Alert archive / Hawaii / High Surf Advisories in 2021
High Surf Advisory 21, NWS Honolulu, HI
NWS Honolulu, HI issued this high surf advisory at Apr 30, 2021, 3:34 PM HST for Honolulu County, Kauai County, Hawaii. It was in force for 18 hr.
The area
The counties it named.
The facts
- Issued
- Apr 30, 2021, 3:34 PM HST (01:34 UTC)
- Expired
- May 1, 2021, 9:21 AM HST
- In force
- 18 hr
- Issued by
- NWS Honolulu, HI
Counties Honolulu County, HI, Kauai County, HI
The radar
The South Kauai radar (PHKI), 76 km from the middle of the area, began a volume at 01:35 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
Lihue, (PHLI), launched 00:00Z, 1.6 hours before the alert went out and 60 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
- 8 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 918 m above ground
- 0-6 km bulk shear
- 12 kt
- 0-1 km storm-relative helicity
- 17 m²/s²
- 0-3 km storm-relative helicity
- 5 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
813 WHHW40 PHFO 010134 CFWHFO Coastal Hazard Message National Weather Service Honolulu HI 334 PM HST Fri Apr 30 2021 ...HIGH SURF ADVISORY IN EFFECT FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI AND OAHU... .A building long-period west-northwest swell building will peak early Saturday morning, resulting in advisory level surf along north and west facing shores of Niihau, Kauai, and Oahu through the day Saturday. HIZ001-003-006-007-029-011445- /O.NEW.PHFO.SU.Y.0021.210501T0134Z-210502T0400Z/ Niihau-Kauai Southwest-Waianae Coast-Oahu North Shore-Kauai North- 334 PM HST Fri Apr 30 2021 ...HIGH SURF ADVISORY IN EFFECT UNTIL 6 PM HST SATURDAY... * WHAT...Surf building to 14 to 18 feet along north facing shores of Niihau and Kauai, and to 12 to 16 feet along north facing shores of Oahu. Surfing building to 10 to 14 feet along west facing shores of Niihau and Kauai, and to 8 to 12 feet along west facing shores of Oahu. * WHERE...north and west facing shores of Kauai, Oahu, and Niihau. * WHEN...Until 6 PM HST Saturday. * IMPACTS...Moderate. Expect strong breaking waves, shore break, and strong longshore and rip currents making swimming difficult and dangerous. PRECAUTIONARY/PREPAREDNESS ACTIONS... Beachgoers, swimmers, and surfers should heed all advice given by ocean safety officials and exercise caution. Boaters should expect recreational surfers and body boarders utilizing harbor channels to access surfing areas. && $$
2 follow-up statements
932 WHHW40 PHFO 011343 CFWHFO Coastal Hazard Message National Weather Service Honolulu HI 343 AM HST Sat May 1 2021 ...HIGH SURF ADVISORY IN EFFECT FOR NORTH AND WEST FACING SHORES OF NIIHAU KAUAI AND OAHU... .A late season west-northwest swell will peak early this morning, resulting in advisory-level surf along north and west facing shores of Niihau, Kauai, and Oahu today. Surf will gradually lower tonight through Monday as the swell eases. HIZ001-003-006-007-029-020245- /O.CON.PHFO.SU.Y.0021.000000T0000Z-210502T0400Z/ Niihau-Kauai Southwest-Waianae Coast-Oahu North Shore-Kauai North- 343 AM HST Sat May 1 2021 ...HIGH SURF ADVISORY REMAINS IN EFFECT UNTIL 6 PM HST THIS EVENING... * WHAT...Surf of 12 to 16 feet along north facing shores of Niihau, Kauai, and Oahu. Surf of 10 to 14 feet along west facing shores of Niihau and Kauai, and 8 to 12 feet along west facing shores of Oahu. * WHERE...North and west facing shores of Niihau, Kauai, and Oahu. * WHEN...Until 6 PM HST this evening. * IMPACTS...Moderate. Expect strong breaking waves, shore break, and strong longshore and rip currents making swimming difficult and dangerous. PRECAUTIONARY/PREPAREDNESS ACTIONS... Beachgoers, swimmers, and surfers should heed all advice given by ocean safety officials and exercise caution. && $$ Gibbs
133 WHHW40 PHFO 011921 CFWHFO Coastal Hazard Message National Weather Service Honolulu HI 921 AM HST Sat May 1 2021 HIZ001-003-006-007-029-012030- /O.CAN.PHFO.SU.Y.0021.000000T0000Z-210502T0400Z/ Niihau-Kauai Southwest-Waianae Coast-Oahu North Shore-Kauai North- 921 AM HST Sat May 1 2021 ...HIGH SURF ADVISORY IS CANCELLED... $$
Nearby
High Surf Advisories in Hawaii, 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.