Alert archive / California / Wind Advisories in 2020

Wind Advisory 6, NWS San Francisco Bay Area, CA

September 7, 2020

NWS San Francisco Bay Area, CA issued this wind advisory at Sep 7, 2020, 2:45 AM PDT. It took effect at Sep 8, 2020, 5:00 AM PDT. It was in force for 18 hr.

The area

The counties it named.

The facts

Issued
Sep 7, 2020, 2:45 AM PDT (09:45 UTC)
In effect from
Sep 8, 2020, 5:00 AM PDT
Expired
Sep 8, 2020, 11:00 PM PDT
In force
18 hr
Issued by
NWS San Francisco Bay Area, CA

The text

As transmitted.

931 
WWUS76 KMTR 070945
NPWMTR

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

...Prolonged Period of Potentially Dangerous Heat to continue
through Labor Day across Interior Portions of the San Francisco
Bay Area and Central Coast...

...Gusty offshore winds will develop on Tuesday and be strongest
over the North Bay Mountains...

CAZ507-072200-
/O.NEW.KMTR.WI.Y.0006.200908T1200Z-200909T0600Z/
/O.CON.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
North Bay Mountains-
Including the cities of Angwin, Lagunitas-Forest Knolls, 
and Woodacre
245 AM PDT Mon Sep 7 2020

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT THIS
EVENING...
...WIND ADVISORY IN EFFECT FROM 5 AM TO 11 PM PDT TUESDAY...

* WHAT...Heat Warning- High temperatures Monday in the upper 90s
  to 114 degrees. Wind Advisory - north to northeast winds 15 to 
  30 mph with gusts up to 45-65 mph expected. Locally up to 70 mph
  near Mt St Helena.

* WHERE...North Bay Mountains.

* WHEN...For the Excessive Heat Warning, until 9 PM PDT this 
  evening. For the Wind Advisory, from 5 AM to 11 PM PDT Tuesday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result. Extreme heat and humidity will significantly increase 
  the potential for heat related illnesses, particularly for 
  those working or participating in outdoor activities.

* ADDITIONAL DETAILS...High pressure over the region will keep a
  stagnant air pattern in place. With wildfires still burning
  around the region, smoke and haze will still be around the
  region. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

CAZ506-508-510>513-516>518-528-529-072200-
/O.CON.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
North Bay Interior Valleys-San Francisco Bay Shoreline-
East Bay Interior Valleys-East Bay Hills and the Diablo Range-
Santa Cruz Mountains-Santa Clara Valley Including San Jose-
Southern Salinas Valley/Arroyo Seco and Lake San Antonio-
Santa Lucia Mountains and Los Padres National Forest-
Mountains Of San Benito County And Interior Monterey County
Including Pinnacles National Park-
Northern Salinas Valley/Hollister Valley and Carmel Valley-
Northern Monterey Bay-
Including the cities of Santa Rosa, South Santa Rosa, Napa, 
San Rafael, Petaluma, Novato, Rohnert Park, Oakland, Fremont, 
Hayward, Daly City, Berkeley, Concord, Antioch, Livermore, 
Walnut Creek, Pleasanton, Pittsburg, San Ramon, Blackhawk, 
Scotts Valley, Boulder Creek, Day Valley, San Jose, Greenfield, 
King City, Salinas, Santa Cruz, Watsonville, and Live Oak
245 AM PDT Mon Sep 7 2020

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT THIS
EVENING...

* WHAT...High temperatures Monday in the 90s in coastal areas and
  100 to 117 inland. 

* WHERE...All Interior locations as well as San Francisco Bay 
  Shoreline and Northern Monterey Bay.

* WHEN...Through 9 PM PDT Monday.

* IMPACTS...Heat related illnesses such as heat exhaustion and 
  heat stroke can occur due to prolonged exposure to hot 
  temperatures, even to the general population. People most 
  vulnerable include those who spend extended periods outdoors, 
  those without air conditioning, young children, the elderly, 
  and those with chronic illness.

* ADDITIONAL DETAILS...High pressure over the region will keep a
  stagnant air pattern in place. With wildfires still burning
  around the region, smoke and haze will still be around the
  region. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

CAZ006-505-509-530-072200-
/O.CON.KMTR.HT.Y.0005.000000T0000Z-200908T0400Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
Including the cities of San Francisco, Tamalpais-Homestead, 
Sausalito, Pacifica, Seaside, Monterey, and Marina
245 AM PDT Mon Sep 7 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 9 PM PDT THIS EVENING...

