Red Flag Warning 4, NWS San Francisco Bay Area, CA

141 
WWUS86 KMTR 071123
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
423 AM PDT Mon Sep 7 2020

.A Red Flag Warning remains in effect for the North Bay Mountains
and East Bay Hills from 10 PM Monday to 8 AM Wednesday. In 
addition, a Red Flag Warning is in effect for the Santa Cruz 
Mountains from 10 AM Tuesday to 8 AM Wednesday. After low pressure
drops over the Intermountain West beginning late Monday, winds 
will shift to the north-northeast and becoming gusty in the North 
and East Bay Hills by Monday evening and in the Santa Cruz 
Mountains by Tuesday morning. Locally gusty offshore winds will 
then continue at times in the North and East Bay Hills and Santa 
Cruz Mountains through Wednesday morning. In conjunction with 
these locally gusty offshore winds, poor overnight humidity 
recoveries are expected with the absence of a marine layer. 
Humidities will drop into the teens during the daytime hours.

CAZ507-511-071930-
/O.CON.KMTR.FW.W.0004.200908T0500Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
423 AM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 PM THIS EVENING TO
8 AM PDT WEDNESDAY FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR
FIRE WEATHER ZONES 507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated
  peaks and ridgetops may approach 65 mph in the North Bay. 
  Strongest winds expected late Monday night and Tuesday morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly.
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

CAZ512-071930-
/O.CON.KMTR.FW.W.0004.200908T1700Z-200909T1500Z/
Santa Cruz Mountains-
423 AM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 AM TUESDAY TO 8 AM
PDT WEDNESDAY FOR LOCALLY GUSTY WINDS AND DRY CONDITIONS FOR FIRE
WEATHER ZONE 512...

* AFFECTED AREA...Santa Cruz Mountains above 1000 feet. Fire 
  weather zone 512. 

* WIND...Sustained north to northeast winds 10 to 20 mph with 
  gusts 25 to 35 mph above 1000 feet. Strongest winds expected 
  on Tuesday.

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Highest peaks, especially along the Santa 
  Cruz/Santa Clara county line.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

998 
WWUS86 KMTR 071906
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
1206 PM PDT Mon Sep 7 2020

.A Red Flag Warning remains in effect for the North Bay Mountains
and East Bay Hills from 10 PM Monday to 8 AM Wednesday. In 
addition, a Red Flag Warning is in effect for the Santa Cruz 
Mountains from 10 AM Tuesday to 8 AM Wednesday. After low pressure
drops over the Intermountain West beginning late Monday, winds 
will shift to the north-northeast and becoming gusty in the North 
and East Bay Hills by Monday evening and in the Santa Cruz 
Mountains by Tuesday morning. Locally gusty offshore winds will 
then continue at times in the North and East Bay Hills and Santa 
Cruz Mountains through Wednesday morning. In conjunction with 
these locally gusty offshore winds, poor overnight humidity 
recoveries are expected with the absence of a marine layer. 
Humidities will drop into the teens during the daytime hours.

CAZ507-511-080400-
/O.CON.KMTR.FW.W.0004.200908T0500Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
1206 PM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 PM THIS EVENING TO
8 AM PDT WEDNESDAY FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR
FIRE WEATHER ZONES 507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with 
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated 
  peaks and ridgetops may approach 65 mph in the North Bay. 
  Strongest winds expected late Monday night and Tuesday 
  morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

CAZ512-080400-
/O.CON.KMTR.FW.W.0004.200908T1700Z-200909T1500Z/
Santa Cruz Mountains-
1206 PM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 AM TUESDAY TO 8 AM
PDT WEDNESDAY FOR LOCALLY GUSTY WINDS AND DRY CONDITIONS FOR FIRE
WEATHER ZONE 512...

* AFFECTED AREA...Santa Cruz Mountains above 1000 feet. Fire 
  weather zone 512. 

* WIND...Sustained north to northeast winds 10 to 20 mph with 
  gusts 25 to 35 mph above 1000 feet. Strongest winds expected 
  on Tuesday.

