Buoy 51000: Northern Hawaii One

How to Read Station 51000

This is a floating buoy, so its seas are measured rather than modeled. Significant wave height is the average of the highest third of the waves, which means roughly one wave in ten is noticeably bigger than the number, and the largest in an hour can be close to twice it.

How the status is read. The station’s wind and seas are held against the lines of a typical 25 to 35 ft center console (CAUTION above 15 kt or 3 ft seas, NO-GO above 22 kt or 5 ft seas). When it reports only one of the two, the status says so: a GO from one instrument reads “GO on wind; seas not measured” and is drawn lighter, because half the picture is not a full GO, while a CAUTION or NO-GO from one reading stands and names what was not measured. A Gale, Storm, Hurricane Force Wind, Hurricane, Tropical Storm or Special Marine Warning in force on this water makes it NO-GO whatever the station reads, even when it reads nothing, and a Small Craft Advisory in force makes it at least CAUTION. Alerts below are listed in force first, then the ones still to come, by when they start.

Period matters as much as height. The period printed is the dominant one, the period of the waves carrying the most energy. On its own, four feet at ten seconds is a long swell and four feet at four seconds is a short steep chop that stops a boat. But a long period does not make a sea gentle: a distant swell can carry the headline period while the local wind raises a steep sea on top of it, which is why the wind sea and the swell are listed apart when their periods differ or the wind sea is big enough to be a sea of its own. Wind against tide steepens everything, and a buoy cannot see that from where it floats. Age matters too: stations go quiet, and a reading that has not updated in three hours is history rather than weather.

This station sits in the NWS marine zone Hawaiian Offshore Waters (PHZ180), which is the forecast we read alongside it.