* WHAT...High temperatures on Monday from the upper 70s to mid 90s.
  

* WHERE...Coastal North Bay, San Francisco Peninsula Coast, and 
  Monterey to Big Sur.

* WHEN...Through 9 PM PDT Monday.

* IMPACTS...Heat related illnesses such as heat exhaustion and 
  heat stroke can occur due to prolonged exposure to hot 
  temperatures, even to the general population. People most 
  vulnerable include those who spend extended periods outdoors, 
  those without air conditioning, young children, the elderly, 
  and those with chronic illness.

* ADDITIONAL DETAILS...High pressure over the region will keep a
  stagnant air pattern in place. With wildfires still burning
  around the region, smoke and haze will still be around the
  region. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

For more information from the National Weather Service visit
http://weather.gov/mtr
4 follow-up statements
923 
WWUS76 KMTR 072024
NPWMTR

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

...Prolonged Period of Potentially Dangerous Heat to continue
through Labor Day across Interior Portions of the San Francisco
Bay Area and Central Coast...

...Gusty offshore winds will develop on Tuesday and be strongest
over the North Bay Mountains...

CAZ507-080400-
/O.CON.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
/O.CON.KMTR.WI.Y.0006.200908T1200Z-200909T0600Z/
North Bay Mountains-
Including the cities of Angwin, Lagunitas-Forest Knolls, 
and Woodacre
124 PM PDT Mon Sep 7 2020

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT THIS
EVENING...
...WIND ADVISORY REMAINS IN EFFECT FROM 5 AM TO 11 PM PDT
TUESDAY...

* WHAT...For the Excessive Heat Warning, high temperatures Monday
  in the upper 90s to 114 degrees. For the Wind Advisory, north 
  to northeast winds 15 to 30 mph with gusts up to 45-65 mph 
  expected. Locally up to 70 mph near Mt St Helena.

* WHERE...North Bay Mountains.

* WHEN...For the Excessive Heat Warning, until 9 PM PDT this 
  evening. For the Wind Advisory, from 5 AM to 11 PM PDT Tuesday.

* IMPACTS...Gusty winds could blow around unsecured objects. 
  Tree limbs could be blown down and a few power outages may 
  result. Extreme heat and humidity will significantly increase 
  the potential for heat related illnesses, particularly for 
  those working or participating in outdoor activities.

* ADDITIONAL DETAILS...High pressure over the region will keep a 
  stagnant air pattern in place. With wildfires still burning 
  around the region, smoke and haze will still be around the 
  region.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

CAZ506-508-510>513-516>518-528-529-080400-
/O.CON.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
North Bay Interior Valleys-San Francisco Bay Shoreline-
East Bay Interior Valleys-East Bay Hills and the Diablo Range-
Santa Cruz Mountains-Santa Clara Valley Including San Jose-
Southern Salinas Valley/Arroyo Seco and Lake San Antonio-
Santa Lucia Mountains and Los Padres National Forest-
Mountains Of San Benito County And Interior Monterey County
Including Pinnacles National Park-
Northern Salinas Valley/Hollister Valley and Carmel Valley-
Northern Monterey Bay-
Including the cities of Santa Rosa, South Santa Rosa, Napa, 
San Rafael, Petaluma, Novato, Rohnert Park, Oakland, Fremont, 
Hayward, Daly City, Berkeley, Concord, Antioch, Livermore, 
Walnut Creek, Pleasanton, Pittsburg, San Ramon, Blackhawk, 
Scotts Valley, Boulder Creek, Day Valley, San Jose, Greenfield, 
King City, Salinas, Santa Cruz, Watsonville, and Live Oak
124 PM PDT Mon Sep 7 2020

...EXCESSIVE HEAT WARNING REMAINS IN EFFECT UNTIL 9 PM PDT THIS
EVENING...

* WHAT...High temperatures Monday in the 90s in coastal areas 
  and 100 to 117 inland.

* WHERE...All Interior locations as well as San Francisco Bay 
  Shoreline and Northern Monterey Bay.

* WHEN...Through 9 PM PDT Monday.

* IMPACTS...Heat related illnesses such as heat exhaustion and 
  heat stroke can occur due to prolonged exposure to hot 
  temperatures, even to the general population. People most 
  vulnerable include those who spend extended periods outdoors, 
  those without air conditioning, young children, the elderly, 
  and those with chronic illness.