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Highest peaks, especially along the Santa 
  Cruz/Santa Clara county line.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

984 
WWUS86 KMTR 080256
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
756 PM PDT Mon Sep 7 2020

.A Red Flag Warning remains in effect for the North Bay Mountains
and East Bay Hills from 10 PM Monday to 8 AM Wednesday. In 
addition, a Red Flag Warning is in effect for the Santa Cruz 
Mountains from 10 AM Tuesday to 8 AM Wednesday. After low pressure
drops over the Intermountain West beginning late Monday, winds 
will shift to the north-northeast and becoming gusty in the North 
and East Bay Hills by Monday evening and in the Santa Cruz 
Mountains by Tuesday morning. Locally gusty offshore winds will 
then continue at times in the North and East Bay Hills and Santa 
Cruz Mountains through Wednesday morning. In conjunction with 
these locally gusty offshore winds, poor overnight humidity 
recoveries are expected with the absence of a marine layer. 
Humidities will drop into the teens during the daytime hours.

CAZ507-511-081200-
/O.CON.KMTR.FW.W.0004.200908T0500Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
756 PM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 AM PDT WEDNESDAY
FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR FIRE WEATHER ZONES
507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with 
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated 
  peaks and ridgetops may approach 65 mph in the North Bay. 
  Strongest winds expected late Monday night and Tuesday 
  morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible on Tuesday.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

CAZ512-081200-
/O.CON.KMTR.FW.W.0004.200908T1700Z-200909T1500Z/
Santa Cruz Mountains-
756 PM PDT Mon Sep 7 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 AM TUESDAY TO 8 AM
PDT WEDNESDAY FOR LOCALLY GUSTY WINDS AND DRY CONDITIONS FOR FIRE
WEATHER ZONE 512...

* AFFECTED AREA...Santa Cruz Mountains above 1000 feet. Fire 
  weather zone 512. 

* WIND...Sustained north to northeast winds 10 to 20 mph with 
  gusts 25 to 35 mph above 1000 feet. Strongest winds expected 
  on Tuesday.

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Highest peaks, especially along the Santa 
  Cruz/Santa Clara county line.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

132 
WWUS86 KMTR 081132
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
432 AM PDT Tue Sep 8 2020

.A Red Flag Warning remains in effect for the North Bay Mountains
and East Bay Hills until 8 AM Wednesday. In addition, a Red Flag 
Warning is in effect for the Santa Cruz Mountains from 10 AM 
Tuesday to 8 AM Wednesday. North-northeast gusty winds in the 
North and East Bay Hills and in the Santa Cruz Mountains by 
Tuesday morning. Locally gusty offshore winds will then continue 
at times in the North and East Bay Hills and Santa Cruz Mountains 
through Wednesday morning. In conjunction with these locally gusty
offshore winds, poor overnight humidity recoveries are expected 
with the absence of a marine layer. Humidities will drop into the 
teens during the daytime hours.

CAZ507-511-082200-
/O.CON.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
432 AM PDT Tue Sep 8 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 AM PDT WEDNESDAY
FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR FIRE WEATHER ZONES
507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with 
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated 
  peaks and ridgetops may approach 65 mph in the North Bay. 
  Strongest winds expected late Monday night and Tuesday 
  morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible on Tuesday.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

CAZ512-082200-
/O.CON.KMTR.FW.W.0004.200908T1700Z-200909T1500Z/
Santa Cruz Mountains-
432 AM PDT Tue Sep 8 2020

...RED FLAG WARNING REMAINS IN EFFECT FROM 10 AM THIS MORNING TO
8 AM PDT WEDNESDAY FOR LOCALLY GUSTY WINDS AND DRY CONDITIONS FOR
FIRE WEATHER ZONE 512...

* AFFECTED AREA...Santa Cruz Mountains above 1000 feet. Fire 
  weather zone 512. 

* WIND...Sustained north to northeast winds 10 to 20 mph with 
  gusts 25 to 35 mph above 1000 feet. Strongest winds expected 
  on Tuesday.

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Highest peaks, especially along the Santa 
  Cruz/Santa Clara county line.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

748 
WWUS86 KMTR 082149
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
249 PM PDT Tue Sep 8 2020

.A Red Flag Warning remains in effect for the North Bay 
Mountains, East Bay Hills, and the Santa Cruz Mountains until 
8 AM Wednesday for strong and gusty north-northeast winds and  
dry conditions. Locally gusty offshore winds will continue  
across the North and East Bay Hills and Santa Cruz Mountains 
through Wednesday morning. In conjunction with these locally  
gusty offshore winds, poor overnight humidity recoveries are 
expected with the absence of a marine layer. Humidities will  
drop into the teens during the daytime hours.

