Wind Advisory 18, NWS San Francisco Bay Area, CA

262 
WWUS76 KMTR 271605
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
905 AM PDT Fri Oct 27 2023

CAZ506-280200-
/O.CON.KMTR.FR.Y.0017.231028T0800Z-231028T1700Z/
North Bay Interior Valleys-
905 AM PDT Fri Oct 27 2023

...FROST ADVISORY REMAINS IN EFFECT FROM 1 AM TO 10 AM PDT
SATURDAY...

* WHAT...Temperatures of 36 or lower will result in frost 
  formation.

* WHERE...North Bay Interior Valleys.

* WHEN...From 1 AM to 10 AM PDT Saturday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

CAZ502-504-512-514-515-280200-
/O.CON.KMTR.WI.Y.0018.231028T1500Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
905 AM PDT Fri Oct 27 2023

...WIND ADVISORY REMAINS IN EFFECT FROM 8 AM SATURDAY TO 5 PM PDT
SUNDAY...

* WHAT...North to northeast winds of 20 to 30 mph with gusts up 
  to 45 mph expected. Ridgetop gusts over 50 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...From 8 AM Saturday to 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

* ADDITIONAL DETAILS...Enhanced fire weather conditions are 
  expected in these areas and a Fire Weather Watch is also in 
  effect.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

839 
WWUS76 KMTR 280110
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
610 PM PDT Fri Oct 27 2023

CAZ506-280800-
/O.CON.KMTR.FR.Y.0017.231028T0800Z-231028T1700Z/
North Bay Interior Valleys-
610 PM PDT Fri Oct 27 2023

...FROST ADVISORY REMAINS IN EFFECT FROM 1 AM TO 10 AM PDT
SATURDAY...

* WHAT...Temperatures of 36 or lower will result in frost 
  formation.

* WHERE...North Bay Interior Valleys.

* WHEN...From 1 AM to 10 AM PDT Saturday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

CAZ502-504-512-514-515-280800-
/O.CON.KMTR.WI.Y.0018.231028T1500Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
610 PM PDT Fri Oct 27 2023

...WIND ADVISORY REMAINS IN EFFECT FROM 8 AM SATURDAY TO 5 PM PDT
SUNDAY...

* WHAT...North to northeast winds of 20 to 30 mph with gusts up 
  to 45 mph expected. Ridgetop gusts over 50 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...From 8 AM Saturday to 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

* ADDITIONAL DETAILS...Enhanced fire weather conditions are 
  expected in these areas and a Fire Weather Watch is also in 
  effect.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

289 
WWUS76 KMTR 280741
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
1241 AM PDT Sat Oct 28 2023

CAZ506-281545-
/O.CON.KMTR.FR.Y.0017.231028T0800Z-231028T1700Z/
North Bay Interior Valleys-
1241 AM PDT Sat Oct 28 2023

...FROST ADVISORY REMAINS IN EFFECT UNTIL 10 AM PDT THIS
MORNING...

* WHAT...Temperatures of 36 or lower will result in frost 
  formation.

* WHERE...North Bay Interior Valleys.

* WHEN...From 1 AM to 10 AM PDT Saturday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

CAZ502-504-512-514-515-281545-
/O.CON.KMTR.WI.Y.0018.231028T1500Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
1241 AM PDT Sat Oct 28 2023

...WIND ADVISORY REMAINS IN EFFECT FROM 8 AM THIS MORNING TO 5 PM
PDT SUNDAY...

* WHAT...North to northeast winds of 20 to 30 mph with gusts up 
  to 45 mph expected. Ridgetop gusts over 50 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...From 8 AM Saturday to 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

* ADDITIONAL DETAILS...Critical fire weather conditions are
  expected in these areas and a Red Flag warning is also in
  effect.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

541 
WWUS76 KMTR 280828
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
128 AM PDT Sat Oct 28 2023

CAZ506-281700-
/O.CON.KMTR.FR.Y.0017.000000T0000Z-231028T1700Z/
North Bay Interior Valleys-
128 AM PDT Sat Oct 28 2023

...FROST ADVISORY REMAINS IN EFFECT UNTIL 10 AM PDT THIS
MORNING...

* WHAT...Temperatures of 36 or lower will result in frost 
  formation.