* ADDITIONAL DETAILS...High pressure over the region will keep a 
  stagnant air pattern in place. With wildfires still burning 
  around the region, smoke and haze will still be around the 
  region.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

CAZ006-505-509-530-080400-
/O.CON.KMTR.HT.Y.0005.000000T0000Z-200908T0400Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
Including the cities of San Francisco, Tamalpais-Homestead, 
Sausalito, Pacifica, Seaside, Monterey, and Marina
124 PM PDT Mon Sep 7 2020

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 9 PM PDT THIS EVENING...

* WHAT...High temperatures on Monday from the upper 70s to mid 
  90s.

* WHERE...Coastal North Bay, San Francisco Peninsula Coast, and 
  Monterey to Big Sur.

* WHEN...Through 9 PM PDT Monday.

* IMPACTS...Heat related illnesses such as heat exhaustion and 
  heat stroke can occur due to prolonged exposure to hot 
  temperatures, even to the general population. People most 
  vulnerable include those who spend extended periods outdoors, 
  those without air conditioning, young children, the elderly, 
  and those with chronic illness.

* ADDITIONAL DETAILS...High pressure over the region will keep a 
  stagnant air pattern in place. With wildfires still burning 
  around the region, smoke and haze will still be around the 
  region.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Drink plenty of fluids, stay in an air-conditioned room, stay out
of the sun, and check up on relatives and neighbors. Young
children and pets should never be left unattended in vehicles
under any circumstances.

Take extra precautions if you work or spend time outside. When
possible reschedule strenuous activities to early morning or
evening. Know the signs and symptoms of heat exhaustion and heat
stroke. Wear lightweight and loose fitting clothing when
possible. To reduce risk during outdoor work, the Occupational
Safety and Health Administration recommends scheduling frequent
rest breaks in shaded or air conditioned environments. Anyone
overcome by heat should be moved to a cool and shaded location.
Heat stroke is an emergency! Call 9 1 1.

&&

$$

For more information from the National Weather Service visit
http://weather.gov/mtr
273 
WWUS76 KMTR 080403
NPWMTR

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

...Gusty offshore winds will develop Monday Night and Tuesday and
be strongest over the North Bay Mountains...

...Prolonged period of excessive heat coming to a gradual end...

CAZ507-081200-
/O.EXP.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
/O.CON.KMTR.WI.Y.0006.200908T1200Z-200909T0600Z/
North Bay Mountains-
Including the cities of Angwin, Lagunitas-Forest Knolls, 
and Woodacre
903 PM PDT Mon Sep 7 2020

...WIND ADVISORY REMAINS IN EFFECT FROM 5 AM TO 11 PM PDT
TUESDAY...
...EXCESSIVE HEAT WARNING EXPIRED AT 9 PM PDT THIS EVENING...

* WHAT...North winds 15 to 25 mph with gusts 35 to 45 mph
  expected. Gusts of 45 to 65 mph possible at the higher
  elevations of northern Napa and northeast Sonoma Counties.

* WHERE...North Bay Mountains.

* WHEN...From 5 AM to 11 PM PDT Tuesday.

* 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.

&&

$$

CAZ506-508-510>513-516>518-528-529-080515-
/O.EXP.KMTR.EH.W.0002.000000T0000Z-200908T0400Z/
North Bay Interior Valleys-San Francisco Bay Shoreline-
East Bay Interior Valleys-East Bay Hills and the Diablo Range-
Santa Cruz Mountains-Santa Clara Valley Including San Jose-
Southern Salinas Valley/Arroyo Seco and Lake San Antonio-
Santa Lucia Mountains and Los Padres National Forest-
Mountains Of San Benito County And Interior Monterey County
Including Pinnacles National Park-
Northern Salinas Valley/Hollister Valley and Carmel Valley-
Northern Monterey Bay-
Including the cities of Santa Rosa, South Santa Rosa, Napa, 
San Rafael, Petaluma, Novato, Rohnert Park, Oakland, Fremont, 
Hayward, Daly City, Berkeley, Concord, Antioch, Livermore, 
Walnut Creek, Pleasanton, Pittsburg, San Ramon, Blackhawk, 
Scotts Valley, Boulder Creek, Day Valley, San Jose, Greenfield, 
King City, Salinas, Santa Cruz, Watsonville, and Live Oak
903 PM PDT Mon Sep 7 2020

...EXCESSIVE HEAT WARNING EXPIRED AT 9 PM PDT THIS EVENING...