CAZ507-511-091500-
/O.CON.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
249 PM PDT Tue Sep 8 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 AM PDT WEDNESDAY
FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR FIRE WEATHER ZONES
507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated
  peaks and ridgetops may approach 65 mph in the North Bay.
  Strongest winds expected late tonight and early Wednesday
  morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. Daytime
  humidity values 10 to 20.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

CAZ512-091500-
/O.CON.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
Santa Cruz Mountains-
249 PM PDT Tue Sep 8 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 AM PDT WEDNESDAY
FOR LOCALLY GUSTY WINDS AND DRY CONDITIONS FOR FIRE WEATHER ZONE
512...

* AFFECTED AREA...Santa Cruz Mountains above 1000 feet. Fire 
  weather zone 512. 

* WIND...Sustained north to northeast winds 10 to 20 mph with
  gusts 25 to 35 mph above 1000 feet. Strongest winds expected
  this evening.

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20, locally lower values 
  possible.

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Highest peaks, especially along the Santa 
  Cruz/Santa Clara county line.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

213 
WWUS86 KMTR 090819
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
119 AM PDT Wed Sep 9 2020

Default overview section
CAZ512-090930-
/O.CAN.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
Santa Cruz Mountains-
119 AM PDT Wed Sep 9 2020

...RED FLAG WARNING IS CANCELLED FOR LOCALLY GUSTY WINDS FOR FIRE
WEATHER ZONE 512...

THE NATIONAL WEATHER SERVICE IN San Francisco HAS CANCELLED THE
Red Flag Warning. 

Dry conditions continue over the Santa Cruz Mountains. However,
winds have weakened considerably, so the Red Flag Warning
cancelled early. Relative humidities remain dry at higher
elevations and are not expected to recover much overnight tonight.

$$

CAZ507-511-091500-
/O.CON.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
119 AM PDT Wed Sep 9 2020

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 8 AM PDT THIS MORNING
FOR STRONG WIND GUSTS AND DRY CONDITIONS FOR FIRE WEATHER ZONES 
507 AND 511...

* WIND...Sustained north to northeast winds 15 to 25 mph with
  gusts 30 to 45 mph above 1000 feet. Local gusts at isolated
  peaks and ridgetops may approach 50 mph in the North Bay. Winds
  are expected to gradually subside as the strongest winds were
  forecast for Tuesday evening into early Wednesday morning. 

* HUMIDITY...Poor overnight recoveries 20 to 35 percent. 
  Daytime humidity values 10 to 20. 

* IMPACTS...Any fires that develop will likely spread rapidly. 
  Follow all burn bans currently in effect.

* HIGHEST THREAT...Interior higher terrain of the North Bay 
  Mountains and the East Bay Hills.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Red Flag Warning means that critical fire weather conditions
are either occurring now...or will shortly. A combination of
strong winds...low relative humidity...and warm temperatures can
contribute to extreme fire behavior.

&&

$$

933 
WWUS86 KMTR 091439
RFWMTR

URGENT - FIRE WEATHER MESSAGE
National Weather Service San Francisco Bay Area
739 AM PDT Wed Sep 9 2020

CAZ507-511-091545-
/O.EXP.KMTR.FW.W.0004.000000T0000Z-200909T1500Z/
North Bay Mountains-East Bay Hills and the Diablo Range-
739 AM PDT Wed Sep 9 2020

...RED FLAG WARNING WILL EXPIRE AT 8 AM PDT THIS MORNING FOR
STRONG WIND GUSTS AND DRY CONDITIONS FOR FIRE WEATHER ZONES
507 AND 511...

Breezy and gusty north to northeast winds will continue to 
diminish this morning, allowing the Red Flag Warning to expire. 
However, critically dry conditions will prevail through Wednesday
with a wind shift out of the south to southwest becoming locally
gusty midday through Wednesday afternoon.

$$

Area Forecast Discussion
National Weather Service San Francisco Bay Area
215 PM PDT Sun Sep 6 2020

.SYNOPSIS...Hot to very hot temperatures are forecast through the
rest of this Labor Day weekend, with record breaking max temps
expected today and Monday when the warmest interior locations are
forecast to exceed 110 F. An Excessive Heat Warning is in effect
for all interior locations as well as the San Francisco Bay
Shoreline (excluding the City of San Francisco), and also the
Santa Cruz County Coast through 9 PM Monday. A Heat Advisory is in
effect for all other coastal areas through 9 PM Monday. Winds
will be light through Monday, but gusty offshore winds are
possible in the hills starting Monday evening, mainly at higher
elevations in the North and East Bay Hills. Warm conditions will
persist through much of next week, but temperatures are expected
to trend gradually downward from Tuesday onward.