* WHERE...North Bay Interior Valleys.

* WHEN...From 1 AM to 10 AM PDT Saturday.

* IMPACTS...Frost could kill sensitive outdoor vegetation if 
  left uncovered.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold.

&&

$$

CAZ502-504-512-514-515-281800-
/O.CON.KMTR.WI.Y.0018.231028T1500Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
128 AM PDT Sat Oct 28 2023

...WIND ADVISORY REMAINS IN EFFECT FROM 8 AM THIS MORNING TO 5 PM
PDT SUNDAY...

* WHAT...North to northeast winds of 20 to 30 mph with gusts up 
  to 45 mph expected. Ridgetop gusts over 50 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...From 8 AM Saturday to 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

CAZ516-281800-
/O.NEW.KMTR.FZ.A.0006.231029T0900Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
128 AM PDT Sat Oct 28 2023

...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SUNDAY
MORNING...

* WHAT...Sub-freezing temperatures of 32 or colder possible.

* WHERE...Southern Salinas Valley, Arroyo Seco, and Lake San 
  Antonio.

* WHEN...From late tonight through Sunday morning.

* IMPACTS...Frost and freeze conditions could kill crops, other 
  sensitive vegetation and possibly damage unprotected outdoor 
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

239 
WWUS76 KMTR 281614
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
914 AM PDT Sat Oct 28 2023

CAZ506-281715-
/O.CAN.KMTR.FR.Y.0017.000000T0000Z-231028T1700Z/
North Bay Interior Valleys-
914 AM PDT Sat Oct 28 2023

...FROST ADVISORY IS CANCELLED...

Temperatures across the interior North Bay valleys are rising into
the low 40s, so Frost Advisory no longer necessary.

$$

CAZ502-504-512-514-515-290200-
/O.CON.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
914 AM PDT Sat Oct 28 2023

...WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM PDT SUNDAY...

* WHAT...North winds 20 to 30 mph with gusts up to 50 mph. 
  Ridgetop gusts over 60 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...Until 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

CAZ516-290200-
/O.CON.KMTR.FZ.A.0006.231029T0900Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
914 AM PDT Sat Oct 28 2023

...FREEZE WATCH REMAINS IN EFFECT FROM LATE TONIGHT THROUGH
SUNDAY MORNING...

* WHAT...Sub-freezing temperatures of 32 or colder possible.

* WHERE...Southern Salinas Valley, Arroyo Seco, and Lake San 
  Antonio.

* WHEN...From late tonight through Sunday morning.

* IMPACTS...Frost and freeze conditions could kill crops, other 
  sensitive vegetation and possibly damage unprotected outdoor 
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

182 
WWUS76 KMTR 281818
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
1118 AM PDT Sat Oct 28 2023

CAZ516-290600-
/O.UPG.KMTR.FZ.A.0006.231029T0900Z-231029T1500Z/
/O.NEW.KMTR.FZ.W.0012.231029T0900Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
1118 AM PDT Sat Oct 28 2023

...FREEZE WARNING IN EFFECT FROM 2 AM TO 8 AM PDT SUNDAY...

* WHAT...Freezing to sub-freezing temperatures 29-32 expected.

* WHERE...Southern Salinas Valley, Arroyo Seco, and Lake San 
  Antonio.

* WHEN...From 2 AM to 8 AM PDT Sunday.

* IMPACTS...Frost and freeze conditions will kill crops, other 
  sensitive vegetation and possibly damage unprotected outdoor 
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

CAZ502-504-512-514-515-290600-
/O.CON.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
1118 AM PDT Sat Oct 28 2023

...WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM PDT SUNDAY...

* WHAT...North winds 20 to 30 mph with gusts up to 50 mph. 
  Ridgetop gusts over 60 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...Until 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

476 
WWUS76 KMTR 290426
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
926 PM PDT Sat Oct 28 2023

CAZ516-291230-
/O.CON.KMTR.FZ.W.0012.231029T0900Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
926 PM PDT Sat Oct 28 2023

...FREEZE WARNING REMAINS IN EFFECT FROM 2 AM TO 8 AM PDT
SUNDAY...

* WHAT...Freezing to sub-freezing temperatures 29-32 expected.

