In a tidal day with two highs, the taller one is the higher high water and the other the lower high water; the lows split the same way into higher low and lower low water. Datum calculations average these specific phases to give MHHW and MLLW. Where only one high occurs in a day, it is counted as the higher high.
Higher high water is at 2140 tonight, so don't leave the skiff on the beach past dinner.
Also heard as
- HHW
Related terms
MHHW
Mean Higher High Water: the average height of the higher of each day's two high waters over the datum epoch.
MLLW
Mean Lower Low Water: the average height of the lower of each day's two low waters, used as chart datum in the United States.
Diurnal inequality
How much the day's two high waters, or its two low waters, differ in height from each other.
Low-low
Shorthand for the lower low water of the day in places with mixed tides.