Alert archive / California / High Surf Advisories in 2021

High Surf Advisory 4, NWS San Francisco Bay Area, CA

January 11, 20216 counties in California

NWS San Francisco Bay Area, CA issued this high surf advisory at Jan 11, 2021, 2:35 PM PST for 6 counties in California. It took effect at Jan 12, 2021, 10:00 AM PST. It was in force for 35 hr.

The area

The counties it named.

The facts

Issued
Jan 11, 2021, 2:35 PM PST (22:35 UTC)
In effect from
Jan 12, 2021, 10:00 AM PST
Expired
Jan 13, 2021, 9:00 PM PST
In force
35 hr
Issued by
NWS San Francisco Bay Area, CA

Counties City and County of San Francisco, CA, Marin County, CA, Monterey County, CA, San Mateo County, CA, Santa Cruz County, CA, Sonoma County, CA

The radar

The San Francisco radar (KMUX), 53 km from the middle of the area, began a volume at 22:36 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Oakland, CA (KOAK), launched 12:00Z, 10.6 hours before the alert went out and 26 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Oakland, CA at 12:00Z on 2021-01-11Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Oakland, CA at 12:00Z on 2021-01-11The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 1 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
1113 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
1 m²/s²
0-3 km storm-relative helicity
-44 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

740 
WHUS46 KMTR 112235
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
235 PM PST Mon Jan 11 2021

...KING TIDES WILL CAUSE MINOR COASTAL OVERFLOW AND FLOODING
TUESDAY MORNING...

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS 
CONDITIONS ALONG THE COAST TUESDAY THROUGH WEDNESDAY...

.Another large, long period northwest swell will impact the coast
from Tuesday morning through Wednesday afternoon with breaking
waves of 20 to 25 feet, locally up to 30 feet at favored
breakpoints. Initial forerunners of 4 to 6 feet at 20 to 22 
seconds will arrive Tuesday morning result in an increased risk 
for dangerous sneaker waves and rip currents. The swell and 
associated waves will build through the day Tuesday before peaking
Tuesday night. Additionally, high astronomical tides commonly 
referred to as King Tides will again impact the coast resulting 
in minor coastal flooding around the time of high tides on Tuesday
morning.

CAZ006-505-509-529-530-120700-
/O.NEW.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
/O.NEW.KMTR.SU.Y.0004.210112T1800Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
235 PM PST Mon Jan 11 2021

...COASTAL FLOOD ADVISORY IN EFFECT FROM 5 AM TO 1 PM PST
TUESDAY...
...HIGH SURF ADVISORY IN EFFECT FROM 10 AM TUESDAY TO 3 PM PST
WEDNESDAY...

* WHAT...For the Coastal Flood Advisory, minor coastal flooding
  expected. For the High Surf Advisory, large breaking waves of 20
  to 25 feet, locally up to 30 feet at favored breakpoints.
  Initial forerunners of 4 to 6 feet at 20 to 22 seconds will 
  arrive Tuesday morning result in an increased risk for dangerous
  sneaker waves. Additionally, these waves will result in an 
  increased risk of strong rip currents and coastal erosion.

* WHERE...San Francisco, Coastal North Bay Including Point Reyes 
  National Seashore, San Francisco Peninsula Coast, Northern 
  Monterey Bay and Southern Monterey Bay and Big Sur Coast.

* WHEN...For the Coastal Flood Advisory, from 5 AM to 1 PM PST 
  Tuesday. For the High Surf Advisory, from 10 AM Tuesday to 3 
  PM PST Wednesday.

* IMPACTS...Flooding of lots, parks, and roads with only isolated
  road closures expected. Large breaking waves can sweep people
  off jetties and rocks, and into the frigid and turbulent ocean
  water. Life-threatening swimming conditions and localized beach
  erosion can be expected. Cold water rescues or drownings are 
  more likely with these waves and stronger rip currents. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$

CAZ506-120700-
/O.NEW.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
North Bay Interior Valleys-
235 PM PST Mon Jan 11 2021

...COASTAL FLOOD ADVISORY IN EFFECT FROM 5 AM TO 1 PM PST
TUESDAY...

