Alert archive / California / High Surf Advisories in 2021
High Surf Advisory 2, NWS San Francisco Bay Area, CA
NWS San Francisco Bay Area, CA issued this high surf advisory at Jan 3, 2021, 8:38 AM PST for 6 counties in California. It took effect at Jan 3, 2021, 7:00 PM PST. It was in force for 52 hr.
The area
The counties it named.
The facts
- Issued
- Jan 3, 2021, 8:38 AM PST (16:38 UTC)
- In effect from
- Jan 3, 2021, 7:00 PM PST
- Expired
- Jan 5, 2021, 11:00 PM PST
- In force
- 52 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 16:36 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, 4.6 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.
- Mixed-layer CAPE
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 599 m above ground
- 0-6 km bulk shear
- 60 kt
- 0-1 km storm-relative helicity
- 42 m²/s²
- 0-3 km storm-relative helicity
- 50 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
882 WHUS46 KMTR 031638 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 838 AM PST Sun Jan 3 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST SUNDAY NIGHT THROUGH TUESDAY NIGHT... .The initial High Surf Advisory will be allowed to expire this morning as wave heights and periods subside. However, strong storms in the Pacific continue to generate large long period northwest swell for the Bay Area and Central Coast with the next swell set to arrive this evening. The primary hazard this evening and overnight will be infrequent yet dangerous sneaker waves and strong rip currents as the initial forerunners come in at periods of 20 to 22 seconds. Swell heights will build Monday morning with breaking waves 18 to 24 feet, locally higher, expected through late Monday afternoon. Waves will continue to build overnight Monday peaking through Tuesday with breaking waves of 25 to nearly 30 feet, locally higher at favored breakpoints. Therefore, a High Surf Advisory will be in effect from this evening until Tuesday night for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-040300- /O.EXP.KMTR.SU.Y.0001.000000T0000Z-210103T1700Z/ /O.NEW.KMTR.SU.Y.0002.210104T0300Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 838 AM PST Sun Jan 3 2021 ...HIGH SURF ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO 11 PM PST TUESDAY... ...HIGH SURF ADVISORY WILL EXPIRE AT 9 AM PST THIS MORNING... * WHAT...Infrequent yet dangerous sneaker waves and strong rip currents are expected this evening and tonight. Large and dangerous breaking waves of 18 to 24 feet are expected at west to northwest facing beaches Monday morning through Monday afternoon. Waves will continue to build overnight Monday through Tuesday with breaking waves of 25 to nearly 30 feet possible, locally higher at favored breakpoints * 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 7 PM this evening to 11 PM PST Tuesday. * IMPACTS...Sneaker waves and 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...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Conditions are present to support a heightened risk of unsuspecting beach goers being swept into the sea by a wave due to an increased threat of sneaker waves. People walking along the beach should never turn their back to the sea. Fisherman should avoid fishing from rocks or jetties. 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. && $$
7 follow-up statements
097 WHUS46 KMTR 040253 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 653 PM PST Sun Jan 3 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST SUNDAY NIGHT THROUGH TUESDAY NIGHT... .Another large long period northwest swell is set to arrive at the Bay Area and Central Coast this evening. The primary hazard this evening and overnight will be infrequent yet dangerous sneaker waves and strong rip currents as the initial forerunners come in at periods of 20 to 22 seconds. Swell heights will build Monday morning with breaking waves 18 to 24 feet, locally higher, expected through late Monday afternoon. Waves will continue to build overnight Monday peaking through Tuesday with breaking waves of 25 to nearly 30 feet, locally higher at favored breakpoints. Therefore, a High Surf Advisory will be in effect from this evening until Tuesday night for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-041100- /O.CON.KMTR.SU.Y.0002.210104T0300Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 653 PM PST Sun Jan 3 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST TUESDAY... * WHAT...Infrequent yet dangerous sneaker waves and strong rip currents are expected this evening and tonight. Large and dangerous breaking waves of 18 to 24 feet are expected at west to northwest facing beaches Monday morning through Monday afternoon. Waves will continue to build overnight Monday through Tuesday with breaking waves of 25 to nearly 30 feet possible, locally higher at favored breakpoints * 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 7 PM this evening to 11 PM PST Tuesday. * IMPACTS...Sneaker waves and 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...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Conditions are present to support a heightened risk of unsuspecting beach goers being swept into the sea by a wave due to an increased threat of sneaker waves. People walking along the beach should never turn their back to the sea. Fisherman should avoid fishing from rocks or jetties. 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. && $$
815 WHUS46 KMTR 041059 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 259 AM PST Mon Jan 4 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH TUESDAY NIGHT... .Another large long period northwest swell has arrived at the coastal waters. Swell heights will build this morning with breaking waves 18 to 24 feet, locally higher, expected through late this afternoon. Waves will continue to build overnight Monday peaking through Tuesday with breaking waves of 25 to nearly 30 feet, locally higher at favored breakpoints. Therefore, a High Surf Advisory will be in effect through Tuesday night for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-042300- /O.CON.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 259 AM PST Mon Jan 4 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST TUESDAY... * WHAT...Large breaking waves of 18 to 24 feet are expected at west to northwest facing beaches Monday morning through Monday afternoon. Waves will continue to build overnight Monday through Tuesday with breaking waves of 25 to nearly 30 feet possible, locally higher at favored breakpoints . * 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 Counties. * WHEN...Until 11 PM PST Tuesday. * IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