* WHERE...Southern Salinas Valley, Arroyo Seco, and Lake San 
  Antonio.

* WHEN...From 2 AM to 8 AM PDT Sunday.

* IMPACTS...Frost and freeze conditions will kill crops, other 
  sensitive vegetation and possibly damage unprotected outdoor 
  plumbing.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

CAZ502-504-512-514-515-291230-
/O.CON.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
926 PM PDT Sat Oct 28 2023

...WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM PDT SUNDAY...

* WHAT...North winds 20 to 30 mph with gusts up to 50 mph. 
  Ridgetop gusts over 60 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...Until 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

159 
WWUS76 KMTR 291043
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
343 AM PDT Sun Oct 29 2023

CAZ516-291500-
/O.CON.KMTR.FZ.W.0012.000000T0000Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
343 AM PDT Sun Oct 29 2023

...FREEZE WARNING REMAINS IN EFFECT UNTIL 8 AM PDT THIS MORNING...

* WHAT...Freezing to sub-freezing temperatures 29-32 expected.

* WHERE...Southern Salinas Valley, Arroyo Seco, and Lake San 
  Antonio.

* WHEN...From 2 AM to 8 AM PDT Sunday.

* IMPACTS...Frost and freeze conditions will kill crops, other 
  sensitive vegetation and possibly damage unprotected outdoor 
  plumbing.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Take steps now to protect tender plants from the cold. To prevent
freezing and possible bursting of outdoor water pipes they should
be wrapped, drained, or allowed to drip slowly. Those that have
in-ground sprinkler systems should drain them and cover above-
ground pipes to protect them from freezing.

&&

$$

CAZ502-504-512-514-515-291500-
/O.CON.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
343 AM PDT Sun Oct 29 2023

...WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM PDT THIS
AFTERNOON...

* WHAT...North winds 20 to 30 mph with gusts up to 50 mph. 
  Ridgetop gusts over 60 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...Until 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

328 
WWUS76 KMTR 291453
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
753 AM PDT Sun Oct 29 2023

CAZ516-291600-
/O.EXP.KMTR.FZ.W.0012.000000T0000Z-231029T1500Z/
Southern Salinas Valley...Arroyo Seco...and Lake San Antonio-
753 AM PDT Sun Oct 29 2023

...FREEZE WARNING WILL EXPIRE AT 8 AM PDT THIS MORNING...

Temperatures continue to hover near freezing, but have been
gradually warming now that the sun has risen. Additional warming
is expected this morning. Therefore, the freeze warning will be 
allowed to expire.

$$

CAZ502-504-512-514-515-300000-
/O.CON.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
753 AM PDT Sun Oct 29 2023

...WIND ADVISORY REMAINS IN EFFECT UNTIL 5 PM PDT THIS
AFTERNOON...

* WHAT...North winds 20 to 30 mph with gusts up to 50 mph.
  Ridgetop gusts 60 to 70 mph possible.

* WHERE...Marin Coastal Range, North Bay Interior Mountains, 
  Santa Cruz Mountains, Eastern Santa Clara Hills and East Bay 
  Hills.

* WHEN...Until 5 PM PDT Sunday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Use extra caution when driving, especially if operating a high
profile vehicle. Secure outdoor objects.

&&

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

965 
WWUS76 KMTR 292112
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
212 PM PDT Sun Oct 29 2023

CAZ502-504-512-514-515-292215-
/O.CAN.KMTR.WI.Y.0018.000000T0000Z-231030T0000Z/
Marin Coastal Range-North Bay Interior Mountains-
Santa Cruz Mountains-Eastern Santa Clara Hills-East Bay Hills-
212 PM PDT Sun Oct 29 2023

...WIND ADVISORY IS CANCELLED...

Winds continue to diminish across the region and will continue to
diminish through this evening. However, breezy offshore winds with
gusts of 20 to 35 mph will still be possible.

$$

For more information from the National Weather Service visit
https://weather.gov/mtr

Area Forecast Discussion
National Weather Service San Francisco CA
1027 PM PDT Thu Oct 26 2023

...New AVIATION...