* WHAT...Minor coastal flooding expected.

* WHERE...Shorelines of the North San Francisco Bay and San Pablo
  Bay.

* WHEN...From 5 AM to 1 PM PST Tuesday.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

&&

$$
8 follow-up statements
537 
WHUS46 KMTR 120528
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
928 PM PST Mon Jan 11 2021

...KING TIDES WILL CAUSE MINOR COASTAL OVERFLOW AND FLOODING
TUESDAY MORNING...

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST TUESDAY THROUGH WEDNESDAY...

.Another large, long period northwest swell will impact the coast
from Tuesday morning through Wednesday afternoon with breaking
waves of 20 to 25 feet, locally up to 30 feet at favored
breakpoints. Initial forerunners of 4 to 6 feet at 20 to
22 seconds will arrive Tuesday morning result in an increased
risk for dangerous sneaker waves and rip currents. The swell and
associated waves will build through the day Tuesday before
peaking Tuesday night. Additionally, high astronomical tides
commonly referred to as King Tides will again impact the coast
resulting in minor coastal flooding around the time of high tides
on Tuesday morning.

CAZ006-505-509-529-530-121400-
/O.CON.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
/O.CON.KMTR.SU.Y.0004.210112T1800Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
928 PM PST Mon Jan 11 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT FROM 5 AM TO 1 PM PST
TUESDAY...
...HIGH SURF ADVISORY REMAINS IN EFFECT FROM 10 AM TUESDAY TO
3 PM PST WEDNESDAY...

* WHAT...For the Coastal Flood Advisory, minor coastal flooding 
  expected. For the High Surf Advisory, large breaking waves of 
  20 to 25 feet, locally up to 30 feet at favored breakpoints. 
  Initial forerunners of 4 to 6 feet at 20 to 22 seconds will 
  arrive Tuesday morning result in an increased risk for 
  dangerous sneaker waves. Additionally, these waves will result 
  in an increased risk of strong rip currents and coastal 
  erosion. 

* WHERE...San Francisco, Coastal North Bay Including Point Reyes 
  National Seashore, San Francisco Peninsula Coast, Northern 
  Monterey Bay and Southern Monterey Bay and Big Sur Coast. 

* WHEN...For the Coastal Flood Advisory, from 5 AM to 1 PM PST 
  Tuesday. For the High Surf Advisory, from 10 AM Tuesday to 3 
  PM PST Wednesday. 

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. Large breaking waves can 
  sweep people off jetties and rocks, and into the frigid and 
  turbulent ocean water. Life-threatening swimming conditions 
  and localized beach erosion can be expected. Cold water 
  rescues or drownings are more likely with these waves and 
  stronger rip currents. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$

CAZ506-121400-
/O.CON.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
North Bay Interior Valleys-
928 PM PST Mon Jan 11 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT FROM 5 AM TO 1 PM PST
TUESDAY...

* WHAT...Minor coastal flooding expected.

* WHERE...Shorelines of the North San Francisco Bay and San 
  Pablo Bay. 

* WHEN...From 5 AM to 1 PM PST Tuesday.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

&&

$$
170 
WHUS46 KMTR 121038
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
238 AM PST Tue Jan 12 2021

...KING TIDES WILL CAUSE MINOR COASTAL OVERFLOW AND FLOODING
TUESDAY MORNING...

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST TUESDAY THROUGH WEDNESDAY...

.Another large, long period northwest swell will impact the coast
from Tuesday morning through Wednesday afternoon with breaking
waves of 20 to 25 feet, locally up to 30 feet at favored
breakpoints. Initial forerunners of 4 to 6 feet at 20 to
22 seconds will arrive Tuesday morning result in an increased
risk for dangerous sneaker waves and rip currents. The swell and
associated waves will build through the day Tuesday before
peaking Tuesday night. Additionally, high astronomical tides
commonly referred to as King Tides will again impact the coast
resulting in minor coastal flooding around the time of high tides
on Tuesday morning.

