Alert archive / California / Beach Hazards Statements in 2023

Beach Hazards Statement 13, NWS San Francisco Bay Area, CA

October 14, 20236 counties in California

NWS San Francisco Bay Area, CA issued this beach hazards statement at Oct 14, 2023, 11:13 PM PDT for 6 counties in California. It took effect at Oct 15, 2023, 5:00 AM PDT. It was in force for 21 hr.

The area

The counties it named.

The facts

Issued
Oct 14, 2023, 11:13 PM PDT (06:13 UTC)
In effect from
Oct 15, 2023, 5:00 AM PDT
Expired
Oct 16, 2023, 1:41 AM PDT
In force
21 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 06:16 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 00:00Z, 6.2 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 00:00Z on 2023-10-15Temperature 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 00:00Z on 2023-10-15The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 28 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
822 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
28 m²/s²
0-3 km storm-relative helicity
77 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

060 
WHUS46 KMTR 150613
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
1113 PM PDT Sat Oct 14 2023

CAZ006-505-509-530-151415-
/O.NEW.KMTR.BH.S.0013.231015T1200Z-231016T1200Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
1113 PM PDT Sat Oct 14 2023

...BEACH HAZARDS STATEMENT IN EFFECT FROM 5 AM PDT SUNDAY THROUGH
LATE SUNDAY NIGHT...

* WHAT...Increased threat of sneaker waves expected.

* WHERE...West and northwest facing beaches including San 
  Francisco, Coastal North Bay Including Point Reyes National 
  Seashore, San Francisco Peninsula Coast and Southern Monterey 
  Bay and Big Sur Coast Counties.

* WHEN...From 5 AM PDT Sunday through late Sunday night.

* IMPACTS...Large, unexpected waves can sweep across the beach
  without warning, sweeping people into the sea from rocks,
  jetties, and beaches. These sneaker waves can also move large
  objects such as logs, crushing anyone caught underneath. Maximum
  surf height can reach 15 ft.


PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain out of the water to avoid hazardous swimming conditions.
Don't be fooled by an ocean that looks calm. There can be 30 
minutes of small waves before a sneaker wave strikes. Avoid rocks 
and jetties. Avoid steep beaches. Stay much farther back from the 
water and never turn your back on the ocean.

&&

$$
4 follow-up statements
731 
WHUS46 KMTR 150652
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
1152 PM PDT Sat Oct 14 2023

CAZ006-505-509-530-151500-
/O.CON.KMTR.BH.S.0013.231015T1200Z-231016T1200Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
1152 PM PDT Sat Oct 14 2023

...BEACH HAZARDS STATEMENT REMAINS IN EFFECT FROM 5 AM PDT SUNDAY
THROUGH LATE SUNDAY NIGHT...

* WHAT...Increased threat of sneaker waves expected.

* WHERE...West and northwest facing beaches including San 
  Francisco, Coastal North Bay Including Point Reyes National 
  Seashore, San Francisco Peninsula Coast and Southern Monterey 
  Bay and Big Sur Coast Counties.

* WHEN...From 5 AM PDT Sunday through late Sunday night.

* IMPACTS...Large, unexpected waves can sweep across the beach
  without warning, sweeping people into the sea from rocks,
  jetties, and beaches. These sneaker waves can also move large
  objects such as logs, crushing anyone caught underneath.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain out of the water to avoid hazardous swimming conditions.

&&

$$
050 
WHUS46 KMTR 151209
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
509 AM PDT Sun Oct 15 2023

CAZ006-505-509-530-160330-
/O.CON.KMTR.BH.S.0013.000000T0000Z-231016T1200Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
509 AM PDT Sun Oct 15 2023

...BEACH HAZARDS STATEMENT REMAINS IN EFFECT THROUGH LATE
TONIGHT...

* WHAT...Increased threat of sneaker waves expected due to long
  period northwest swell.

* WHERE...West and northwest facing beaches of coastal North Bay,
  San Francisco Peninsula Coast, San Mateo county coast, Southern
  Monterey Bay, and Big Sur coast.

* WHEN...Through late tonight.

* IMPACTS...Large, unexpected waves can sweep across the beach
  without warning, sweeping people into the sea from rocks,
  jetties, and beaches. These sneaker waves can also move large
  objects such as logs, crushing anyone caught underneath.
.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain out of the water to avoid hazardous swimming conditions.
Don't be fooled by an ocean that looks calm. There can be 30 
minutes of small waves before a sneaker wave strikes. Avoid rocks 
and jetties. Avoid steep beaches. Stay much farther back from the 
water and never turn your back on the ocean.

&&

$$
505 
WHUS46 KMTR 160322
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
822 PM PDT Sun Oct 15 2023

CAZ006-505-509-530-161200-
/O.CON.KMTR.BH.S.0013.000000T0000Z-231016T1200Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
822 PM PDT Sun Oct 15 2023

...BEACH HAZARDS STATEMENT REMAINS IN EFFECT UNTIL 5 AM PDT
MONDAY...

* WHAT...Increased threat of sneaker waves expected due to long 
  period northwest swell.

* WHERE...West and northwest facing beaches of coastal North 
  Bay, San Francisco Peninsula Coast, San Mateo county coast, 
  Southern Monterey Bay, and Big Sur coast.

* WHEN...Until 5 AM PDT Monday.

* IMPACTS...Large, unexpected waves can sweep across the beach 
  without warning, sweeping people into the sea from rocks, 
  jetties, and beaches. These sneaker waves can also move large 
  objects such as logs, crushing anyone caught underneath. .



PRECAUTIONARY/PREPAREDNESS ACTIONS...

Remain out of the water to avoid hazardous swimming conditions.
Don't be fooled by an ocean that looks calm. There can be
30 minutes of small waves before a sneaker wave strikes. Avoid
rocks and jetties. Avoid steep beaches. Stay much farther back
from the water and never turn your back on the ocean.

&&

$$
709 
WHUS46 KMTR 160841
CFWMTR

Coastal Hazard Message
National Weather Service San Francisco CA
141 AM PDT Mon Oct 16 2023

CAZ006-505-509-530-160945-
/O.CAN.KMTR.BH.S.0013.000000T0000Z-231016T1200Z/
San Francisco-
Coastal North Bay Including Point Reyes National Seashore-
San Francisco Peninsula Coast-
Southern Monterey Bay and Big Sur Coast-
141 AM PDT Mon Oct 16 2023

...BEACH HAZARDS STATEMENT IS CANCELLED...

Period of northwest swell has diminished to 16-17 seconds, so 
there is no longer an enhanced sneaker wave risk. 

$$

The office that day

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

IssuedProductOfficeCountiesLasted
Oct 15, 1:13 AM PDTDense Fog AdvisoryMTRMarin, Monterey, Napa, San Benito, City and County of San Francisco, San Mateo and 2 more9 hr
Oct 15, 1:22 AM PDTMarine Dense Fog AdvisoryMTR10 hr
Oct 15, 2:24 AM PDTSmall Craft AdvisoryMTR43 hr

Nearby

Beach Hazards Statements in California, 2023Every beach hazards statement in 2023

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.