&&

.DISCUSSION...as of 02:10 PM PDT Sunday...It's hot. The
culmination of the warm start to the day and the weak onshore flow
has made for quite the temperature gradient between the coast and
immediate interior. This is rather apparent in Santa Cruz County,
where temps along the beach are in the mid-70s F while widespread
100s F are being observed north of highway one, while some
locations along highway 17 are nearing the 110 F mark! Weak
onshore flow has also resulted in a similar situation in SF, where
neighborhoods like the Sunset District on the west side of the
City are in the 80s while the east side (e.g. Mission and Castro)
are looking to surpass the 100-degree mark. In all of these
instances we see how critical both the marine layer and onshore
winds are at keeping coastal locations cool given that it behaves
like a natural AC. Unfortunately, the AC is broken.

As for the interior, San Jose and indeed the entire Santa Clara
Valley is over 100 F, while 105-110 F are currently being observed
in all the higher- terrain stations and most of the interior
valleys. Up in the North Bay, Napa has made it up to 108 F as of
1:30PM while on the other side of the CWA Corralitos, one of our
RTP sites, has already made it to 112 F today. Several record high
temps for the day seem to be in jeopardy today as well, including
but not limiting DT San Francisco, which is well past the record
of 92 F set in 1904 after going over 93 F at 11:45AM and so far
has maxed out at 98 F. Even Half Moon Bay, which is one of our
coolest stations, made it up to 81 F just before 2PM, which means
it surpassed its record high of 80 F set back in 2004. For Labor
Day, onshore flow is forecast to return near the coast at some
point in the day and should allow for some cooling. However,
widespread 90s just a few miles inland and triple digits are again
expected across the interior. Thus, the Excessive Heat Warning and
Heat Advisory remains in effect through Monday evening.

Haze has also been reported all across the CWA, resulting in
declining air quality conditions for large swaths of the CWA due
to smoke from both the Dolan and Creek fires, the latter of which
has produced an enormous plume over much of the State. Given the
sharp vertical temperature inversion over the coast and near-
coastal locations, and the elevated smoke that has been stuck over
the area since last week, air quality concerns will continue.
Smoke may not help cool us much either, given that it's
predominantly the hot air mass and not so much the diurnal heating
that has aided in making it this hot all the way down to the
coast.

For more information on air quality concentrations, please refer
to the Bay Area Air Quality District. And for the latest on the
firefighting efforts across the State, including the new Creek
fire, please refer to CALFIRE.

Last night's poor humidity and temperature recoveries can be
expected again tonight given the light onshore winds and the
dominance of the hot, stable air mass. Thankfully, the 600dam
500hPa ridge over the Southwest won't be around for much longer,
as it begins to weaken and lose its amplitude, making way for an
upper-level trough that'll begin descending into the Mountain West
from Canada. This will translate into a notably cooler air mass
overhead and a gradual drop in temperatures across both the
interior and the coast in the coming days. That's the good news.

The bad news: as the trough quickly deepens and takes the place
of the ridge, its positively tilted axis will place us in its
convergent side going into Monday night and through Wednesday
morning. As it does so, offshore north and northeasterly flow
looks progged to mix down to some of our higher-terrain locations
above 1000+ ft. Short- range models suggesting winds in those
spots making into the 15-25 mph range, with gusts between 25-45
mph possible and even up to 50 mph in some isolated locations,
strongest in the interior North Bay and East Bay Mountains.

For a more detailed fire weather discussion, please refer to the
discussion below.

Looking ahead into the second half of the week, GEFS and EPS
guidance both lean towards an omega block set up that will keep a
PAC ridge lodged off the PAC NW coast while the center of the
Mountain West trough gradually moves east of the Front Range. As
the ridge moves ashore and the trough on the west side of the
Omega Block gradually moves closer to the coastline, cyclonic
flow could result in the resurgence of southerly surface flow.
Still out by a few days so low confidence at this time but it
would be beneficial in helping us cool down. Stay tuned.