CAZ006-505-509-529-530-122100-
/O.CON.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
/O.CON.KMTR.SU.Y.0004.210112T1800Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
238 AM PST Tue Jan 12 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT UNTIL 1 PM PST THIS
AFTERNOON...
...HIGH SURF ADVISORY REMAINS IN EFFECT FROM 10 AM THIS MORNING
TO 3 PM PST WEDNESDAY...

* WHAT...For the Coastal Flood Advisory, minor coastal flooding 
  expected. For the High Surf Advisory, large breaking waves of 
  20 to 25 feet, locally up to 30 feet at favored breakpoints. 
  Initial forerunners of 4 to 6 feet at 20 to 22 seconds will 
  arrive Tuesday morning result in an increased risk for 
  dangerous sneaker waves. Additionally, these waves will result 
  in an increased risk of strong rip currents and coastal 
  erosion.

* WHERE...San Francisco Peninsula Coast, San Francisco, Coastal 
  North Bay Including Point Reyes National Seashore, Southern 
  Monterey Bay and Big Sur Coast and Northern Monterey Bay.

* WHEN...For the Coastal Flood Advisory, until 1 PM PST this 
  afternoon. For the High Surf Advisory, from 10 AM this morning 
  to 3 PM PST Wednesday.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. Dangerous swimming and 
  surfing conditions and localized beach erosion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$

CAZ506-122100-
/O.CON.KMTR.CF.Y.0002.210112T1300Z-210112T2100Z/
North Bay Interior Valleys-
238 AM PST Tue Jan 12 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT UNTIL 1 PM PST THIS
AFTERNOON...

* WHAT...Minor coastal flooding expected.

* WHERE...Shorelines of the North San Francisco Bay and San 
  Pablo Bay.

* WHEN...Until 1 PM PST this afternoon.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

&&

$$
113 
WHUS46 KMTR 121857
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
1057 AM PST Tue Jan 12 2021

...KING TIDES WILL CAUSE MINOR COASTAL OVERFLOW AND FLOODING
TUESDAY MORNING...

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST TUESDAY THROUGH WEDNESDAY...

.Another large, long period northwest swell will impact the coast
from Tuesday morning through Wednesday afternoon with breaking
waves of 20 to 25 feet, locally up to 30 feet at favored
breakpoints. Initial forerunners of 4 to 6 feet at 20 to
22 seconds will arrive Tuesday morning result in an increased
risk for dangerous sneaker waves and rip currents. The swell and
associated waves will build through the day Tuesday before
peaking Tuesday night. Additionally, high astronomical tides
commonly referred to as King Tides will again impact the coast
resulting in minor coastal flooding around the time of high tides
on Tuesday morning.

CAZ006-505-509-529-530-130300-
/O.CON.KMTR.CF.Y.0002.000000T0000Z-210112T2100Z/
/O.CON.KMTR.SU.Y.0004.000000T0000Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
1057 AM PST Tue Jan 12 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT UNTIL 1 PM PST THIS
AFTERNOON...
...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 3 PM PST
WEDNESDAY...

* WHAT...For the Coastal Flood Advisory, minor coastal flooding 
  expected. For the High Surf Advisory, large breaking waves of 
  20 to 25 feet, locally up to 30 feet at favored breakpoints. 
  Initial forerunners of 4 to 6 feet at 20 to 22 seconds will 
  arrive Tuesday morning result in an increased risk for 
  dangerous sneaker waves. Additionally, these waves will result 
  in an increased risk of strong rip currents and coastal 
  erosion.

* WHERE...San Francisco Peninsula Coast, San Francisco, Coastal 
  North Bay Including Point Reyes National Seashore, Southern 
  Monterey Bay and Big Sur Coast and Northern Monterey Bay.