A gradual cooling trend is forecast through Thursday. Tuesday 
will still be a very warm to hot day across the interior, but 
Heat Risk is expected to diminish.

$$

CAZ006-505-509-530-080515-
/O.EXP.KMTR.HT.Y.0005.000000T0000Z-200908T0400Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
Including the cities of San Francisco, Tamalpais-Homestead, 
Sausalito, Pacifica, Seaside, Monterey, and Marina
903 PM PDT Mon Sep 7 2020

...HEAT ADVISORY EXPIRED AT 9 PM PDT THIS EVENING...

Onshore flow began to increase on Monday afternoon, bringing some
relief from the heat. Continued cooling is expected through
midweek. 

$$

For more information from the National Weather Service visit
http://weather.gov/mtr
868 
WWUS76 KMTR 081127
NPWMTR

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

...Gusty offshore winds will impact the North Bay Mountains...

...Prolonged period of excessive heat coming to a gradual end...

CAZ507-082200-
/O.CON.KMTR.WI.Y.0006.200908T1200Z-200909T0600Z/
North Bay Mountains-
Including the cities of Angwin, Lagunitas-Forest Knolls, 
and Woodacre
427 AM PDT Tue Sep 8 2020

...WIND ADVISORY REMAINS IN EFFECT UNTIL 11 PM PDT THIS EVENING...

* WHAT...North winds 15 to 25 mph with gusts 35 to 45 mph
  expected. Gusts of 45 to 65 mph possible at the higher 
  elevations of northern Napa and northeast Sonoma Counties.

* WHERE...North Bay Mountains.

* WHEN...From 5 AM to 11 PM PDT Tuesday.

* 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
http://weather.gov/mtr
305 
WWUS76 KMTR 090553
NPWMTR

URGENT - WEATHER MESSAGE
National Weather Service San Francisco Bay Area
1053 PM PDT Tue Sep 8 2020

CAZ507-090700-
/O.EXP.KMTR.WI.Y.0006.000000T0000Z-200909T0600Z/
North Bay Mountains-
Including the cities of Angwin, Lagunitas-Forest Knolls, 
and Woodacre
1053 PM PDT Tue Sep 8 2020

...WIND ADVISORY WILL EXPIRE AT 11 PM PDT THIS EVENING...

Northerly winds remain strong tonight at typically gusty 
locations like Pine Flat Road, Healdsburg Hills, Mt St Helena, and
Mt Diablo. With conditions as dry as the are, caution is still
advised this evening. However, winds are expected to slowly 
weaken over the next few hours. Therefore the Wind Advisory will 
be allowed to expire.

$$

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

What forecasters said that day

The local office's own words before this wind advisory went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS San Francisco Bay Area, CA wrote its last area forecast discussion before this wind advisory went out at Sep 6, 10:30 PM PDT, 4 hours 15 minutes earlier.

Area forecast discussion, Sep 6, 10:30 PM PDT, 4 hours 15 minutes before
Area Forecast Discussion
National Weather Service San Francisco Bay Area
1030 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 again on Monday when the warmest interior locations are
forecast to exceed 110 F. An Excessive Heat Warning remains 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
likely in the hills starting Monday evening, mainly at higher
elevations in the North and East Bay Hills. Warm conditions will
persist through much of the week, but temperatures are expected
to trend gradually downward from Tuesday onward.

&&

.DISCUSSION...As of 9:20 PM PDT Sunday...Widespread record
breaking heat occurred across the SF Bay Area and Central Coast
today. High temperatures ranged from mild 70s at the ocean
beaches to 100 degrees only a few miles away from the ocean in
Downtown San Francisco. Most of our forecast area experienced
triple digit heat today, with many inland valley locations
topping out over 110. The warmest spots were Pinnacles National
Park and Bradley (southern Salinas Valley) with afternoon highs of
117. Thirteen daily high temperature records were set today. In
addition, Napa, Kentfield, and Gilroy all tied their record highs
for the entire month of September.

Another day of record breaking heat is expected on Labor Day,
although coastal areas are expected to see slight relief from the
heat due to stronger onshore flow in the afternoon compared to
today. However, tomorrow will likely start out warmer than today
and temperatures will rise quickly in the morning prior to the
onset of the seabreeze. So places like Downtown San Francisco
could still easily reach 90 by midday. All locations away from the
coast will continue to experience oppressive heat tomorrow with
temperatures forecast to be within a few degrees of today's highs.
The combination of three consecutive days of very hot
temperatures, as well as limited overnight relief due to
temperatures only cooling into the upper 60s and 70s, will result
in high to very high Heat Risk for at least one more day across
nearly our entire forecast area. Excessive Heat Warnings and Heat
Advisories remain in effect through 9 PM Monday. The upper ridge
will begin to weaken by Tuesday and gradual cooling is anticipated
in all areas from Tuesday through the remainder of the week.

