Alert archive / California / High Surf Advisories in 2021
High Surf Advisory 3, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this high surf advisory at Jan 7, 2021, 12:46 AM PST for 6 counties in California. It took effect at Jan 8, 2021, 6:00 AM PST. It was in force for 24 hr.
The area
The counties it named.
The facts
- Issued
- Jan 7, 2021, 12:46 AM PST (08:46 UTC)
- In effect from
- Jan 8, 2021, 6:00 AM PST
- Expired
- Jan 9, 2021, 6:00 AM PST
- In force
- 24 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 08:48 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, 8.8 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1170 m above ground
- 0-6 km bulk shear
- 46 kt
- 0-1 km storm-relative helicity
- 1 m²/s²
- 0-3 km storm-relative helicity
- 14 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
214 WHUS46 KMTR 070846 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 1246 AM PST Thu Jan 7 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST FRIDAY MORNING THROUGH SATURDAY MORNING... .Another large long period northwest swell will arrive at the coastal waters Friday morning. Swell heights will build Friday morning with breaking waves reaching 20 to 25 feet, locally higher, expected through Saturday morning. Therefore, a High Surf Advisory will be in effect Friday morning through Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold in the low to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-071700- /O.NEW.KMTR.SU.Y.0003.210108T1400Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 1246 AM PST Thu Jan 7 2021 ...HIGH SURF ADVISORY IN EFFECT FROM 6 AM FRIDAY TO 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches Friday morning through Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...From 6 AM Friday to 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... A High Surf Advisory for large breaking waves means conditions are present to support large waves along the surf zone capable of sweeping people into the frigid and turbulent ocean water. Cold water shock may cause cardiac arrest, and it also can cause an involuntary gasp reflex causing drowning, even for a good swimmer. The surf zone will be dangerous due to strong currents and powerful breaking waves. && $$
6 follow-up statements
084 WHUS46 KMTR 072112 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 112 PM PST Thu Jan 7 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST FRIDAY MORNING THROUGH SATURDAY MORNING... .Another large long period northwest swell will arrive at the coastal waters Friday morning. Swell heights will build Friday morning with breaking waves reaching 20 to 25 feet, locally higher, expected through Saturday morning. Therefore, a High Surf Advisory will be in effect Friday morning through Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold in the low to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-080700- /O.CON.KMTR.SU.Y.0003.210108T1400Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 112 PM PST Thu Jan 7 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT FROM 6 AM FRIDAY TO 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches Friday morning through Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...From 6 AM Friday to 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... A High Surf Advisory for large breaking waves means conditions are present to support large waves along the surf zone capable of sweeping people into the frigid and turbulent ocean water. Cold water shock may cause cardiac arrest, and it also can cause an involuntary gasp reflex causing drowning, even for a good swimmer. The surf zone will be dangerous due to strong currents and powerful breaking waves. && $$
962 WHUS46 KMTR 080522 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 922 PM PST Thu Jan 7 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST EARLY FRIDAY MORNING THROUGH EARLY SATURDAY MORNING... .Another large long period northwest swell will arrive at the coastal waters Friday morning. Swell heights will build Friday morning with breaking waves reaching 20 to 25 feet, locally higher, and continue through early Saturday morning. Therefore, a High Surf Advisory will be in effect from early Friday morning through early Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold, down in the lower to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-081330- /O.CON.KMTR.SU.Y.0003.210108T1400Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 922 PM PST Thu Jan 7 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT FROM 6 AM FRIDAY TO 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches Friday morning through early Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...From 6 AM Friday to 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... A High Surf Advisory for large breaking waves means conditions are present to support large waves along the surf zone capable of sweeping people into the frigid and turbulent ocean water. Cold water shock may cause cardiac arrest, and it also can cause an involuntary gasp reflex causing drowning, even for a good swimmer. The surf zone will be dangerous due to strong currents and powerful breaking waves. && $$
181 WHUS46 KMTR 081312 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 512 AM PST Fri Jan 8 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH EARLY SATURDAY MORNING... .Another large long period northwest swell will arrive at the coastal waters this morning. Swell heights will build through the morning with breaking waves reaching 20 to 25 feet, locally higher. These large breaking waves will continue through early Saturday morning. Therefore, a High Surf Advisory is in effect through early Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold, down in the lower to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-082300- /O.CON.KMTR.SU.Y.0003.210108T1400Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 512 AM PST Fri Jan 8 2021 ...HIGH SURF ADVISORY IN EFFECT UNTIL 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches Friday morning through early Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...Until 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
646 WHUS46 KMTR 082249 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 249 PM PST Fri Jan 8 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH EARLY SATURDAY MORNING... .Another large long period northwest swell has arrived along the coast. Breaking waves are expected at 20 to 25 feet, locally higher at favored breakpoints. These large breaking waves will continue through early Saturday morning. Therefore, a High Surf Advisory is in effect through early Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold, down in the lower to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-090700- /O.CON.KMTR.SU.Y.0003.000000T0000Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 249 PM PST Fri Jan 8 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches through early Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...Until 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... A High Surf Advisory for large breaking waves means conditions are present to support large waves along the surf zone capable of sweeping people into the frigid and turbulent ocean water. Cold water shock may cause cardiac arrest, and it also can cause an involuntary gasp reflex causing drowning, even for a good swimmer. The surf zone will be dangerous due to strong currents and powerful breaking waves. && $$
061 WHUS46 KMTR 090519 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 919 PM PST Fri Jan 8 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH EARLY SATURDAY MORNING... .Large long period northwest swell will result in breaking waves from 20 to 25 feet, locally higher at favored breakpoints. These large breaking waves will continue through early Saturday morning. Therefore, a High Surf Advisory is in effect through early Saturday morning for an increased risk of rip currents and large shore break. Additionally, sea surface temperatures remain cold, down in the lower to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. CAZ006-505-509-529-530-091400- /O.CON.KMTR.SU.Y.0003.000000T0000Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 919 PM PST Fri Jan 8 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 6 AM PST SATURDAY... * WHAT...Large breaking waves of 20 to 25 feet, locally higher at favored breakpoints, are expected at west to northwest facing beaches through early Saturday morning. * WHERE...Main threat will be at west to northwest facings beaches along the entire coastline from Sonoma county southward through Big Sur in Monterey county. * WHEN...Until 6 AM PST Saturday. * IMPACTS...Large breaking waves can sweep people off jetties and rocks, and into dangerous seas. 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. * ADDITIONAL DETAILS...Another even larger long period swell will arrive Sunday, bringing additional hazards to the coast. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... A High Surf Advisory for large breaking waves means conditions are present to support large waves along the surf zone capable of sweeping people into the frigid and turbulent ocean water. Cold water shock may cause cardiac arrest, and it also can cause an involuntary gasp reflex causing drowning, even for a good swimmer. The surf zone will be dangerous due to strong currents and powerful breaking waves. && $$
803 WHUS46 KMTR 091350 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 550 AM PST Sat Jan 9 2021 CAZ006-505-509-529-530-091500- /O.EXP.KMTR.SU.Y.0003.000000T0000Z-210109T1400Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 550 AM PST Sat Jan 9 2021 ...HIGH SURF ADVISORY WILL EXPIRE AT 6 AM PST EARLY THIS MORNING... Wave heights are slowly diminishing, so the advisory has been allowed to expire. However, despite the lessening trend of wave heights, the ocean remains very active. Caution is still advised if you go to the coast on Saturday. Be sure to keep pets on leashes, stay off rocks and coastal jetties, and never turn your back to the ocean! $$
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.