.SYNOPSIS...
Issued at 250 PM PDT Thu Oct 26 2023

Cold overnight lows expected through Saturday morning with patchy
frost possible in isolated, sheltered valleys of the North Bay.
This weekend, gusty offshore winds will set up across the region
which will result in elevated fire weather conditions. A Fire
Weather Watch is in effect for the North Bay interior mountains,
the East Bay Hills, the Eastern Santa Clara Hills, and the Santa
Cruz Mountains Saturday morning through Sunday evening.

&&

.UPDATE...
Issued at 857 PM PDT Thu Oct 26 2023

Skies are clearing as we head into a colder night. Lows in the
interior valleys are set to drop into the low 40s and upper 30s. The
overnight forecast team will make the final adjustments to overnight
temperatures and fine-tune Saturday morning's lows, while keeping an
eye on the frost risk. Additional attention will be payed to the
weekends fire wx risks, as higher resolution models begin to come
into range of the event.

&&

.SHORT TERM...
(This evening through Friday)
Issued at 250 PM PDT Thu Oct 26 2023

A cooler and drier airmass currently resides over the region as made
evident by the 12z OAK sounding, which shows 850 mb temps have
dropped 10 degrees in the last 24 hours. This in addition to light
offshore flow across the region has helped to eliminate the marine
layer inversion. Visible satellite shows clear skies across the
region but high clouds are approaching from the Pacific. Thanks
to the colder airmass, temperatures across the region today will
be running 5 to 10 degrees below seasonal norms with highs in the
upper 60s near the bay shoreline as well as the interior valleys.
Highs near the coast today will be in the upper 50s to low 60s.

Tonight will be another chilly night that will be a few degrees
colder than last night. The valleys of Sonoma County continue to
look like the coldest populated area in the cwa with lows dipping
again into the mid to upper 30s. Patchy frost will be possible
across sheltered valleys with lighter winds expected and clear
skies. It's not looking widespread or cold enough to issue the first
Frost Advisory of the season for the N Bay Valley zone tonight, but
some patchy frost is not out of the question for sheltered valleys
in the North Bay tonight. Another reason for not issuing a Frost
Advisory is the fact that there will be some high clouds that move
in over the Bay Area tonight, which will help to limit some
radiational cooling.

By Friday, the upper level longwave trough will start sliding south
into the Great Basin, which will set the stage for Saturday-Sunday's
fire weather concerns. Friday itself will feature rather benign
weather, though, with similar conditions to today but slightly
cooler.

&&

.LONG TERM...
(Friday night through next Wednesday)
Issued at 250 PM PDT Thu Oct 26 2023

Friday night through Saturday...

Colder temperatures expected again Friday night into Saturday
morning and forecasted to be slightly cooler than the previous
night. There will be more sites with temperature readings in the mid
30s Saturday morning and potentially more areas of frost across the
N Bay valleys. More confidence exists for Saturday morning to
potentially have the first Frost Advisory issuance, so stay tuned
for forecast updates. Less populated areas of the interior and
southern mountains (E Santa Clara Hills, San Benito Hills, S
Monterey County) could also see areas of frost Saturday morning.

Saturday through Monday...

Offshore winds are still on track to develop Saturday in wake of an
exiting (inside slider) trough and subsequent backdoor cold
frontal passage. Strong surface high pressure will build across
the Intermountain West Saturday night into Sunday, which will
serve to strengthen the offshore pressure gradient. SFO to
Winnemucca (WMC) forecasted offshore gradient is expected to be
impressively strong, reaching -14 mb per the GFS late Saturday
into Sunday.

As a result, dry conditions and north-northeasterly winds of 15
to 25 mph will develop first across the interior portions of our
forecast area (Napa Co, E Bay hills, and E Santa Clara Hills)
Saturday morning. Gusts of 35 to 45 mph possible across ridgetops.
By early Saturday afternoon, these gusty offshore winds will
spread to the Santa Cruz Mountains. The aforementioned regions are
now in a Fire Weather Watch which is valid from 5 AM Saturday
through 5 PM Sunday in coordination with neighboring NWS forecast
offices. See Fire Weather section below for a more detailed
analysis and overview of this upcoming offshore event.

By Monday, offshore winds linger but the speeds diminish greatly
as the SFO-WMC gradient diminishes. Upper level ridging builds in
and slightly warmer temperatures expected Monday, but still
looking near seasonable.

Tuesday-Wednesday...