.&&

.FIRE WEATHER...As of 5:37 AM PDT Sunday...A large area of high
pressure parked over the West will bring excessive heat and very
dry conditions over the district both day and night through at
least Monday. Triple digit heat will occur over the interior with
RH in the teens. Slightly cooler temperatures near the coast, but
still above normal and dry. Fortunately, winds will not be overly
strong through Monday, but some breezy conditions may develop
each afternoon. The extreme heat will help to erase any lingering
moisture from the marine layer in the finer fuels. BIs and ERCs
will both increase.

A classic watch out situation for fire weather is the break down
of the high pressure. In this case, the high pressure weakens on
Monday as a trough sweeps into the Intermountain West. This trough
deepens and becomes a low pressure system near the Four Corners
region. While this pattern is more "fall like", its impacts will
still be of great concern given the preceeding heatwave. Latest
pressure gradient metrics all point to a moderate offshore event
beginning Monday night and continuing through early Wednesday.
One pressure gradient that we use is SFO(CA)-WMC(NV). Anything
greater than 10 mb is something to watch and 15 mb or more is a
heads up situation. The latest models guidance suggests a pressure
gradient around 15 mb. Additionally, the SAC-RDD is decent as well
showing winds will be gusty in the valley too. Winds appear to be
strongest over the North Bay Mts with slightly weaker winds over
the East Bay Hills/Santa Cruz. Wind gusts of between 25 and 35 mph
are likely in the hills of the North and East Bay late Monday
night and Tuesday morning, with gusts of 40 to 50 mph possible
across northern Napa and northeast Sonoma Counties. Santa Cruz is
closer to 10 to 20 mph with gusts 30 mph. Winds will subside a
little during the day Tuesday, but then increase again Tuesday
night.

Gusty offshore winds after three days of excessive heat, combined
with very dry fuels, will create critical fire weather conditions
and explosive fire growth potential. A Fire Weather Watch is in
effect for elevations above 1000 feet in the North/East Bay and
Santa Cruz from Monday Evening through Wednesday Morning. This
Fire Weather Watch will likely be upgraded to a Red Flag Warning
on Sunday.

Winds are expected to ease in all areas by Wednesday afternoon and
temperatures will gradually cool from Tuesday through Thursday.
However, warm and dry conditions will persist across inland areas
through most of next week.

&&

.AVIATION...As of 11:00 AM PDT Sunday...for the 18Z TAFs. Extreme
hot and dry air mass over the region has left no marine layer in
place, thus widespread VFR aside from SMOKE visibility impacts
from numerous wildfires across the state. Light winds except
locally breezy this afternoon alongshore and through coastal
gaps such as near KSFO.

Vicinity of KSFO...VFR throughout the day with clear skies.
Periods of lower vis due to smoke and haze. Calm to light winds
through the morning turning onshore and increasing in the
afternoon around 15 to 20 kt. Winds easing overnight with clear
skies continuing.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR throughout the period with
occasional vis issues due to wildfire smoke/haze. Calm to light
winds through the morning turning onshore around 6-12 kt for the
afternoon. Easing winds overnight with generally clear skies.

&&

.CLIMATE...Record high temperatures for the Sunday and Labor Day

..................Sept 6.........Sept 7
---------------------------------------------

Santa Rosa.......106, 1904......108, 1904
Kentfield........104, 1923......104, 1923
Napa.............106, 1904......110, 1904
Richmond..........91, 2004.......93, 2015
Livermore........108, 1904......108, 1904
San Francisco.....92, 1904......100, 1904
SFO...............94, 2004.......93, 1957
Redwood City.....100, 1958.......99, 1982
Half Moon Bay.....80, 2004.......76, 2013
Oakland Dtown.....95, 1979.......93, 2015
San Jose.........100, 1923......106, 1904
Gilroy...........104, 1977......103, 1977
Santa Cruz........98, 2004......108, 1904
Salinas...........97, 2004.......99, 1957
Monterey..........94, 2004.......92, 1957
King City........105, 1928......106, 1936

&&

.MARINE...as of 08:52 AM PDT Sunday...Broadly weak northwest flow
except locally stronger winds along the coast jets at and to the
south of Pigeon Point and Point Sur through the extended weekend.
A light long period southerly swell will mix with a shorter period
northwest swell.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
     .Tngt...Excessive Heat Warning...CAZ506>508-510>513-516>518-528-529
             Heat Advisory...CAZ006-505-509-530
             SCA...Pigeon Pt to Pt Pinos 0-10 nm
             SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm

&&

PUBLIC FORECAST: Diaz/RGass
AVIATION: DRP
MARINE: DRP
FIRE WEATHER: MM

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