Primary forecast concern besides the heat continues to be the
likely development of gusty offshore winds in the hills starting
Monday night and continuing through early Wednesday. These gusty
offshore winds will bring even drier air into our region. The
combination of gusty winds and very dry air will generate critical
fire weather conditions in the hills of the San Francisco Bay
Area from Monday evening through Wednesday morning. See Fire
Weather Discussion below for more details.

&&

.PREVIOUS 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.

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 5:20 PM PDT Sunday...A large area of high
pressure parked over the West will continue to bring excessive
heat and very dry conditions to the entire district through at
least Monday. Triple digit heat will occur over the interior with
RH in the teens. Slightly cooler temperatures are forecast close
to the ocean, but still well above normal and dry. Fortunately,
winds will remain rather light through early Monday afternoon,
but northwest winds will begin to increase in the hills by late
Monday 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 by
late 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 wind event beginning Monday night and continuing through
early Wednesday. Winds will likely be strongest over the North
Bay Mountains with slightly weaker winds over the East Bay
Hills and Santa Cruz Mountains. 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. Northerly winds
in the Santa Cruz Mountains by late Tuesday morning are forecast
to range from 10 to 20 mph with gusts 30 mph. Winds will subside a
little on Tuesday afternoon and evening, but then increase again
Tuesday night. However, winds on Tuesday night are not expected to
be as strong as late Monday night and Tuesday morning. Offshore
flow will result in even lower relative humidity, with little or
no recovery expected in the hills Monday night and daytime values
on Tuesday expected to drop as low as the single digits.

Gusty offshore winds after three days of excessive heat, combined
with low humidity and very dry fuels, will create critical fire
weather conditions and explosive fire growth potential. The Fire
Weather Watch for the North Bay Mountains, East Bay Hills, and
Santa Cruz Mountains has been upgraded to a Red Flag Warning. The
Red Flag Warning for elevations above 1000 feet in the North and
East Bay is in effect from 10 PM Monday Evening through 8 AM
Wednesday Morning. The Red Flag Warning for the Santa Cruz
Mountains is in effect from 10 AM Tuesday Morning through 8 AM
Wednesday Morning.

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 10:30 PM PDT Sunday...For the 06Z TAFs, smoke
and haze will continue to reduce visibility across the region,
with areas of MVFR and local IFR possible. Breezy onshore winds
are beginning to ease and will become light and variable
overnight, with clear skies prevailing. Expect breezy onshore
winds to develop once again after 20z, especially along the coast
and through the gaps.

Vicinity of KSFO...VFR conditions will prevail with clear skies.
Periods of lower vis due to smoke and haze are possible. Breezy onshore
winds are beginning to ease this evening, but will redevelop once
again tomorrow afternoon.

SFO Bridge Approach...Similar to KSFO.

Monterey Bay Terminals...VFR throughout the period with occasional
vis issues due to wildfire smoke/haze. Light and variable winds
tonight will turn onshore and increase to around 6-12 kt Monday
afternoon.

&&

.CLIMATE...Record high temperatures for Labor Day

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

Santa Rosa........108, 1904
Kentfield.........104, 1923
Napa..............110, 1904
Richmond...........93, 2015
Livermore.........108, 1904
San Francisco.....100, 1904
SFO................93, 1957
Redwood City.......99, 1982
Half Moon Bay......76, 2013
Oakland Dtown......93, 2015
San Jose..........106, 1904
Gilroy............103, 1977
Santa Cruz........108, 1904
Salinas............99, 1957
Monterey...........92, 1957
King City.........106, 1936

&&

.MARINE...As of 8:55 PM PDT Sunday...Weak northwest flow across
the waters will continue, except  locally stronger winds along the
coast jets at and to the south of Pigeon Point and Point Sur
through this holiday 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: Dykema/Diaz/RGass
AVIATION: Palmer
MARINE: Palmer
FIRE WEATHER: MM/Dykema

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The office that day

Everything else NWS San Francisco Bay Area, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 7, 2:49 PM PDTSmall Craft AdvisoryMTR30 hr

Nearby

Wind Advisories in California, 2020Every wind advisory in 2020

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text.