Upper flow pattern becomes more zonal/westerly, which may open up
the door for some precip to move through. Will continue to
monitor.

&&

.AVIATION...
(06Z TAFS)
Issued at 1026 PM PDT Thu Oct 26 2023

High confidence that clear skies and VFR conditions prevail
through the TAF period. Generally light winds through the night,
with northwesterly flow at up to 10-15 knots developing Friday
afternoon.

Vicinity of SFO... VFR through the TAF period. West-northwest winds
diminishing through the night, light winds through Friday morning
before northwest winds gusting up to 10-15 knots build in the
afternoon.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR through the TAF period. Light drainage
winds overnight and into the morning, with breezy west-northwest
winds up to 8-12 knots Friday afternoon.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 857 PM PDT Thu Oct 26 2023

North to northwest winds weaken in the late night, but remain
strong along the southern coastal waters into early Friday. North
to northwest winds increase again elsewhere across the coastal
waters late in the week. Gusty winds will diminish on Sunday
leading to calm conditions into the next work week.

&&

.FIRE WEATHER...
Issued at 250 PM PDT Thu Oct 26 2023

Offshore wind setup slated for the weekend will bring elevated
fire weather conditions to the North Bay, East Bay hills, and the
Santa Cruz Mtns. Increasing confidence in the track of an upper
low through the Great Basin will cause a surface high pressure to
build across the interior regions Saturday. Ensemble guidance
advertising the SFO-WMC pressure gradient in the -12 to -14 mb
range during the time from about noon Saturday through noon
Sunday, which is approaching the 99th percentile. This set up
promotes widespread offshore flow with high confidence. Wind gusts
along ridgetops expected to be in the 35-45 mph range, with
moderate confidence that a few of the favored spots such as Mt.
St. Helena and Mt. Diablo could see gusts to 50 mph. Minimum RH
during the afternoons Saturday and Sunday will be in the 15-20%
range across much of the area as the downsloping offshore winds
increase. Overnight recoveries aren't much better between 25-45%.

The limiting factors with this event are related to the fuel
conditions and the degree of stability in the valleys. In regards
to the fuels, there is less concern in the more dense 100 and 1000
hour fuels as much of the moisture is still retained from recent
rains. Much more concern lies in the finer, more flashy fuels,
such as grasses and shrubbery. Stability presents some degree of
uncertainty to the wind forecast in valley areas. These areas are
still expected to be breezy through the weekend, but not as high
as their adjacent mountains and hills. If the valleys are able to
hold on to their moisture a little longer with weaker flow near
the surface, the atmosphere would remain largely decoupled and
the highest gusts would remain in the higher terrain. The worst
case scenario would be the stability completely eroding allowing
the highest gusts to mix down into the valley floors. We will be
keeping a close eye on this over the coming shifts and update the
forecast as needed.

&&

.CLIMATE...
Issued at 512 PM PDT Thu Oct 26 2023

Record low temperatures at the long term sites:

Station                 Oct 27th                Oct 28th

Santa Rosa              28 in 1919              28 in 1946
Kentfield               34 in 1919              34 in 1923, 1919
Napa                    34 in 1918              31 in 1946
Richmond                43 in 1984, 1970        41 in 1956
Livermore               30 in 1946              30 in 1946
San Francisco downtown  47 in 1984, 1908, 1893  46 in 1971
SFO Airport             42 in 1954, 1951        40 in 1954
Redwood City            39 in 1931              33 in 1946
Half Moon Bay           37 in 2022              37 in 1946
Oakland downtown        46 in 2010, 2004, 1975  44 in 1975
San Jose                37 in 1893              35 in 1946, 1894
Gilroy                  30 in 1967              30 in 1967
Salinas Airport         34 in 1931              32 in 1946
King City               30 in 1970, 1929        29 in 1984, 1970

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Fire Weather Watch from late Friday night through Sunday
     afternoon for CAZ502-504-512-514-515.

PZ...Small Craft Advisory from 3 PM to 9 PM PDT Friday for PZZ535.

     Small Craft Advisory until 3 AM PDT Saturday for PZZ565.

&&

SHORT TERM...McCorkle
LONG TERM....McCorkle
AVIATION...DialH
MARINE...Murdock

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