* WHEN...For the Coastal Flood Advisory, until 1 PM PST this 
  afternoon. For the High Surf Advisory, from 10 AM this morning 
  to 3 PM PST Wednesday.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. Dangerous swimming and 
  surfing conditions and localized beach erosion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$

CAZ506-122100-
/O.CON.KMTR.CF.Y.0002.000000T0000Z-210112T2100Z/
North Bay Interior Valleys-
1057 AM PST Tue Jan 12 2021

...COASTAL FLOOD ADVISORY REMAINS IN EFFECT UNTIL 1 PM PST THIS
AFTERNOON...

* WHAT...Minor coastal flooding expected.

* WHERE...Shorelines of the North San Francisco Bay and San 
  Pablo Bay.

* WHEN...Until 1 PM PST this afternoon.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

&&

$$
426 
WHUS46 KMTR 122200
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
200 PM PST Tue Jan 12 2021

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST TUESDAY THROUGH WEDNESDAY...

.Another large, long period northwest swell will impact the coast
from Tuesday morning through Wednesday afternoon with breaking
waves of 20 to 25 feet, locally up to 30 feet at favored
breakpoints. Initial forerunners of 4 to 6 feet at 20 to
22 seconds will arrive Tuesday morning result in an increased
risk for dangerous sneaker waves and rip currents. The swell and
associated waves will build through the day Tuesday before
peaking Tuesday night.

CAZ006-505-509-529-530-130600-
/O.CON.KMTR.SU.Y.0004.000000T0000Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
200 PM PST Tue Jan 12 2021

...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 3 PM PST
WEDNESDAY...

* WHAT...For the Coastal Flood Advisory, minor coastal flooding 
  expected. For the High Surf Advisory, large breaking waves of 
  20 to 25 feet, locally up to 30 feet at favored breakpoints. 
  Initial forerunners of 4 to 6 feet at 20 to 22 seconds will 
  arrive Tuesday morning result in an increased risk for 
  dangerous sneaker waves. Additionally, these waves will result 
  in an increased risk of strong rip currents and coastal 
  erosion.

* WHERE...San Francisco Peninsula Coast, San Francisco, Coastal 
  North Bay Including Point Reyes National Seashore, Southern 
  Monterey Bay and Big Sur Coast and Northern Monterey Bay.

* WHEN...For the Coastal Flood Advisory, until 1 PM PST this 
  afternoon. For the High Surf Advisory, from 10 AM this morning 
  to 3 PM PST Wednesday.

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. Dangerous swimming and 
  surfing conditions and localized beach erosion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$
244 
WHUS46 KMTR 130516
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
916 PM PST Tue Jan 12 2021

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST TONIGHT TO 3 PM PST WEDNESDAY...

.A large, long period northwest swell will impact the coast 
through Wednesday afternoon with breaking waves of 20 to 25 feet, 
locally up to 30 feet at favored breakpoints. Expect dangerous 
sneaker waves, strong rip currents, coastal erosion. The swell 
and associated waves will build and peak tonight.

CAZ006-505-509-529-530-131400-
/O.CON.KMTR.SU.Y.0004.000000T0000Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
916 PM PST Tue Jan 12 2021

...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 3 PM PST
WEDNESDAY...

* WHAT...For the High Surf Advisory, large breaking waves of 20 to
  25 feet, locally up to 30 feet at favored breakpoints. Expect 
  dangerous sneaker waves, strong rip currents, coastal erosion.
 
* WHERE...San Francisco Peninsula Coast, San Francisco, Coastal 
  North Bay Including Point Reyes National Seashore, Southern 
  Monterey Bay and Big Sur Coast and Northern Monterey Bay. 

* WHEN...To 3 PM PST Wednesday. 

* IMPACTS...Flooding of lots, parks, and roads with only 
  isolated road closures expected. Dangerous swimming and 
  surfing conditions and localized beach erosion. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If travel is required, allow extra time as some roads may be
closed. Do not drive around barricades or through water of
unknown depth. Take the necessary actions to protect flood-prone
property.

