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Marine Product Dissemination Information

Marine Weather Message in Effect for the Coastal Waters

Marine section from the Area Forecast Discussion
issued at: Aug 20, 2018 8:30 PM HST

Please note that tropical cyclone operations are in effect. So as to incorporate the latest forecast information from the Central Pacific Hurricane Center (CPHC), marine forecast updates from the Honolulu Forecast Office will come shortly after forecast updates from CPHC, namely shortly after 5 and 11 am/pm, instead of the normal 4 and 10 am/pm.

A weak surface trough W of Kauai will move W away from the area tonight as high pressure builds to the N. This will result in a gradually increasing trade wind flow through Tuesday. A Small Craft Advisory (SCA) remains in effect for the windier areas around Maui and the Big Island for these stronger winds. As Hurricane Lane moves into an area S of the islands by mid-week, the pressure gradient will likely increase further, potentially requiring an expansion of the SCA. More significantly, a Tropical Storm Watch remains in effect for the coastal waters south of the Big Island. This may need to be upgraded to a Tropical Storm Warning or Hurricane Watch/Warning as the storm gets closer. There is significant uncertainty regarding the position and intensity of Lane later in the week, so it is too early to determine what impacts Lane may eventually bring, and mariners need to continue to closely monitor forecasts.

A High Surf Advisory for E facing shores of Maui and the Big Island remains in effect. As Hurricane Lane moves into an area S of the islands later this week, S swell will likely increase, with a wide variety of wave periods and directions leading to rough and potentially damaging surf. There is still significant uncertainty and it is difficult to know the level of impacts, but there is potential for large seas/swells from Lane leading to warning-level surf along E through S facing shores of the islands. Otherwise, a small NNW swell is expected to peak on Tuesday before gradually diminishing Wednesday and Thursday.

See the latest Oahu Surf Discussion (SRDHFO) for more details on surf and swell.

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Marine Graphics

The Marine Radiofax Charts for Station KVM-70 are now available via E-mail or FTP. Click here for more details on the charts available. For information on FTPMAIL click here.

Graphic Forecasts
for Hawaiian Islands and surrounding coastal waters
Pacific Streamline Analysis
(130E-110W,30S-30N)
tif Latest 00Z 06Z 12Z 18Z  
gif Latest 00Z 06Z 12Z 18Z Loop
North Pacific Surface Analysis
(130E-110W,EQ-60N)
From the Unified Surface Analysis
gif Latest 00Z 06Z 12Z 18Z Loop
Pacific Surface Forecast
(130E-110W,30S-50N)
gif 12Z Charts 24 hr 48 hr 72 hr
gif 00Z Charts 24 hr 48 hr 72 hr
Pacific Wind Wave
Analysis and Forecasts
12Z Charts
tif Analysis 24 hr 48 hr 72 hr
gif Analysis 24 hr 48 hr 72 hr
00Z Charts
tif Analysis 24 hr 48 hr 72 hr
gif Analysis 24 hr 48 hr 72 hr
Pacific Sea Surface
Temperature Analysis

satellite-derived (updated twice weekly)
Symbols & Test Chart (gif)
Symbols & Test Chart (TIF)

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About the Marine Program

Routine forecast are issued for the Hawaiian Coastal Waters, the Offshore Waters, and High Seas. Coastal Waters are within 40 nautical miles of the main Hawaiian islands. The Offshore area extends from this 40 nautical mile mark to 240 nautical miles of the main Hawaiian islands. The High Seas forecasts are issued for an area that covers approximately 15,000,000 square miles, extends as far north as 30N, and as far south as 25S, and between 120W south of the equator and 140W north of the equator to 160E.
Marine Area of Responsibility Map for High Seas
Map of Coastal Marine Zones
Map of Offshore Marine Zones

The marine forecasts issued are based on marine observations and model data. Marine observations include buoy and ship reports. Ship reports are invaluable to the NWS, and are reported through the U.S. Voluntary Observing Ship Project. If you are a mariner, please consider joining the nearly 1,000 volunteer ships from around the world that observe the weather at their location.