapse rates, as well as a 
quick window of isentropic ascent should move in with ample moisture 
(PWATs increasing to ~0.8"). Some lighter rain and clouds could be 
realized Tuesday afternoon as things approach. As lapse rates 
increase, instability will also increase. Rain will eventually 
become more widespread Tuesday evening with embedded showers and 
storms. Wind shear does exist, and will generally have more of a 
speed shear component.. however local terrain and coastal influences 
will very likely generate enhanced directional shear. Cooler air 
aloft, will help with ice forming and therefore lightning/small hail 
potential exists with some storms. Gusty winds and a few water 
spouts are not out of the question either. Locally heavier rainfall 
with storms will be seen too, however storms will be moving and the 
low will be wiggling around Tuesday night... leading to low 
confidence in training or stalling issues of storms. 

&&

.LONG TERM...
Issued at 1057 AM PST Mon Feb 9 2026
(Wednesday through next Sunday)

Wednesday morning, another piece of energy will rotate along the 
west side of the upper closed low... which will keep it centered 
over central CA through early Thursday. Although the features linger 
over the CWA, they will weaken starting Wednesday morning. Clouds 
and light to occasionally moderate rain at times will be seen 
Wednesday into early Thursday. Wind will gradually weaken Wednesday 
morning, with the stronger gusts likely remaining confident to the 
central coast (more details in short term section). 

As the upper troughing exits to the south, upper ridging will build 
in for later Thursday and into Friday. A break in rain chances will 
be seen, with more sunny skies and temperatures slightly warming.

Chances for a quick return to a wet pattern continue to increase. 
Starting Sunday, an upper trough will start to dig southward along 
the state returning beneficial rain and cooler temperatures. Weaker 
surface features look to accompany this system, resulting in higher 
confidence in light to moderate rain... beneficial rain. The upper 
trough continues to dig south and amplify into early next week, 
which should continue wet and cool conditions over the CWA. 

&&

.AVIATION...
(06Z TAFS)
Issued at 954 PM PST Mon Feb 9 2026

Mainly high clouds overnight through Tuesday morning. SE winds
beging to increase on Tuesday. -Shra possible late morning through
afternoon but steady rain likely hold off until after 00z. Thunder
chances in the region but not specically in the tafs.

Vicinity of SFO...VFR with light SE winds through 16z then 
increasing through the day Tuesday. A few showers possible Tuesday
afternoon with rain more likely after 00z.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Strong southeast winds for Salinas
increasing on Tuesday with gusts around 30kt. SE wind flow likely
to keep -shra to a minimum over the airports through Tuesay
afternoon.

&&

.MARINE...
(Today through Saturday)
Issued at 241 AM PST Mon Feb 9 2026

Fresh to strong northwest breezes prevail across the coastal
waters today. A low pressure system will then approach from the
west bringing rain to the coastal waters and bays Tuesday through
Wednesday. Southerly gale force gusts are possible on Tuesday in 
the waters south of the Golden Gate depending on the strength and 
track of the low. Rain chances return next weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 9 AM Tuesday to 3 AM PST Wednesday for 
     Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm.

     Gale Watch from 9 AM PST Tuesday through Wednesday morning for 
     Pt Pinos to Pt Piedras Blancas 0-10 nm.

     Small Craft Advisory until 3 AM PST Tuesday for Pt Arena to Pt 
     Reyes 10-60 NM.

     Small Craft Advisory from 9 PM Tuesday to 9 AM PST Wednesday for 
     Pt Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 3 PM Tuesday to 9 AM PST Wednesday for 
     Pigeon Pt to Pt Pinos 10-60 NM.

&&

$$

UPDATE.......RW
SHORT TERM...KR 
LONG TERM....KR 
AVIATION...RW 
MARINE...RW

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Prepared by Boulder-Creek.com Weather at: Mon Feb 9 22:30:02 PST 2026
From the National Weather Service