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$
643 
WHUS46 KMTR 131044
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
244 AM PST Wed Jan 13 2021

...LARGE, LONG PERIOD NORTHWEST SWELL WILL RESULT IN HAZARDOUS
CONDITIONS ALONG THE COAST THIS MORNING TO 3 PM PST WEDNESDAY...

.The large northwest swell continues to impact the coast through 
Wednesday afternoon with breaking waves of 20 to 25 feet, locally 
up to 30 feet at favored breakpoints. Expect dangerous strong rip 
currents, coastal erosion. 

CAZ006-505-509-529-530-132300-
/O.CON.KMTR.SU.Y.0004.000000T0000Z-210113T2300Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
244 AM PST Wed Jan 13 2021

...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 3 PM PST THIS
AFTERNOON...

* WHAT...Large breaking waves of 20 to 25 feet, locally up to 30
  feet at favored breakpoints. Expect strong rip currents and 
  coastal erosion.

* WHERE...Coastal North Bay Including Point Reyes National 
  Seashore, Southern Monterey Bay and Big Sur Coast, San 
  Francisco Peninsula Coast, San Francisco and Northern Monterey 
  Bay.

* WHEN...Until 3 PM PST this afternoon.

* IMPACTS...Large wave breaks making for dangerous swimming and 
  surfing conditions and localized beach erosion.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$
212 
WHUS46 KMTR 132203
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
203 PM PST Wed Jan 13 2021

...LARGE, LONG PERIOD NORTHWEST SWELL WILL CONTINUE TO PRODUCE 
HAZARDOUS CONDITIONS ALONG THE COAST THROUGH 9 PM PST 
THIS EVENING...

.The large northwest swell continues to impact the coast through
this evening with breaking waves of 18 to 24 feet, locally up to 
28 feet at favored breakpoints. Expect dangerous strong rip 
currents and coastal erosion.

CAZ006-505-509-529-530-140500-
/O.EXT.KMTR.SU.Y.0004.000000T0000Z-210114T0500Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
203 PM PST Wed Jan 13 2021

...HIGH SURF ADVISORY NOW IN EFFECT UNTIL 9 PM PST THIS EVENING...

* WHAT...Large breaking waves of 18 to 24 feet, locally up to 28 
  feet at favored breakpoints. Expect strong rip currents and 
  coastal erosion.

* WHERE...Coastal North Bay Including Point Reyes National 
  Seashore, Southern Monterey Bay and Big Sur Coast, San 
  Francisco Peninsula Coast, San Francisco and Northern Monterey 
  Bay.

* WHEN...Until 9 PM PST this evening.

* IMPACTS...Large wave breaks making for dangerous swimming and 
  surfing conditions and localized beach erosion.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Inexperienced swimmers should remain out of the water due to
dangerous surf conditions.

&&

$$
180 
WHUS46 KMTR 140450
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
850 PM PST Wed Jan 13 2021

CAZ006-505-509-529-530-140600-
/O.EXP.KMTR.SU.Y.0004.000000T0000Z-210114T0500Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-Northern Monterey Bay-
Southern Monterey Bay and Big Sur Coast-
850 PM PST Wed Jan 13 2021

...HIGH SURF ADVISORY WILL EXPIRE AT 9 PM PST THIS EVENING...

Coastal buoys show swell heights steadily lowering since late 
afternoon and early evening. The high surf advisory will be 
allowed to expire at 9 pm PST this evening.

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Jan 11, 2:35 PM PSTCoastal Flood AdvisoryMTRMarin, Monterey, Napa, City and County of San Francisco, San Mateo, Santa Cruz and 1 more22 hr
Jan 11, 2:56 PM PSTSmall Craft AdvisoryMTR66 hr

Nearby

High Surf Advisories in California, 2021Every high surf advisory in 2021

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.