837 WHUS46 KMTR 042046 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 1246 PM PST Mon Jan 4 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH TUESDAY NIGHT... .A large long period northwest swell has arrived and breakers of 18 to 24 feet are possible through Monday. Swell heights will continue to build later tonight before peaking on Tuesday with breaking waves of 25 to nearly 30 feet, locally higher at favored breakpoints. Therefore, a High Surf Advisory will be in effect through Tuesday night for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-050700- /O.CON.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ 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 PM PST Mon Jan 4 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST TUESDAY... * WHAT...Large breaking waves of 18 to 24 feet are expected at west to northwest facing beaches on Monday. Waves will continue to build overnight Monday through Tuesday with breaking waves of 25 to nearly 30 feet possible, locally higher at favored breakpoints. * 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 Counties. * WHEN...Until 11 PM PST Tuesday. * IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
932 WHUS46 KMTR 050432 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 832 PM PST Mon Jan 4 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH TUESDAY NIGHT... .The large northwest swell continues to build overnight and breaking waves of 18 to 24 feet are possible peaking on Tuesday with breaking waves of 25 to nearly 30 feet, locally higher at favored breakpoints. A High Surf Advisory is in effect through Tuesday night for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-051100- /O.CON.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 832 PM PST Mon Jan 4 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST TUESDAY... * WHAT...Large breaking waves of 18 to 24 feet are expected at west to northwest facing beaches on Monday. Waves will continue to build overnight Monday through Tuesday with breaking waves of 25 to nearly 30 feet possible, locally higher at favored breakpoints. * 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 Counties. * WHEN...Until 11 PM PST Tuesday. * IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
024 WHUS46 KMTR 051059 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 259 AM PST Tue Jan 5 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH THIS EVENING... .The large northwest swell continues to build overnight and breaking waves of 18 to 24 feet are expected, with 25 to nearly 30 feet possible at favored breakpoints. A High Surf Advisory is in effect through tonight for an increased risk of dangerous sneaker waves and large shore break. Additionally, sea surface temperatures remain cold in the low to mid 50s. Cold water drownings occur each year with these events but are avoidable by remaining a safe distance from the coastline. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-051900- /O.CON.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 259 AM PST Tue Jan 5 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST THIS EVENING... * WHAT...Large breaking waves of 18 to 24 feet are expected at west to northwest facing beaches, with 25 to nearly 30 feet possible at favored breakpoints. * WHERE...Coastal North Bay Including Point Reyes National Seashore, Southern Monterey Bay and Big Sur Coast, San Francisco Peninsula Coast, San Francisco and Northern Monterey Bay Counties. * WHEN...Until 11 PM PST this evening. * IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
576 WHUS46 KMTR 051900 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 1100 AM PST Tue Jan 5 2021 ...LARGE LONG PERIOD NORTHWEST SWELL WILL BRING HAZARDOUS CONDITIONS ALONG THE COAST THROUGH THIS EVENING... .A large long period northwest swell will continue into tonight resulting in breakers of 18 to 24 feet. Breakers of 25 to 30 feet are possible at favored breakpoints. The High Surf Advisory will remain in effect until 11 pm tonight for an increased risk of dangerous sneaker waves 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. Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. CAZ006-505-509-529-530-060700- /O.CON.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 1100 AM PST Tue Jan 5 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 11 PM PST THIS EVENING... * WHAT...Large breaking waves of 18 to 24 feet are expected at west to northwest facing beaches, with 25 to nearly 30 feet possible at favored breakpoints. * 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 Counties. * WHEN...Until 11 PM PST this evening. * IMPACTS...Dangerous swimming and surfing conditions and localized beach erosion. * ADDITIONAL DETAILS...Periods of subsiding and building northwest swell will continue throughout much of the week. Continued vigilance is advised. PRECAUTIONARY/PREPAREDNESS ACTIONS... Inexperienced swimmers should remain out of the water due to dangerous surf conditions. && $$
321 WHUS46 KMTR 060703 CFWMTR Coastal Hazard Message National Weather Service San Francisco CA 1103 PM PST Tue Jan 5 2021 CAZ006-505-509-529-530-060815- /O.EXP.KMTR.SU.Y.0002.000000T0000Z-210106T0700Z/ San Francisco- Coastal North Bay Including Point Reyes National Seashore- San Francisco Peninsula Coast-Northern Monterey Bay- Southern Monterey Bay and Big Sur Coast- 1103 PM PST Tue Jan 5 2021 ...HIGH SURF ADVISORY HAS EXPIRED... Seas will continue to slowly subside overnight into early Wednesday morning. Another large swell train is likely by Friday with another high surf event possible. $$
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.